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Multimodality Imaging of Paratesticular Neoplasms and Their Rare Mimics¹

¹ From the Departments of Radiology (S.A.A., T.A.S., S.Z.H.J.) and Pathology (F.H., J.S.A.N.), William Beaumont Hospital, 3601 W 13 Mile Rd, Royal Oak, MI 48073. Recipient of a Certificate of Merit award for an education exhibit at the 2001 RSNA scientific assembly. Received December 12, 2002; revision requested January 9, 2003, and received June 9; accepted June 9. Address correspondence to S.A.A. (e-mail: s.a.akbar@netzero.net).

View larger version (68K): [in a new window]   Figure 1a.  Diagrams illustrate the normal anatomy of the testis and testicular adnexa. (a) A dense, tightly adherent fibrous membrane, the tunica albuginea, surrounds the testis. The tunica albuginea invaginates the interior of the testis posteriorly to form an incomplete vertical septum, the mediastinum testis. Numerous fibrous septa radiate from the mediastinum toward the surface of the gland and separate the organ into multiple cone-shaped lobules that contain convoluted seminiferous tubules. As they approach the mediastinum, the seminiferous tubules straighten and unite to form 20-30 larger ducts, which then enter the fibrous tissue of the mediastinum and form an anastomotic network of channels that constitutes the rete testis. At the upper end of the mediastinum, the channels of the rete testis perforate the tunica albuginea and form 12-15 ducts called the efferent ductules, which enter the head of the epididymis. The epididymis, which connects the testis with the vas deferens, is attached to the testis posteriorly. It consists of three anatomic segments: the head (globus major), the body (corpus epididymidis), and the tail (globus minor). (b) The testis and epididymis are loosely invested by a serous membrane, the tunica vaginalis. Derived from the processus vaginalis of the peritoneum, this membrane consists of visceral and parietal layers. Three closely applied fascial layers surround the tunica vaginalis and extend cranially to envelop the structures of the spermatic cord: the internal spermatic fascia, the cremasteric fascia, and the external spermatic fascia. The internal spermatic fascia is a continuation of the transversalis fascia. The cremasteric layer consists of scattered muscle bundles within a fascial membrane that corresponds to the internal oblique muscle and its fascia. The external spermatic fascia is continuous at the superficial inguinal ring with the deep fascia that cover the aponeurosis of the external oblique muscle. The external covering of the testis is the scrotum, which consists of two layers, the tunica dartos and the skin. The tunica dartos is a highly vascular membrane containing a thin layer of nonstriated muscle fibers. In the midline, a septum extends inward from the dartos layer to divide the scrotal pouch into two cavities for the testes. (Fig 1b reprinted, with permission, from reference 1.) (c) Vestigial remnants of the testis, epididymis, and vas deferens. (Fig 1c reprinted, with permission, from reference 2.)

View larger version (86K): [in a new window]   Figure 1b.  Diagrams illustrate the normal anatomy of the testis and testicular adnexa. (a) A dense, tightly adherent fibrous membrane, the tunica albuginea, surrounds the testis. The tunica albuginea invaginates the interior of the testis posteriorly to form an incomplete vertical septum, the mediastinum testis. Numerous fibrous septa radiate from the mediastinum toward the surface of the gland and separate the organ into multiple cone-shaped lobules that contain convoluted seminiferous tubules. As they approach the mediastinum, the seminiferous tubules straighten and unite to form 20-30 larger ducts, which then enter the fibrous tissue of the mediastinum and form an anastomotic network of channels that constitutes the rete testis. At the upper end of the mediastinum, the channels of the rete testis perforate the tunica albuginea and form 12-15 ducts called the efferent ductules, which enter the head of the epididymis. The epididymis, which connects the testis with the vas deferens, is attached to the testis posteriorly. It consists of three anatomic segments: the head (globus major), the body (corpus epididymidis), and the tail (globus minor). (b) The testis and epididymis are loosely invested by a serous membrane, the tunica vaginalis. Derived from the processus vaginalis of the peritoneum, this membrane consists of visceral and parietal layers. Three closely applied fascial layers surround the tunica vaginalis and extend cranially to envelop the structures of the spermatic cord: the internal spermatic fascia, the cremasteric fascia, and the external spermatic fascia. The internal spermatic fascia is a continuation of the transversalis fascia. The cremasteric layer consists of scattered muscle bundles within a fascial membrane that corresponds to the internal oblique muscle and its fascia. The external spermatic fascia is continuous at the superficial inguinal ring with the deep fascia that cover the aponeurosis of the external oblique muscle. The external covering of the testis is the scrotum, which consists of two layers, the tunica dartos and the skin. The tunica dartos is a highly vascular membrane containing a thin layer of nonstriated muscle fibers. In the midline, a septum extends inward from the dartos layer to divide the scrotal pouch into two cavities for the testes. (Fig 1b reprinted, with permission, from reference 1.) (c) Vestigial remnants of the testis, epididymis, and vas deferens. (Fig 1c reprinted, with permission, from reference 2.)

