External auditory canal eccrine spiradenocarcinoma: A case report and review of the literature

Background. Eccrine spiradenocarcinoma is a rare dermal appendage carcinoma believed to arise from transformation of a long-standing benign spiradenoma. This tumor demonstrates highly malignant biologic behavior with a high recurrence rate, frequent lymph node metastases, and overall poor survival. Methods. We report the first case of eccrine spiradenocarcinoma arising in the external auditory canal. The management of this tumor, its histopathologic characteristics, and a review of literature are presented. Results. A literature review identified 17 cases of eccrine spiradenocarcinoma in the head and neck region. Local recurrence occurred in 58.8% of patients, with an average of 23 months from diagnosis. Lymph node metastasis occurred in 35.3%, with an average of 31 months from diagnosis. Other metastatic sites included skin, bone, and lung. Disease-specific mortality was 22.2%. Conclusions. Eccrine spiradenocarcinoma is an aggressive tumor with a poor prognosis. Primary treatment should include wide local excision with or without regional lymphadenectomy. Isolated successful treatments have been documented with adjuvant hormonal manipulation, chemotherapy, and radiation therapy.