Malignant Eccrine Spiradenoma: A Case Report and Review of the Literature

BACKGROUND: Eccrine spiradenoma is a well-differentiated benign tumor of the sweat glands. Malignant change arising within eccrine spiradenoma is rare. OBJECTIVE: We describe a patient with malignant eccrine spiradenoma exhibiting both carcinomatous and sarcomatous differentiation. METHODS: Case report and literature review. RESULTS: A 37-year-old woman noted enlargement of a left axillary tumor that had been present for 20 years. The tumor was resected and the specimen, measuring 3.0 cm x 1.5 cm, revealed an encapsulated benign eccrine spiradenoma as well as an undifferentiated carcinoma possessing both carcinomatous and sarcomatous components. A transition zone was evident between the benign eccrine spiradenoma and the undifferentiated carcinoma, suggesting that the latter had arisen from the benign tumor. The malignant areas consisted principally of undifferentiated carcinoma (70%), although squamous cell carcinoma (10%), adenocarcinoma (10%), and chondrosarcomatous (10%) components were also present. Numerous mitotic figures were noted within the areas of malignant change, suggesting that the tumor was aggressive in nature. The patient died of systemic metastases 7 months after diagnosis. CONCLUSION: Although eccrine spiradenomas are usually benign, they can, on rare occasions, undergo malignant transformation. This case report describes one such occurrence of malignant transformation of a benign eccrine spiradenoma that unfortunately resulted in the patient's death from systemic metastases 7 months after diagnosis.