Figure 2b. Small bone sarcoidosis in a 53-year-old woman with a 12-year history of painful swelling of the digits. (a) Axial T2-weighted MR image (repetition time msec/echo time msec = 4,000/85) demonstrates swelling of the fifth finger with destruction of the cortex of the proximal phalanx. Periosseous extension of presumed sarcoidosis nodules with intermediate signal intensity is also seen (arrow). (b) Axial fat-saturated proton-density-weighted MR image (1,200/20) of the digits reveals a conglomerate nodular mass with bright signal intensity infiltrating the fifth proximal phalanx and destroying the cortex. (c) Coronal T1-weighted MR image (500/20) demonstrates a low-signal-intensity intramedullary mass of the fifth digit with fine perpendicular lines extending from the ghost of the cortex. Although this finding resembles periosteal reaction, it may represent periosseous extension of granulomas separated by fibroblasts and collagen. (d) Coronal fat-saturated proton-density-weighted MR image (2,000/22) also demonstrates fine perpendicular lines extending from the intramedullary lesion.