Histological Features Of Low-Grade Spiradenocarcinoma: A Case Report.

Summary: Spiradenocarcinoma is a rare malignant skin adnexal neoplasm. It is histologically classified into low-grade and high-grade tumors. Low-grade carcinomas are extremely rare with only a few reported cases and have a more favourable clinical outcome. We present a case of low-grade spiradenocarcinoma in a 71-year-old male who presented with a slowly growing, solitary painless mass in right arm for the past 2 years. Histological examination revealed well-circumscribed tumor nodules arranged in gland like nests and sheets present in deep dermis with focal areas of infiltration into subcutis along with transition between the benign component. Moderate nuclear atypia with increased atypical mitotic figures, loss of dual population pattern along with areas of necrosis, dilated vessels, and foci of squamatization were also found in our case. Immunohistochemistry revealed positivity of S-100 and stained negative for CEA, synaptophysin and chromogranin. Pathologists must be familiar with the diverse features on histology to identify the malignant transformation in benign spiradenomas for the correct diagnosis of this rare neoplasm.