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SPECIAL EXHIBIT |
1 From the Department of Radiology, University of Michigan Health System, 1500 E Medical Center Dr, Ann Arbor, MI 48109-0030. Received October 18, 1999; accepted October 20. Address reprint requests to the author.
Index Terms: Brain neoplasms, in infants and children, 131.315 • Bronchi, abnormalities, 61.139 • Esophagus, diseases, 71.699 • Granuloma, 671.3183 • Hematopoiesis, extramedullary, 32.659 • Kidney neoplasms, 811.319 • Neoplasms, in infants and children, 131.315 • Nervous system, neoplasms, 461.325 • Neurofibromatosis, 4.1831 • Pancreas, neoplasms, 770.3125 • Parathyroid, hyperparathyroidism, 452.5323 • Retroperitoneal space, neoplasms, 819.327 • Tendons, injuries, 452.4857 • Trachea, neoplasms, 671.3183
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Case 1 |
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Discussion
Mucin-producing tumors of the pancreas originate from the epithelium lining of the pancreatic duct. They may arise from the peripheral ducts or from the main pancreatic duct and its branches. Those that arise from the peripheral ducts are called mucinous cystadenomas and cystadenocarcinomas, whereas those that arise from the main duct are referred to as intraductal mucin-producing tumors. Intraductal mucin-producing tumors have also been called "ductectatic" mucinous, mucus-producing, mucin-producing, or mucin-hypersecreting neoplasms of the pancreas. At histologic examination, the lesion may demonstrate simple hyperplasia, low- or high-grade dysplasia, or foci of malignant tumor transformation (Fig 4).
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Imaging features reflect the hypersecretion of mucus. On sonograms, mucin is echogenic and may be indistinguishable from pancreatic parenchyma. Thus, the dilatation of the pancreatic duct may not be apparent. However, if a more localized collection of mucin is causing obstruction, the ductal dilatation proximal to the mucin may be identified.
Similar features are found on CT scans. Mucin has a higher attenuation value than that of duct fluid such that it may be difficult to recognize a dilated, mucin-filled pancreatic duct. Calcific deposits may be seen within the mucinous collections and lead to an incorrect diagnosis of chronic pancreatitis. The most useful finding on CT scans is dilatation of the pancreatic duct proximal to obstruction by mucin or cystic ectasia of the branch ducts.
Endoscopic retrograde cholangiopancreatography (ERCP) has the advantage of combining endoscopic visualization of the duodenum and duct orifice with radiographic opacification of the pancreatic duct. The papilla may be seen protruding into the duodenal lumen, and it may be possible to visualize the mucin leaking into the duodenum from a dilated papillary orifice. Opacification of the duct demonstrates dilatation and filling defects due to mucin. In most patients, the ERCP findings are diagnostic.
Magnetic resonance (MR) cholangiopancreatography may also be used. The sensitivity of detecting dilatation of the main pancreatic duct is equivalent with MR cholangiopancreatography and ERCP. Although detection of normal ductal branches is superior with ERCP, MR cholangiopancreatography is more sensitive in the detection of cystic dilatation of the branches because the mucin produced by the lesion prevents good opacification by the contrast material.
The clinical presentation and even the imaging findings at CT and US may not enable the distinction of an intraductal mucin-producing tumor from chronic pancreatitis. The features at ERCP are usually diagnostic, and early reports on use of MR cholangiopancreatography suggest that it may be as accurate as ERCP. Treatment is surgical resection.
Suggested Readings
Itai Y. Different terms for the same disease: intraductal mucin-producing tumor versus mucinous tumor of the pancreas (letter). Radiology 1996; 200:285.
Koito K, Namieno T, Ichimura T, et al. Mucin-producing pancreatic tumors: comparison of MR cholangiopancreatography with endoscopic retrograde cholangiopancreatography. Radiology 1998; 208:231–237.
Onaya H, Itai Y, Niitsu M, et al. Ductectatic mucinous cystic neoplasms of the pancreas: evaluation with MR cholangiopancreatography. AJR Am J Roentgenol 1998; 171:171–177.
Procacci C, Graziani R, Bicego E, et al. Intraductal mucin-producing tumors of the pancreas: imaging findings. Radiology 1996; 198:249–257.