View larger version (77K): [in a new window]   Figure 1c.  Diagrams illustrate the normal anatomy of the testis and testicular adnexa. (a) A dense, tightly adherent fibrous membrane, the tunica albuginea, surrounds the testis. The tunica albuginea invaginates the interior of the testis posteriorly to form an incomplete vertical septum, the mediastinum testis. Numerous fibrous septa radiate from the mediastinum toward the surface of the gland and separate the organ into multiple cone-shaped lobules that contain convoluted seminiferous tubules. As they approach the mediastinum, the seminiferous tubules straighten and unite to form 20-30 larger ducts, which then enter the fibrous tissue of the mediastinum and form an anastomotic network of channels that constitutes the rete testis. At the upper end of the mediastinum, the channels of the rete testis perforate the tunica albuginea and form 12-15 ducts called the efferent ductules, which enter the head of the epididymis. The epididymis, which connects the testis with the vas deferens, is attached to the testis posteriorly. It consists of three anatomic segments: the head (globus major), the body (corpus epididymidis), and the tail (globus minor). (b) The testis and epididymis are loosely invested by a serous membrane, the tunica vaginalis. Derived from the processus vaginalis of the peritoneum, this membrane consists of visceral and parietal layers. Three closely applied fascial layers surround the tunica vaginalis and extend cranially to envelop the structures of the spermatic cord: the internal spermatic fascia, the cremasteric fascia, and the external spermatic fascia. The internal spermatic fascia is a continuation of the transversalis fascia. The cremasteric layer consists of scattered muscle bundles within a fascial membrane that corresponds to the internal oblique muscle and its fascia. The external spermatic fascia is continuous at the superficial inguinal ring with the deep fascia that cover the aponeurosis of the external oblique muscle. The external covering of the testis is the scrotum, which consists of two layers, the tunica dartos and the skin. The tunica dartos is a highly vascular membrane containing a thin layer of nonstriated muscle fibers. In the midline, a septum extends inward from the dartos layer to divide the scrotal pouch into two cavities for the testes. (Fig 1b reprinted, with permission, from reference 1.) (c) Vestigial remnants of the testis, epididymis, and vas deferens. (Fig 1c reprinted, with permission, from reference 2.)

View larger version (123K): [in a new window]   Figure 2a.  Adenomatoid tumor of the epididymis. (a) US image shows an approximately 1 x 2-cm fluid-filled structure with septa within the right hemiscrotum (arrow). The structure is separate from the testicle (T), which has a normal appearance. No flow was seen within the septated structure at color Doppler US. (b) Photograph of the cut surface of the gross specimen reveals a white-tan, homogeneous solid nodule. Scale is in centimeters.

View larger version (143K): [in a new window]   Figure 2b.  Adenomatoid tumor of the epididymis. (a) US image shows an approximately 1 x 2-cm fluid-filled structure with septa within the right hemiscrotum (arrow). The structure is separate from the testicle (T), which has a normal appearance. No flow was seen within the septated structure at color Doppler US. (b) Photograph of the cut surface of the gross specimen reveals a white-tan, homogeneous solid nodule. Scale is in centimeters.

View larger version (126K): [in a new window]   Figure 3a.  Epididymal leiomyoma. (a) Longitudinal US image of the left hemiscrotum shows a large, solid extratesticular mass (M) that displaces the testicle (T) inferiorly. The mass has a heterogeneous echotexture. (b) Photograph of the gross specimen shows a white, firm, ill-defined tumor of the epididymis (arrow). Scale is in centimeters.

