Cutaneous Syncytial Myoepithelioma

• DOI: 10.1097/pas.0b013e3182772bba
• Publication Date: 2013-04-13T15:35:37Z
• Authors: Vickie Y. Jo; Cristina R. Anton...; Lei Zhang; Paola Dal Cin; Jason L. Hornick; Christopher D.M. ...
• Keywords: Merkel cell; Nuclear atypia; Myoepithelioma

Cutaneous myoepithelial tumors demonstrate heterogenous morphologic and immunophenotypic features. We previously described, in brief, 7 cases of cutaneous myoepithelioma showing solid syncytial growth ovoid, spindled, or histiocytoid cells. now present the clinicopathologic features a series 38 this distinctive variant, which were diagnosed between 1997 2012 (mostly seen consultation). There 27 men 11 women, with median age 39 years (range, 2 mo to 74 y). Primary anatomic sites upper extremity (11, including on hand), limb girdle (3), lower (14; 3 foot), back (6), face (2), chest (1), buttock (1); typical presentation was as either polypoid papular lesion. Tumors well circumscribed centered dermis ranged size from 0.3 2.7 cm (median 0.8 cm). Microscopically all showed sheet-like uniformly sized ovoid spindled cells palely eosinophilic cytoplasm. Nuclei vesicular fine chromatin small inconspicuous nucleoli exhibited minimal no atypia. Mitoses 0 4 per 10 HPF; 28 mitoses. Necrosis lymphovascular invasion consistently absent. Adipocytic metaplasia, appearing superficial fat entrapped within tumor, 12 cases. Chondro-osseous differentiation 1 tumor. All examined diffusely positive for EMA, majority diffuse staining S-100 protein (5 focal staining). Keratin 33 rare other also positivity GFAP (14/33), SMA (9/13), p63 (6/11). Most lesions treated by local excision. The tested (14/17; 82%) fluorescence situ hybridization EWSR1 gene rearrangement; testing potential fusion partners (PBX1, ZNF444, POU5F1, DUX4, ATF1, CREB1, NR4A3, DDIT3, NFATc2) negative EWSR1-rearranged tumors. No FUS rearrangement detected lacking rearrangement. Follow-up information is available 21 patients (mean follow-up 15 mo). One patient deep margin developed recurrence 51 months after initial biopsy. information, who had margins, are alive evidence disease reported metastases. In summary, morphologically distinct variant that more frequently affects men, occurs over wide range, usually presents extremities. and, unlike most neoplasms, keratin infrequent. nearly likely involves novel partner. Prior reports describe some risk metastasis tumors; however, appears behave benign manner only rarely recurs locally.