Procacci C, Megibow AJ, Carbognin G, et al. Intraductal papillary mucinous tumor of the pancreas: a pictorial essay. RadioGraphics 1999; 19:1447–1463.
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Case 2 |
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Discussion
Juxtaglomerular tumors are renin-producing tumors of the juxtaglomerular apparatus of the kidney. Although rare, they must be considered in the differential diagnosis, especially in patients with accelerated or poorly controlled hypertension, because they represent a surgically correctable form of hypertension.
First described by Robertson et al (1967), juxtaglomerular tumors have been found in patients ranging from 7 to 58 years of age. The mean age at detection is 24 years. These tumors are almost twice as common in women than in men. The clinical presentation includes marked and sustained hypertension. At physical examination, hypertensive retinopathy is a common finding. Laboratory testing may reveal evidence of secondary aldosteronism with hypokalemia and elevated levels of aldosterone. The presence of high renin values confirms that the patients have secondary aldosteronism rather than primary aldosteronism (Conn syndrome).
The term juxtaglomerular tumor should be used only for tumors that arise from the afferent arterioles of the glomeruli. They are benign neoplasms, and neither malignant transformation nor local recurrence after surgery has been reported. The tumors range in size from 0.8 to 6.5 cm in diameter.
The radiologic evaluation of these patients often includes renal arteriography and renal vein sampling to measure renin levels to look for a possible renovascular cause of renin-mediated hypertension. In prior years, excretory urography was performed, often as a "hypertensive urogram," to detect a delay in contrast material excretion as a sign of renal artery stenosis. However, in these patients, there is no renal artery lesion, excretion of contrast material is prompt bilaterally, and the juxtaglomerular tumors are often too small to be detected at urography.
To look for causes of renal artery stenosis, renal arteriography is performed by placing a pigtail catheter in the abdominal aorta just below the level of the renal arteries. Injection of contrast material with a mechanical pump injector creates a jet of contrast agent sufficient to completely opacify the aorta at the level of the renal arteries but only minimally opacify the superior mesenteric and celiac arteries. Images may be obtained in anteroposterior and both oblique projections to optimally image the origins of the renal arteries, which often have an oblique rather than lateral origin from the aorta. At arteriography, juxtaglomerular tumors are usually small and hypovascular. In the most recent series reported, arteriographic findings were positive in only 43% of cases (Haab et al, 1995). These tumors are easily overlooked if the parenchyma of the kidney is not carefully examined. Selective renal artery injections are recommended to detect a renal tumor (Fig 6).
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CT is the most sensitive method of detecting a juxtaglomerular tumor. Because the attenuation of the tumor is similar to that of normal renal parenchyma, contrast-enhanced images are often needed to detect the mass, which enhances less than the renal cortex.
MR imaging may be performed either to examine the renal arteries or to detect a renal mass. MR imaging provides excellent delineation of the renal arteries, although the spatial resolution may not be sufficient to confidently exclude involvement by fibromuscular dysplasia. Images obtained early after intravenous administration of contrast material may demonstrate delayed opacification of the parenchyma of one kidney if there is a significant renal artery stenosis. A juxtaglomerular tumor has been reported to have peripheral enhancement on T1-weighted images following intravenous administration of gadopentetate dimeglumine. Delayed images demonstrated reversal of the enhancement pattern, with washout of contrast material at the periphery and filling in of the central portion of the tumor.
The treatment of juxtaglomerular tumors is surgical excision. Depending on the size and location of the tumor, a nephrectomy, partial nephrectomy, or tumor resection may be performed. All seven patients reported by Haab et al (1995) underwent tumor resection without complication. Immediate cure of the hypertension and hypokalemia was achieved within 1 week after the operation.
Suggested Readings
Agrawal R, Zafar S, Jafri H, et al. Juxtaglomerular cell tumor: MR findings. J Comput Assist Tomogr 1995; 19:140–142.
Dunnick NR, Hartman DS, Ford KK, Davis CJ, Amis ES. The radiology of juxtaglomerular tumors. Radiology 1983; 147:321–326.
Haab F, Duclos JM, Guyenne T, Plouin PF, Corvol P. Renin secreting tumors: diagnosis, conservative surgical approach, and long-term results. J Urol 1995; 153:1781–1784.
Robertson PW, Klidjian A, Harding LK, et al. Hypertension due to a renin-secreting tumour. Am J Med 1967; 43:963–976.
