[462] Clinicopathologic Features of Cutaneous Perineurioma and Perineurial Cell-Rich Tumors

Matthew D Cykowski, Igor Shendrik, Cynthia M Magro, Jan V Pitha, A Neil Crowson. University of Oklahoma Health Sciences Center, Oklahoma City, OK; Regional Medical Laboratories, Tulsa, OK; Weill Cornell Medical College, New York City, NY

Background: Perineuriomas are uncommon, histologically heterogeneous tumors with morphologic and immunohistochemical features that recapitulate the normal perineurium. Cutaneous perineuriomas (CPs) involving the dermis and superficial subcutis are particularly rare and may be under-recognized. This study aimed to characterize further the clinicopathologic features of CP and associated perineurial cell-rich tumors.
Design: Eleven cases were retrieved from the pathology archives at three institutions. Clinical features and routine histology were reviewed. Immunohistochemical stains performed on all cases included S-100, EMA, Actin, CD34, Glut-1, CK7, INI-1, and Collagen IV. Additional stains (e.g., claudin-1, factor XIIIa) were available for select cases.
Results: Seven CPs (4 soft tissue and 3 sclerosing variants), 2 hybrid schwannoma/perineuriomas, and 2 perineurial cell-rich neurofibromas were identified. Patients included 7 males and 4 females (median age of 48 years; range of 11 to 65 years). All but one tumor occurred in the extremities. Clinical impressions ranged from digital fibroma to verruca, epidermal cyst, ganglion cyst and fibrosis. Morphologic features were heterogeneous ranging from dermal-based, well-demarcated whorled and nested nodules with rare mitoses to larger tumors with a diffuse growth pattern and storiform or whorled arrangement of spindle cells. Several dermal tumors featured dilated lymphatics in the superficial dermis as well as a transition between thin, elongated, EMA-positive perineurial cells and epithelioid cells at the tumor periphery. All CPs were positive for EMA and Glut-1; 64% were positive for CD34, which highlighted elongated cell processes. Claudin-1 and Factor XIIIa were also positive in select dermal-based tumors. S-100 was negative in pure perineurial tumors and the INI-1 staining pattern was normal. Additional stains were largely noncontributory.
Conclusions: CP is a very rare neoplasm with an extensive differential diagnosis that arises in the extremities of predominantly middle-aged adults. The lesion may be difficult to recognize as being of perineurial origin, both clinically and histologically. We determined that dilated lymphatic channels in the superficial dermis and a peripheral transition into epithelioid cells from flattened perineurial-type cells may be helpful diagnostic clues. For confirmation, Glut-1, CD34, and claudin-1 may be useful for S-100 negative, EMA-positive dermal tumors with an epithelioid cytology.
Category: Dermatopathology

Monday, March 4, 2013 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 64, Monday Morning


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