View larger version (96K): [in a new window]   Figure 3b.  Epididymal leiomyoma. (a) Longitudinal US image of the left hemiscrotum shows a large, solid extratesticular mass (M) that displaces the testicle (T) inferiorly. The mass has a heterogeneous echotexture. (b) Photograph of the gross specimen shows a white, firm, ill-defined tumor of the epididymis (arrow). Scale is in centimeters.

View larger version (102K): [in a new window]   Figure 4a.  Lipoma of the spermatic cord. (a) US image demonstrates an echogenic solid mass (M) superior to the left testicle. (b) CT scan demonstrates the mass (M) with fat attenuation in the left inguinal canal. (c) T1-weighted MR image obtained in a different patient demonstrates a mass (M) in the right inguinal canal. The mass has increased signal intensity, a finding that is compatible with fat.

View larger version (154K): [in a new window]   Figure 4b.  Lipoma of the spermatic cord. (a) US image demonstrates an echogenic solid mass (M) superior to the left testicle. (b) CT scan demonstrates the mass (M) with fat attenuation in the left inguinal canal. (c) T1-weighted MR image obtained in a different patient demonstrates a mass (M) in the right inguinal canal. The mass has increased signal intensity, a finding that is compatible with fat.

View larger version (149K): [in a new window]   Figure 4c.  Lipoma of the spermatic cord. (a) US image demonstrates an echogenic solid mass (M) superior to the left testicle. (b) CT scan demonstrates the mass (M) with fat attenuation in the left inguinal canal. (c) T1-weighted MR image obtained in a different patient demonstrates a mass (M) in the right inguinal canal. The mass has increased signal intensity, a finding that is compatible with fat.

View larger version (147K): [in a new window]   Figure 5a.  Hemangioma. (a) Coronal T1-weighted MR image demonstrates a lobulated mass (arrows) that involves the inferior aspect of the hemiscrotum. The lesion has intermediate signal intensity and is confined to the lower scrotum. (b) Axial fast spin-echo T2-weighted MR image shows that the lesion is separate from the adjacent testicle and epididymis. The hyperintense areas represent stagnant blood. Several small foci of signal void (arrowheads) likely represent thrombus. (c) Sagittal inversion-recovery MR image reveals a dominant feeding vessel (long arrow) that courses along the posterior aspect of the testicle and simulates a dilated testicular vein. Punctate foci of hypointense thrombus (short arrows) are seen within the hemangioma. (Figure 5 reprinted, with permission, from reference 8.)

View larger version (151K): [in a new window]   Figure 5b.  Hemangioma. (a) Coronal T1-weighted MR image demonstrates a lobulated mass (arrows) that involves the inferior aspect of the hemiscrotum. The lesion has intermediate signal intensity and is confined to the lower scrotum. (b) Axial fast spin-echo T2-weighted MR image shows that the lesion is separate from the adjacent testicle and epididymis. The hyperintense areas represent stagnant blood. Several small foci of signal void (arrowheads) likely represent thrombus. (c) Sagittal inversion-recovery MR image reveals a dominant feeding vessel (long arrow) that courses along the posterior aspect of the testicle and simulates a dilated testicular vein. Punctate foci of hypointense thrombus (short arrows) are seen within the hemangioma. (Figure 5 reprinted, with permission, from reference 8.)

View larger version (143K): [in a new window]   Figure 5c.  Hemangioma. (a) Coronal T1-weighted MR image demonstrates a lobulated mass (arrows) that involves the inferior aspect of the hemiscrotum. The lesion has intermediate signal intensity and is confined to the lower scrotum. (b) Axial fast spin-echo T2-weighted MR image shows that the lesion is separate from the adjacent testicle and epididymis. The hyperintense areas represent stagnant blood. Several small foci of signal void (arrowheads) likely represent thrombus. (c) Sagittal inversion-recovery MR image reveals a dominant feeding vessel (long arrow) that courses along the posterior aspect of the testicle and simulates a dilated testicular vein. Punctate foci of hypointense thrombus (short arrows) are seen within the hemangioma. (Figure 5 reprinted, with permission, from reference 8.)