Schonfeld AD, Jackson JA, Somerville SP, Johnson CF, Anderson PW. Renin-secreting juxtaglomerular tumor causing severe hypertension: diagnosis by computerized tomography–directed needle biopsy. J Urol 1991; 146:1607–1609.
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Case 3 |
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Diagnosis: Bilateral quadriceps tendon rupture and multiple brown tumors in a patient with secondary hyperparathyroidism.
Discussion
Rupture of a quadriceps tendon most commonly results from trauma. The diagnosis of quadriceps tendon rupture is clinical. The patient often describes acute pain and a tearing sensation in association with trauma or violent contraction of the quadriceps muscle. Physical examination reveals swelling of the knee, a palpable sulcus above the patella, and an inability to fully extend the knee despite unhampered flexion.
Spontaneous rupture may be more difficult to diagnose because there is no history of trauma and a hematoma may mask the defect in the tendon at physical examination. Bilateral rupture is even more difficult to detect, since appearances at the physical examination may be symmetric.
Plain radiography is useful for demonstrating indirect signs of tendon rupture, such as poorly defined suprapatellar swelling and forward tilting of the patella. Small fragments of avulsed bone may be seen in the suprapatellar region. The patella is often, but not always, low lying. Although US may demonstrate the break in the tendon, the rupture may be obscured by hemorrhage.
MR imaging is the most accurate method of assessing the tendons. The tendon separation and proximal retraction are clearly defined. In some patients, there is only partial tear of the quadriceps tendon. This distinction is critical because patients with only partial tear may not require surgery.
Patients with spontaneous rupture of the quadriceps tendon usually are elderly or have a chronic illness such as gout, a collagen vascular disease, diabetes mellitus, hyperparathyroidism, or chronic renal failure. In patients with systemic lupus erythematosus, there is fibrinoid degeneration of the tendon sheaths associated with round cell infiltration. In hyperparathyroidism, the effect of parathyroid hormone on the highly polymerized glycoprotein matrix may weaken the tendon.
The patient in this case suffered from chronic renal disease and showed evidence of renal osteodystrophy and secondary hyperparathyroidism. The lytic lesions proved to be brown tumors, although the differential diagnosis included amyloid deposition as well as the unlikely possibility of metastatic disease or multiple myeloma. In the past, brown tumors were considered to occur much less commonly with secondary hyperparathyroidism than with primary hyperparathyroidism. However, with earlier laboratory diagnosis of primary hyperparathyroidism, these patients manifest less severe radiographic bone changes. Thus, among patients with brown tumors, more cases are now attributed to secondary rather than primary hyperparathyroidism.
In patients undergoing chronic hemodialysis, amyloid deposition may occur in the soft tissues, including the tendons, and may contribute to tendon tears. In some cases, focal intraosseous amyloid deposition causes lytic lesions similar to those seen here. In the present case, amyloidosis was a likely diagnosis but was excluded because of the results of the bone biopsy.
Suggested Readings
Calvo E, Ferrer A, Robledo AG, et al. Bilateral simultaneous spontaneous quadriceps tendons rupture: a case report studied by magnetic resonance imaging. Clin Imaging 1997; 21:73–76.
Cruickshank B. Lesions of joints and tendon sheaths in systemic lupus erythematosus. Ann Rheum Dis 1959; 18:111–119.
Lavalle C, Aparicio LA, Moreno J, et al. Bilateral avulsion of quadriceps tendons in primary hyperparathyroidism. J Rheum 1985; 12:596–598.
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Case 4 |
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Discussion
The respiratory system begins at about the 26th day of embryologic development as the laryngotracheal groove of the primitive pharyngeal floor. The endodermal lining of the laryngotracheal tube gives rise to the epithelium of the trachea, whereas the cartilage, connective tissue, and muscle develop from the surrounding splanchnic mesenchyme. A lung bud develops from the caudal end of the laryngotracheal tube and divides into two bronchopulmonary buds.
The left pulmonary bud is slightly smaller than the right one and is directed more laterally such that an aspirated foreign body is more likely to enter the right main bronchus. The right pulmonary bud gives rise to two secondary buds, whereas only one arises from the left. Thus, there are three right pulmonary lobes (upper, middle, and lower) but only two left pulmonary lobes (upper and lower). Anomalies of bronchial division are common, although most are encountered as incidental findings in asymptomatic adults. They may be isolated anomalies or associated with a variety of other congenital disorders.
