Low-grade malignant eccrine spiradenoma with systemic metastases.

Malignant eccrine spiradenoma (MES) is a very rare tumor. Tumors can be low grade or high grade. There are nine cases in the literature with systemic metastases. Of these, only one was low grade; the others had obvious features of high-grade malignancy such as pleomorphism, increased mitoses, and abnormal mitoses. Low grade MESs are more difficult to diagnose and are said to have a better prognosis. We report an additional case of low-grade MES with systemic metastases. It had a monotonous appearance with few mitotic figures and minimal pleomorphism. Vascular invasion was seen in both cases of low-grade MES and may be an important prognostic feature.