View larger version (109K): [in a new window]   Figure 6a.  Epididymal papillary cystadenoma. (a) US image demonstrates a predominantly solid ovoid mass (M) containing small cystic spaces and located in the head of the epididymis and superior to the testes. (b) US image demonstrates a cystic structure with small papillary projections (arrow). (Case courtesy of Peter L. Choyke, MD, Department of Radiology, Warren G. Magnuson Clinical Center, National Cancer Institute, Bethesda, Maryland.)

View larger version (98K): [in a new window]   Figure 6b.  Epididymal papillary cystadenoma. (a) US image demonstrates a predominantly solid ovoid mass (M) containing small cystic spaces and located in the head of the epididymis and superior to the testes. (b) US image demonstrates a cystic structure with small papillary projections (arrow). (Case courtesy of Peter L. Choyke, MD, Department of Radiology, Warren G. Magnuson Clinical Center, National Cancer Institute, Bethesda, Maryland.)

View larger version (139K): [in a new window]   Figure 7a.  Fibrous pseudotumor. (a) US image shows a hypoechoic mass (M) in the left supratesticular region. T = testicle. At surgery, this finding proved to be benign fibrous pseudotumor. (b) Photograph of the gross specimen demonstrates fibrosis of the epidermal head and adjacent albuginea. The cut surface of the epidermal head is gray-white, fibrotic, and cystic (arrow). The testicle is unremarkable. Scale is in centimeters.

View larger version (140K): [in a new window]   Figure 7b.  Fibrous pseudotumor. (a) US image shows a hypoechoic mass (M) in the left supratesticular region. T = testicle. At surgery, this finding proved to be benign fibrous pseudotumor. (b) Photograph of the gross specimen demonstrates fibrosis of the epidermal head and adjacent albuginea. The cut surface of the epidermal head is gray-white, fibrotic, and cystic (arrow). The testicle is unremarkable. Scale is in centimeters.

View larger version (122K): [in a new window]   Figure 8a.  Sclerosing lipogranuloma. Spin-echo T1-weighted (a), turbo spin-echo T2-weighted (b), and contrast material-enhanced fat-saturated gradient-echo (c) MR images demonstrate diffuse enlargement and heterogeneity of the right epididymis with abnormal enhancement (arrow). There is adjacent scrotal skin thickening. Bilateral hydroceles are also seen.

View larger version (120K): [in a new window]   Figure 8b.  Sclerosing lipogranuloma. Spin-echo T1-weighted (a), turbo spin-echo T2-weighted (b), and contrast material-enhanced fat-saturated gradient-echo (c) MR images demonstrate diffuse enlargement and heterogeneity of the right epididymis with abnormal enhancement (arrow). There is adjacent scrotal skin thickening. Bilateral hydroceles are also seen.

View larger version (120K): [in a new window]   Figure 8c.  Sclerosing lipogranuloma. Spin-echo T1-weighted (a), turbo spin-echo T2-weighted (b), and contrast material-enhanced fat-saturated gradient-echo (c) MR images demonstrate diffuse enlargement and heterogeneity of the right epididymis with abnormal enhancement (arrow). There is adjacent scrotal skin thickening. Bilateral hydroceles are also seen.

View larger version (123K): [in a new window]   Figure 9a.  Embryonal rhabdomyosarcoma. (a) US image shows an approximately 3.8 x 1.6-cm isoechoic mass (arrow) adjacent to and encircling the right testicle. The testicle and epididymis are of normal echogenicity. Extensive flow was noted at color Doppler US. (b) T2-weighted MR image demonstrates a large mass that is isointense relative to the testis (arrow). Fibrous septa and lobulations are seen within the mass. The testis is anterolaterally displaced. A small hydrocele is also present. (Case courtesy of D. Gibson, MD, William Beaumont Hospital, Royal Oak, Michigan.) (c) Photograph of the gross specimen of a rhabdomyosarcoma that arose in the spermatic cord of a 5-year-old boy shows a white, glistening, encapsulated tumor with a lobular cut surface (arrow). Scale is in centimeters.

