Malignant transformation of eccrine spiradenoma is extremely rare. We describe the case of a 70-year-old man with malignant eccrine spiradenoma of the forearm and metastases to the axillary lymph nodes. Surgical excision with adequate margins and lymph node dissection was performed. Tamoxifen therapy was instituted after obtaining positive immunostaining results for estrogen receptor. After 41 months of follow-up, there has been no recurrence or distant metastases. Wide local excision and close follow-up are crucial in the management of malignant eccrine spiradenoma. The role of other therapeutic modalities, including hormonal therapy, remains to be determined.