A tracheal bronchus is one that arises from the trachea proximal to the carina. Although anatomically incorrect, the term tracheal bronchus has also been used to describe an anomalous bronchus arising from the right or left main bronchus. Most such bronchi arise from the right side, either from the lower trachea within 2 cm of the carina or from the right main bronchus proximal to the origin of the right upper lobe bronchus. A tracheal bronchus can be of variable length and may aerate a portion or all of the right upper lobe or may be a blind-ending pouch. A left-sided tracheal bronchus is less common and is often only an early origin of the apicoposterior left upper lobe bronchus.
An accessory cardiac bronchus is a true supernumerary anomalous bronchus that may ventilate an accessory lobe. It arises from the medial wall of the bronchus intermedius prior to the origin of the apical segmental bronchus of the right lower lobe and usually before the origin of the middle lobe bronchus. The accessory cardiac bronchus has a round orifice and is directed caudally, toward the pericardium. It may be a short, blind-ending structure or may be a longer, branching bronchus. It is lined by normal bronchial mucosa and has cartilage within its walls, which distinguishes it from an acquired fistula or diverticulum.
In a review of the literature, Ghaye et al (1999) found 89 cases classified as an accessory cardiac bronchus. Only one similar anomaly was reported on the left side. There was a male predominance with a gender ratio of 2.8. The accessory cardiac bronchus is unrelated to the paracardiac bronchus, which is a normal bronchus arising from the medial aspect of the lower lobe in 5% of patients.
Most patients with an accessory cardiac bronchus are asymptomatic. The diagnosis is made during bronchoscopy or from imaging studies obtained for unrelated reasons. Symptomatic patients may present with recurrent infections or hemoptysis. When a patient presents with a complaint of coughing up blood, the first problem is to distinguish hemoptysis from hematemesis. Blood arising from the airway is usually mixed with frothy sputum, is bright red, and has an alkaline pH. In contrast, blood that comes from the stomach often contains food particles, is dark in color, and has an acid pH. When hemoptysis occurs in young adults, mitral stenosis, pneumonia, or bronchiectasis are likely causes. In older patients, lung cancer and tuberculosis are more common causes.
The evaluation of patients with suspected hemoptysis should consist of a clinical history, physical examination, and chest radiography. If the cause of bleeding remains unclear, bronchoscopy is indicated. However, the source of the hemoptysis will still remain unclear in 5%–10% of patients. CT of the chest can be used as an adjunct to bronchoscopy in patients thought likely to have lung cancer or as an alternative to bronchoscopy when the likelihood is low. Reformatted images may be helpful for defining anatomy (Fig 10) or as a guide to subsequent bronchoscopy. Marshall et al (1996) recommended that CT be used as the next investigation in patients with hemoptysis and normal chest radiographic findings. They stated that bronchoscopy is indicated if CT findings are equivocal or reveal evidence of tumor. Bronchoscopy is also indicated if chest CT fails to reveal the source of bleeding and hemoptysis continues for 6 months.
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Fishman AP. Pulmonary diseases and disorders. 2nd ed. New York, NY: McGraw-Hill, 1988.
Ghaye B, Kos X, Dondelinger RF. Accessory cardiac bronchus: 3D CT demonstration in nine cases. Eur Radiol 1999; 9:45–48.
Marshall TJ, Flower CDR, Jackson JE. The role of radiology in the investigation and management of patients with haemoptysis. Clin Radiol 1996; 51:391–400.
McGuinness G, Naidich DP, Garay SM, et al. Accessory cardiac bronchus: CT features and clinical significance. Radiology 1993; 189:563–566.
Moore KL. The developing human. Philadelphia, Pa: Saunders, 1973.
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Case 5 |
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Discussion
The thalassemias are a diverse group of congenital disorders containing a defect in hemoglobin synthesis. Because the defect is quantitative rather than qualitative, it produces normal hemoglobin but in reduced amounts. The red blood cells are microcytic and hypochromic. Beta thalassemia major, or Cooley anemia, is the most severe form of the congenital hemolytic anemias. Hemolysis of red blood cells leads to splenomegaly, and frequent blood transfusions result in iron overload and hemosiderosis. Skeletal abnormalities are common due to expansion of the erythroid bone marrow. Osteoporosis, coarse trabeculation of the bone, and cortical thinning are common and may lead to spontaneous fractures.