View larger version (122K): [in a new window]   Figure 9b.  Embryonal rhabdomyosarcoma. (a) US image shows an approximately 3.8 x 1.6-cm isoechoic mass (arrow) adjacent to and encircling the right testicle. The testicle and epididymis are of normal echogenicity. Extensive flow was noted at color Doppler US. (b) T2-weighted MR image demonstrates a large mass that is isointense relative to the testis (arrow). Fibrous septa and lobulations are seen within the mass. The testis is anterolaterally displaced. A small hydrocele is also present. (Case courtesy of D. Gibson, MD, William Beaumont Hospital, Royal Oak, Michigan.) (c) Photograph of the gross specimen of a rhabdomyosarcoma that arose in the spermatic cord of a 5-year-old boy shows a white, glistening, encapsulated tumor with a lobular cut surface (arrow). Scale is in centimeters.

View larger version (127K): [in a new window]   Figure 9c.  Embryonal rhabdomyosarcoma. (a) US image shows an approximately 3.8 x 1.6-cm isoechoic mass (arrow) adjacent to and encircling the right testicle. The testicle and epididymis are of normal echogenicity. Extensive flow was noted at color Doppler US. (b) T2-weighted MR image demonstrates a large mass that is isointense relative to the testis (arrow). Fibrous septa and lobulations are seen within the mass. The testis is anterolaterally displaced. A small hydrocele is also present. (Case courtesy of D. Gibson, MD, William Beaumont Hospital, Royal Oak, Michigan.) (c) Photograph of the gross specimen of a rhabdomyosarcoma that arose in the spermatic cord of a 5-year-old boy shows a white, glistening, encapsulated tumor with a lobular cut surface (arrow). Scale is in centimeters.

View larger version (123K): [in a new window]   Figure 10a.  Liposarcoma. (a, b) T1-weighted (a) and T2-weighted (b) MR images of the scrotum demonstrate a large mass (M) that represents recurrent scrotal liposarcoma. The mass has low to intermediate signal intensity on the T1-weighted image and increased signal intensity on the T2-weighted image. Some increased signal intensity is noted within the mass on the T1-weighted image (arrow), a finding that is consistent with fat. The scrotal wall and testicle are not involved. (c) Photograph of the gross specimen shows a yellow-tan, glistening, well-circumscribed tumor that arises from the spermatic cord (arrow). Scale is in centimeters.

View larger version (139K): [in a new window]   Figure 10b.  Liposarcoma. (a, b) T1-weighted (a) and T2-weighted (b) MR images of the scrotum demonstrate a large mass (M) that represents recurrent scrotal liposarcoma. The mass has low to intermediate signal intensity on the T1-weighted image and increased signal intensity on the T2-weighted image. Some increased signal intensity is noted within the mass on the T1-weighted image (arrow), a finding that is consistent with fat. The scrotal wall and testicle are not involved. (c) Photograph of the gross specimen shows a yellow-tan, glistening, well-circumscribed tumor that arises from the spermatic cord (arrow). Scale is in centimeters.

View larger version (110K): [in a new window]   Figure 10c.  Liposarcoma. (a, b) T1-weighted (a) and T2-weighted (b) MR images of the scrotum demonstrate a large mass (M) that represents recurrent scrotal liposarcoma. The mass has low to intermediate signal intensity on the T1-weighted image and increased signal intensity on the T2-weighted image. Some increased signal intensity is noted within the mass on the T1-weighted image (arrow), a finding that is consistent with fat. The scrotal wall and testicle are not involved. (c) Photograph of the gross specimen shows a yellow-tan, glistening, well-circumscribed tumor that arises from the spermatic cord (arrow). Scale is in centimeters.

View larger version (133K): [in a new window]   Figure 11.  Leiomyosarcoma. Axial CT scan demonstrates a predominantly homogeneous mass (arrow) that is isoattenuating relative to muscle and contains some heterogeneous components. The mass arises from the left spermatic cord.

View larger version (138K): [in a new window]   Figure 12a.  Malignant schwannoma. (a) US image demonstrates a 1.3 x 1-cm heterogeneous mass (arrow) that involves the scrotal wall. The mass is hypoechoic internally and more echogenic peripherally. T = testicle. (b) Photograph of the gross specimen of a schwannoma that was removed from a 79-year-old man shows a pink-tan, rubbery, sharply circumscribed tumor. Scale is in centimeters.

View larger version (155K): [in a new window]   Figure 12b.  Malignant schwannoma. (a) US image demonstrates a 1.3 x 1-cm heterogeneous mass (arrow) that involves the scrotal wall. The mass is hypoechoic internally and more echogenic peripherally. T = testicle. (b) Photograph of the gross specimen of a schwannoma that was removed from a 79-year-old man shows a pink-tan, rubbery, sharply circumscribed tumor. Scale is in centimeters.

