From Spiradenocarcinoma to Spiradenoma: A Case of Histopathological Diagnostic Reclassification

Spiradenocarcinoma is a rare malignant cutaneous adnexal neoplasm that may arise from a preexisting spiradenoma. Distinguishing benign from malignant lesions can be challenging, and diagnostic classification has important implications for treatment and follow-up. A 37-year-old woman presented with an approximately 3-cm erythematous-violaceous nodule on the right ankle that had been present for five years and had recently grown rapidly. The initial histopathological assessment described a malignant epithelial neoplasm compatible with spiradenocarcinoma associated with a benign spiradenoma component. The patient underwent wider surgical re-excision with clinical margins exceeding 1 cm, and computed tomography of the chest, abdomen, and pelvis showed no metastatic disease. No residual neoplasm was identified in the re-excision specimen. Subsequent review of the original histological slides at a second laboratory identified a well-circumscribed, lobulated, solid-cystic dermal lesion with two distinct epithelial cell populations and an interspersed lymphocytic infiltrate, without infiltrative growth, nuclear atypia, mitotic activity, or necrosis in the reviewed material. The diagnosis was revised to benign spiradenoma. Immunohistochemistry supported the diagnosis of an eccrine neoplasm. This case illustrates the diagnostic challenges in distinguishing spiradenoma from spiradenocarcinoma and the clinical implications of discrepant histopathological assessments. Morphological evaluation remains central to classification, while immunohistochemistry provides complementary information.