Abstract:

Eccrine spiradenocarcinoma is an exceptionally rare, primary cutaneous adnexal carcinoma, typically arising from malignant transformation of a benign eccrine spiradenoma precursor. We report a case of a 72-year-old female who presented with multiple skin growths located on her left face and scalp, present for many years, but painful and enlarging over weeks. Histopathological analysis of two 6mm punch biopsies revealed a deep dermal, basaloid epithelial neoplasm with ductal structures, hyalinized basement membrane material, and islands of squamoid epithelium. A gradual transition to infiltrative confluent sheets of pleomorphic basaloid cells was observed, with prominent nucleoli, atypical mitoses, and necrosis. With immunohistochemistry, benign and malignant epithelial cells had strong and diffuse positive expression of: AE1/3, CK7, CK5/6, p40, and p63. CK20, synaptophysin, and chromogranin expression was absent. Atypical epithelial cells showed patchy positive expression of p53. The ductal elements within the benign precursor had strong expression of CEA and EMA and retained a myoepithelial cell layer noted by positive expression of S100; with the transition to malignancy, loss of ductal elements were seen. Ki-67 immunostain demonstrated a markedly increased, but biphasic, proliferative index with the banal area around 25-30% and the malignant areas approaching 90-95%. These findings supported a diagnosis of eccrine spiradenocarcinoma. Due to its rarity, there are no standardized treatment guidelines for ESC, however ESC has a poor prognosis due to affinity for local relapse and its metastatic potential. As adnexal carcinomas are non-distinct in their clinical presentation, this case highlights the histopathologic features which can aid in differentiation of eccrine spiradenocarcinoma.

Financial Disclosure:
No current or relevant financial relationships exist.

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Emily Williams, MD