8 November 2006 – Case of the Week #64
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We thank Dr. Ronald M. Angeles, University of Pittsburgh, Pennsylvania (USA), for contributing this case. We invite you to contribute a Case of the Week by sending an email to NPernick@PathologyOutlines.com with microscopic images (any size, we will shrink if necessary) in JPG or GIF format, a short clinical history, your diagnosis and any other images (gross, immunostains, EM, etc.) that may be helpful or interesting. We will write the discussion (unless you want to), list you as the contributor, and send you a check for $35 (US) for your time after we send out the case. Please only send cases with a definitive diagnosis.
Case of the Week #64
A 55 year old man presented with a left hip mass. He had been bedridden for some time, but had no history of ulceration or trauma.
The prominent cells were immunoreactive for actin, focally positive for desmin, and negative for S100 and cytokeratin.
What is your diagnosis?
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Ischemic fasciitis, first described in 1992 as atypical decubital fibroplasia (Am J Surg Path 1992;16:708), is a sarcoma-like fibroblastic proliferation, usually of soft tissue overlying bony prominences, that occurs primarily in immobilized and elderly patients. It rarely occurs in young adults (Int J Gynecol Path 2004;23:65, Path Int 1998;48:160). The most common sites are the shoulder, chest wall and sacrococcygeal region.
The mass is usually 1 to 8 cm, poorly circumscribed and often myxoid. It usually involves the deep subcutis, and may extend into adjacent skeletal muscle. Ulceration is uncommon.
Microscopically, there are zones of fibrinoid necrosis and prominent myxoid areas surrounded by ectatic, thin walled vessels and proliferating fibroblasts. The endothelial cells may be atypical. The fibroblasts have degenerative features of abundant, basophilic cytoplasm, enlarged nuclei with smudged chromatin and prominent nucleoli. There may be frequent mitotic activity, but no atypical mitotic figures. Fibrin thrombi are common within peripheral vessels. There may be multivacuolated macrophages, but no lipoblasts. Fine needle aspiration shows spindled and ovoid cells with ample cytoplasm and occasional nuclear atypia (Acta Cytol 1997;41:598).
The fibroblasts are immunoreactive for vimentin, actin and CD68, with variable CD34 immunostaining. They are usually negative for keratin and desmin.
Local excision is curative, although recurrences have been described.
The differential diagnosis includes epithelioid sarcoma, myxoid liposarcoma and myxoid MFH. Epithelioid sarcoma has central necrosis, but typically occurs in young adults on the distal extremities, and is composed of cells with prominent eosinophilic cytoplasm that are keratin positive. Myxoid liposarcoma has a prominent plexiform vasculature and lipoblasts. Myxoid MFH has marked atypia, but no smudgy chromatin or fibrin thrombi. In addition, it lacks zonation.
Nat Pernick, M.D., President
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