Extramedullary hematopoiesis is a compensatory phenomenon that is commonly seen in the abdomen, chest, or epidural space. It occurs with a variety of chronic anemias and myeloproliferative disorders, such as sickle cell anemia, polycythemia vera, chronic myelogenous leukemia, and thalassemia. Patients with hemoglobinopathies are more likely to have extramedullary hematopoiesis in paraosseous locations, whereas patients with myeloproliferative disorders have extraosseous masses. The liver, spleen, and lymph nodes are frequently involved as extraosseous locations because these are hematopoietic organs during embryonic life.
Involvement of the epidural space by extramedullary hematopoiesis is most common in patients with thalassemia. It may occur by direct extension from the bone marrow, stimulation of embryonic multipotential hematopoietic stem cells, or via hematogenous emboli. Patients may present with complaints of back pain or spinal cord symptoms. Extramedullary hematopoiesis usually forms a soft, red mass resembling a hematoma on its cut surface. At histologic analysis, all hematopoietic elements are found in extramedullary hematopoiesis.
Bone abnormalities are evident on plain radiographs. Expansion of the bone marrow is seen as osteoporosis with coarsened trabeculation. With severe involvement, there is expansion of the bony cortex. Spinal cord involvement may be suggested by the presence of paraosseous masses seen on chest radiographs. Along with the bone abnormalities, CT demonstrates extramedullary hematopoiesis as a soft-tissue mass that is often adjacent to involved bone. Extramedullary hematopoiesis can be distinguished from the epidural fat because the former has an attenuation similar to that of muscle and shows enhancement with intravenous administration of contrast material.
MR imaging is the most effective method of demonstrating extramedullary hematopoiesis in the epidural space and is indicated on an urgent basis when symptoms of spinal cord compression are present. On T1-weighted images, extramedullary hematopoiesis is seen as an extramedullary mass with a signal intensity slightly higher than that of the adjacent red marrow of the vertebrae. Similar findings are seen on T2-weighted images, with the signal intensity of extramedullary hematopoiesis being only slightly higher than that of bone marrow. Use of contrast material is unnecessary. T2-weighted sequences may be useful, however, to demonstrate the high signal intensity of an injured spinal cord. This high signal intensity is due to edema, myelomalacia, or gliosis of the spinal cord due to chronic compression.
The most common site of spinal epidural extramedullary hematopoiesis is posteriorly in the thoracic spine. The epidural space between the spinal dura mater and the ligaments and periosteum of the posterior spinal elements contains fat, loose connective tissue, and venous plexuses. It is widest in the posterior thoracic spine and is the most common site for extramedullary hematopoiesis when the spinal cord is affected.
Treatment of spinal cord compression due to extramedullary hematopoiesis may be surgical decompression, radiation therapy, or transfusion. Surgery has the advantage of providing tissue and allowing the histologic diagnosis to be confirmed, but it risks recurrence. Furthermore, many patients are anemic and have cardiovascular problems that make them poor surgical candidates. Blood transfusions correct the anemia and suppress the extramedullary hematopoiesis. They are most effective when used as an adjunct to surgery.
Radiation therapy is usually the treatment of choice for patients with extramedullary hematopoiesis that causes spinal cord compression. There is a rapid response to low doses, often in the range of 10–30 Gy. Radiation therapy may also be combined with either surgery or blood transfusion. The main disadvantages of radiation therapy are that tissue is not obtained for histologic verification of the diagnosis and that additional hematopoietic tissue is destroyed. However, long-term follow-up after treatment with irradiation suggests durable control of the spinal cord compressive effects.
Suggested Readings
Aydingöz Ü, Oto A, Cila A. Spinal cord compression due to epidural extramedullary haematopoiesis in thalassaemia: MRI. Neuroradiology 1997; 39:870–872.
Chaljub G, Guinto FC Jr, Crow WN, Kumar R. MRI diagnosis of spinal cord compression in beta-thalassemia. Spine 1991; 16:583–584.
