By computed tomography, there is a poorly circumscribed, heterogeneous soft tissue mass, with a signal intensity similar to skeletal muscle. The fact that the lesion may be bilateral, helps eliminate a sarcoma from further consideration. At US,<unk> s are depicted deep to the musculature as a multilayered pattern of hypoechoic linear areas of fat deposition intermixed with echogenic fibroelastic tissue. The mass often protrudes from the subscapular region upon shoulder abduction, allowing better delineation of the finding. Pathology findings In general, the tumor is an ill defined, nonencapsulated, rubbery, and firm, white lesion with interspersed fat. The tumors can be quite large (up to 20 cm), although most are around 5 cm.A high power photomicrograph of an<unk> . By microscopie view, there is an admixture of heavy dense bands of collagenous tissue dissected by fat and abnormal elastic fibers. The elastic fibers are often quite large and are easily identified. The elastic fibers are coarse, thick, and darkly eosinophilic, often fragmented into globules, creating a "string of pearls" or "pipe cleaner" appearance. Because of degeneration, the elastic fibers will appear as globules with a serrated or "prickled" edge. Histochemistry An elastic stain photomicrograph at high power highlighting the elastic fibers in black. The elastic fibers will be highlighted by a Weigert or von Gieson elastic stains. Differential diagnoses Given the anatomic site, a spindle cell lipoma, nuchal-type fibroma and fibromatosis colli are all included in the differential diagnosis.
Elastofibroma dorsi
Dermatofibroma
Aggressive infantile fibromatosis
Dermatofibrosarcoma protuberans
Diffuse infantile fibromatosis
Aggressive fibromatosis
Acral fibrokeratoma
Superficial acral fibromyxoma