[538] Wilm's Tumor 1 (WT1) Expression in Endocrine Mucin-Producing Sweat Gland Carcinoma (EMPSGC) – Immunohistochemical Evidence of Tumor Progression

W Shon, DR Salomao. Mayo Clinic, Rochester, MN

Background: EMPSGC is a rare, under recognized, low-grade sweat gland carcinoma that occurs predominantly in eyelids. Areas of benign eccrine cysts (hidrocystoma), atypical intraductal proliferation and mucinous carcinoma can be seen associated with EMPSGC suggesting tumor progression, similar to endocrine DCIS of the breast, which often coexists with mucinous carcinoma. WT1 protein, a transcription factor, is overexpressed in many solid tumors and it seems to play a role in oncogenesis. Its expression in skin adnexal tumors has not been studied.
Design: Computer based search performed for adnexal eyelid tumors, excluding basal cell carcinoma, 1989 to 2009, identified 11 EMPSGC. Demographic and clinical findings were obtained from pathology reports and patients electronic records. Biopsies were evaluated for several histological features. Immunohistochemistry for WT1, chromogranin, synaptophysin, ER, EMA, PCEA, CK7, CK20, p53, and MIB-1 were performed.
Results: There were 6 women and 5 men; mean age 62 years (range, 40 to 82). Most cases presented as slow-growing eyelid mass, in the lower (6) or upper (2) eyelid, medial (1) or lateral canthus (1), and eyelid NOS (1). Original diagnosis included hidradenoma (8), atypical hidradenoma (1), and eccrine carcinoma (2). Histologically, EMPSGC were characterized by dermal nodules with solid, cystic, and papillary areas. Tumor cells were uniform, polygonal shape with pale eosinophilic cytoplasm and round nuclei showing no or mild cytological atypia. Extra and intracellular mucin was observed; rare mitosis; no tumor necrosis. Areas of hidrocystoma (4), atypical intraductal proliferation (3) and mucinous carcinoma (3) were present. All tumors were positive for WT1, CK7, ER, p53 (weak), PCEA and EMA; and negative for CK20. Synaptophysin was positive in 9 cases and chromogranin in 8. Mib-1 proliferation index was low in 8 cases and moderate in 3. Of interest, strong WT1 nuclear staining was observed in all EMPSGC, including areas of mucinous carcinoma and areas of atypical intraductal proliferation. No WT1 staining was observed in areas of hidrocystoma, adjacent adnexal structures or overlying epidermis.
Conclusions: Our study shows WT1 expression in the neoplastic epithelial cells of EMPSGC, including areas of atypical intraductal proliferations and mucinous carcinoma. The absence of WT1 expression in areas of benign cyst/hidrocystoma and normal cutaneous structures, suggests that WT1 up-regulation plays a role in tumor cell proliferation and progression of EMPSGC.
Category: Dermatopathology

Monday, March 22, 2010 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 74, Monday Morning


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