Jackson DV, Randall ME, Richards F. Spinal cord compression due to extramedullary hematopoiesis in thalassemia: long-term follow-up after radiotherapy. Surg Neurol 1988; 29:389–392.
Lau SK, Chan CK, Chow YYN. Cord compression due to extramedullary hemopoiesis in a patient with thalassemia. Spine 1994; 19:2467–2470.
Pantongrag-Brown L, Suwanwela N. Case report: chronic spinal cord compression from extramedullary haematopoiesis in thalassaemia—MRI findings. Clin Radiol 1992; 46:281–283.
Papavasiliou C. Clinical expressions of the expansion of the bone marrow in the chronic anemias: the role of radiotherapy. Int J Radiat Oncol Biol Phys 1994; 28:605–612.
Papavasiliou C, Gouliamos A, Vlahos L, et al. CT and MRI of symptomatic spinal involvement by extramedullary haemopoiesis. Clin Radiol 1990; 42:91–92.
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Case 6 |
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Discussion
Benign mucous membrane pemphigoid (BMMP) is a relatively rare disease of unknown cause. The characteristic histologic feature is the presence of subepidermal bullae without acantholysis. This feature distinguishes BMMP from epidermolysis bullosa in which the bullae are intraepidermal.
Epidermolysis bullosa is a group of inherited and acquired disorders in which blistering of the skin and mucous membranes occurs in response to minor trauma. The disease is subdivided by the layer of skin involved in the separation. In epidermolysis bullosa dystrophica, the division occurs within the dermis and may lead to scarring.
The skin and esophagus are involved most frequently in patients with epidermolysis bullosa because these are the most frequent sites of trauma. Esophageal lesions are seen most often at sites of relative stasis, the aortic knob, carina, and gastroesophageal junction. Mucosa trauma leads to the formation of bullae, which may heal with scarring and stenoses.
Patients with BMMP typically present in the 4th decade of life, and there is a female preponderance. BMMP is manifested by inflammatory subepidermal bullae with a predilection for the mucous membranes, especially the oral mucosa and conjunctiva. The oral mucosa is involved in almost all patients, whereas involvement of the conjunctiva is seen in 61%–71% of patients. In as many as 25% of patients, the disease may progress to cicatricial conjunctivitis, which leads to blindness. Esophageal involvement is seen in 2%–13% of patients.
Involvement of the esophagus in BMMP was classified into two types by Al-Kutoubi et al (1984). In the early stage of the disease, thin smooth webs, which usually arise from the anterior aspect of the esophagus, are seen. Similar webs may be seen in the Plummer-Vinson syndrome and in the bullous dermatoses of pemphigus vulgaris, bullous pemphigoid, and epidermolysis bullosa dystrophica.
The second form of esophageal involvement in BMMP consists of stenoses, which may be of variable length. These stenoses consist of smooth narrowing of the esophagus, and progression to complete obstruction has been reported. The differential diagnosis for this appearance is broad and includes strictures secondary to ingestion of caustic agents such as lye, peptic esophagitis, irradiation, the bullous dermatoses, Crohn disease, sarcoidosis, and infection.
Treatment of esophageal involvement with BMMP is more successful in the early stages. Soft webs may be dilated endoscopically. However, trauma from endoscopy may cause bullae to form, although this is not as common in BMMP as in epidermolysis bullosa dystrophica. Once long stenoses and strictures have developed, successful bouginage is unlikely. Patients become increasingly malnourished and may suffer episodes of obstruction or aspiration.
Cutaneous disorders that involve the esophagus include epidermolysis bullosa dystrophica, pemphigus vulgaris, and BMMP. In epidermolysis bullosa dystrophica, cutaneous and mucosal blistering begin soon after birth. Esophageal lesions are seen in the distal esophagus as well as the proximal esophagus. Esophageal involvement by pemphigus vulgaris is very rare.
Suggested Readings
Al-Kutoubi MA, Eliot C. Oesophageal involvement in benign mucous membrane pemphigoid. Clin Radiol 1984; 35:131–135.
Goldin E, Lijovetzky G. Esophageal involvement by pemphigus vulgaris. Am J Gastroenterol 1985; 80: 828–830.
Karasick S, Mapp E, Karasick D. Esophageal involvement in benign mucous membrane pemphigoid. J Can Assoc Radiol 1981; 32:247–248.