View larger version (165K): [in a new window]   Figure 13a.  Malignant fibrous histiocytoma. (a) US images demonstrate a heterogeneous mass with mixed echogenicity. Because of its large size, the mass was difficult to separate from the testicle. At surgery the testicle proved to be separate from the mass. Marked increased flow was seen at color Doppler US. (b) Photograph of the gross specimen shows a yellow-tan, glistening, bulging tumor that arises in the spermatic cord. The adjacent testicle (arrow) appears compressed. Scale is in centimeters.

View larger version (153K): [in a new window]   Figure 13b.  Malignant fibrous histiocytoma. (a) US images demonstrate a heterogeneous mass with mixed echogenicity. Because of its large size, the mass was difficult to separate from the testicle. At surgery the testicle proved to be separate from the mass. Marked increased flow was seen at color Doppler US. (b) Photograph of the gross specimen shows a yellow-tan, glistening, bulging tumor that arises in the spermatic cord. The adjacent testicle (arrow) appears compressed. Scale is in centimeters.

View larger version (135K): [in a new window]   Figure 14a.  Pleomorphic hyalinizing angiectatic tumor. Coronal short inversion time inversion-recovery T2-weighted (a) and contrast-enhanced fat-saturated gradient-echo (b) MR images demonstrate a heterogeneously enhancing mass (arrows) with several signal voids in the midline that adheres to the right testicle. The signal voids reflect the neovascularity of the tumor owing to its angiectatic nature. Small bilateral hydroceles are also present.

View larger version (187K): [in a new window]   Figure 14b.  Pleomorphic hyalinizing angiectatic tumor. Coronal short inversion time inversion-recovery T2-weighted (a) and contrast-enhanced fat-saturated gradient-echo (b) MR images demonstrate a heterogeneously enhancing mass (arrows) with several signal voids in the midline that adheres to the right testicle. The signal voids reflect the neovascularity of the tumor owing to its angiectatic nature. Small bilateral hydroceles are also present.

View larger version (117K): [in a new window]   Figure 15.  Metastatic renal cell carcinoma. US image demonstrates a supratesticular solid mass with mixed echogenicity. Color Doppler US demonstrated markedly increased flow within the mass.

View larger version (133K): [in a new window]   Figure 16a.  Polyorchidism. (a) US image demonstrates an oval, isoechoic mass (M) with a homogeneously echogenic pattern identical to that of the left testicle (T). The mass is inferior to the left testicle and demonstrated flow comparable to that seen in the testicle at color Doppler US. (b) Turbo spin-echo T2-weighted MR image shows a left-sided oval structure (M) with homogeneous high signal intensity. The structure had intermediate signal intensity on T1-weighted images (not shown). These findings are characteristic of normal testicular tissue. The mass is surrounded by a continuous band of low signal intensity, a finding that represents the tunica albuginea. A left varicocele is also seen. T = testicle.

View larger version (142K): [in a new window]   Figure 16b.  Polyorchidism. (a) US image demonstrates an oval, isoechoic mass (M) with a homogeneously echogenic pattern identical to that of the left testicle (T). The mass is inferior to the left testicle and demonstrated flow comparable to that seen in the testicle at color Doppler US. (b) Turbo spin-echo T2-weighted MR image shows a left-sided oval structure (M) with homogeneous high signal intensity. The structure had intermediate signal intensity on T1-weighted images (not shown). These findings are characteristic of normal testicular tissue. The mass is surrounded by a continuous band of low signal intensity, a finding that represents the tunica albuginea. A left varicocele is also seen. T = testicle.

View larger version (88K): [in a new window]   Figure 17a.  Splenogonadal fusion. (a) US image demonstrates an ovoid mass (M) attached to the testicle (T). The mass has homogeneous echogenicity similar to that of the testicle. (b) Photomicrograph of splenic sinusoidal tissue is unremarkable.

View larger version (161K): [in a new window]   Figure 17b.  Splenogonadal fusion. (a) US image demonstrates an ovoid mass (M) attached to the testicle (T). The mass has homogeneous echogenicity similar to that of the testicle. (b) Photomicrograph of splenic sinusoidal tissue is unremarkable.