Mauro MA, Parker LA, Hartley WS, Renner JB, Mauro PM. Epidermolysis bullosa: radiographic findings in 16 cases. AJR Am J Roentgenol 1987; 149:925–927.
Tishler JM, Han SY, Helman CA. Esophageal involvement in epidermolysis bullosa dystrophica. AJR Am J Roentgenol 1983; 141:1283–1286.
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Case 7 |
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Discussion
The most common primary malignant tumor of the retroperitoneum is liposarcoma. These tumors arise most frequently anterior to the spine and psoas muscles, although they may also occur in the paraspinal or posterior pararenal space. The average age of presentation of patients with liposarcoma is in the 7th decade of life; men are affected more often than women. Clinical presentation includes abdominal pain, weight loss, anemia, and a palpable mass. In the series reported by Lane et al (1989), liposarcomas averaged 20 cm in diameter.
The appearance of liposarcoma at CT depends on the degree of differentiation of the tumor. Lipogenic liposarcomas are composed predominantly of malignant lipoblasts. They contain a large amount of lipid and only scanty myxoid matrix. They appear on CT scans as fatty masses with streaks of high attenuation that are too thick and poorly defined to be the fine septations seen in lipomas.
The most common liposarcomas are the myxoid tumors. They contain a large amount of connective tissue mucin but relatively little lipid. The attenuation values of these tumors vary greatly, from near that of water to that of muscle.
Undifferentiated liposarcomas show marked cellular pleomorphism and contain little mucin or lipid. These undifferentiated liposarcomas cannot be distinguished from other soft-tissue retroperitoneal sarcomas by their imaging features.
Malignant fibrous histiocytoma is the second most common primary retroperitoneal malignancy. The clinical presentation, age, and gender distribution of these patients are similar to those for patients with liposarcoma. The tumors typically have attenuation values similar to that of muscle, and approximately 25% contain dystrophic calcification.
The third most common primary retroperitoneal malignancy is leiomyosarcoma. These tumors may arise from the smooth muscle component of any retroperitoneal structure including bowel or the wall of a vein such as the inferior vena cava. Abdominal pain is the usual presenting symptom, although a palpable abdominal mass is usually present. In the series reported by Lane et al (1989), leiomyosarcomas averaged 11.0 cm in diameter at presentation. Patients with leiomyosarcomas are more likely to be female than male, which is reverse from the gender distribution for liposarcoma and malignant fibrous histiocytoma, which occur more frequently in men. The peak prevalence for retroperitoneal leiomyosarcomas is in the 5th and 6th decades of life.
Hartman et al (1992) described three major growth patterns of retroperitoneal leiomyosarcomas: completely extravascular, completely intravascular, and those that have both extra- and intraluminal components. In their series, the completely extravascular pattern was the most common, occurring in 62% of cases. Completely intravascular tumors were found in only 5% of cases, whereas an extra- and intraluminal pattern was present in 33% of cases.
The radiographic appearance of a retroperitoneal leiomyosarcoma is a large, soft-tissue mass. At US, the tumor mass is isoechoic relative to the liver, but cystic areas are often seen. On CT scans, leiomyosarcomas appear as large masses with attenuation values similar to that of muscle. Low-attenuation areas representing areas of necrosis may be seen. The multiplanar capabilities of MR imaging may be especially valuable for defining large tumors. The appearance of leiomyosarcoma on MR images is variable, depending on the degree of necrosis within the tumor. T1-weighted images demonstrate low-signal-intensity areas corresponding to tissue necrosis. T2-weighted images show an intermediate to high signal intensity due to the high water content in these cystic areas.
The primary modality used in the detection and staging of a retroperitoneal mass is CT. Unless characteristic features such as fat or formed bone elements are present, a confident diagnosis cannot be made. Treatment is surgical resection. Prognosis depends on the age of the patient, size of the tumor, and ability to completely resect the lesion.
Suggested Readings
Hartman DS, Hayes WS, Choyke PL, Tibbetts GP. Leiomyosarcoma of the retroperitoneum and inferior vena cava: radiologic-pathologic correlation. RadioGraphics 1992; 12:1203–1220.
Hill MA, Mera R, Levine EA. Leiomyosarcoma: a 45-year review at Charity Hospital, New Orleans. Am Surg 1998; 64:53–61.
Hines OJ, Nelson S, Quinones-Baldrich WJ, Eilber FR. Leiomyosarcoma of the inferior vena cava: prognosis and comparison with leiomyosarcoma of other anatomic sites. Cancer 1999; 85:1077–1083.
Lane RH, Stephens DH, Reiman HM. Primary retroperitoneal neoplasms: CT findings in 90 cases with clinical and pathologic correlation. AJR Am J Roentgenol 1989; 152:83–89.
Papanicolaou N, Yoder IS, Lee MJ. Primary retroperitoneal neoplasms: how close can we come in making the correct diagnosis. Urol Radiol 1992; 14:221–228.
Wells FC, Naylor CPE, Dunn DC. Leiomyoma of the renal vein. J R Soc Med 1981; 74:542–545.
Wile AG, Evans HL, Romsdahl MM. Leiomyosarcoma of soft tissue: a clinicopathologic study. Cancer 1981; 48:1022-1032.
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Case 8 |
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Radiography of the tibia demonstrated a geographic lesion eccentrically located within the distal tibia (Fig 17a). The mass extended through the tibial cortex into the soft tissues (Fig 17b). The periosteum was elevated at the cortical margins with peripheral new bone formation that partly circumscribed the soft-tissue mass, a finding suggestive of an intraosseous origin rather than osseous invasion from an extraosseous tumor.
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Discussion
Neurofibromatosis is an autosomal dominant disorder of neuroectodermal and mesenchymal origin. The disease is characterized by café au lait spots, cutaneous tumors, and multiple tumors of the spinal or cranial nerves. There is an increased prevalence of pheochromocytomas, renal vascular lesions, tumors of the central nervous system, and cystic lung disease in these patients.
A variety of bone abnormalities are found in patients with neurofibromatosis. The skull is often large, and portions of the cranial vault may be absent, especially the greater or lesser wings of the sphenoid bone. Enlargement of the auditory or optic canals occurs as a result of cranial nerve tumors. Intervertebral foramina may be enlarged by tumors of the peripheral nerves. The ribs may be notched, thin, or ribbonlike in configuration.
The development of a malignant peripheral nerve sheath tumor (MPNST) is the most serious complication of neurofibromatosis and is often fatal. MPNSTs were reported in 4.6% of patients with neurofibromatosis type 1 seen at the Mayo Clinic—4,600 times the frequency with which these tumors were seen in the general clinic population. Conversely, a review of 120 patients with MPNSTs by Ducatman et al (1986) revealed that 52% had neurofibromatosis. Most cases of MPNST occur in patients between 20 and 50 years of age and who have had the fully developed disease for at least 10–20 years. The peak prevalence of MPNST in patients with neurofibromatosis is in the 3rd decade of life, whereas the peak prevalence of sporadic MPNST is in the 5th decade of life. The nerves most frequently affected by MPNST are the major nerves such as the sciatic nerve, sacral nerve, and brachial plexus. A modest female gender predilection has been reported.
Skeletal involvement by MPNST is uncommon and usually results from secondary invasion. Primary intraosseous origin is rare, reflecting the low density of sensory nerve fibers in bone. By far, the most common site for intraosseous MPNST is the mandible.
The most common presenting complaint is an enlarging soft-tissue mass. Because MPNSTs are usually painless, the tumor mass may be present as long as several years before the patient seeks medical attention. The clinical course includes local tumor recurrence, perineural spread (often a great distance from the primary tumor), and pulmonary metastases.
Treatment consists primarily of surgical excision. Extensive local excision or even amputation may be required (Fig 19). Adjuvant radiation therapy, even in the presence of clear surgical margins, seems helpful. Despite aggressive therapy, the prognosis of MPNST is poor.
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Ducatman B, Scheithauer B, Piepfras D, Reiman J, Ilstrup O. Malignant peripheral sheath tumors: a clinicopathologic study of 120 cases. Cancer 1986; 57:2006–2021.
Khan RJK, Asgher J, Sohail MT, Chughtai AS. Primary intraosseous malignant peripheral nerve sheath tumor: a case report and review of the literature. Pathology 1998; 30:237–241.
Terry DG, Sauser DD, Gordon MD. Intraosseous malignant peripheral nerve sheath tumor in a patient with neurofibromatosis. Skeletal Radiol 1998; 27: 346–349.
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