Low grade malignant eccrinespiradenoma with florid squamous differentiation: A Potential Diagnostic Pitfall

Malignant eccrinespiradenomas (MES) are rare, fatal neoplasmsand typically manifest as rapid enlargement of long-standing benign eccrinespiradenomas. Low grade malignancyarising in benign eccrinespiradenomas are difficult to diagnose as the morphological changes are subtle and needs careful examination by the pathologist. MES frequently shows focal squamous differentiation, which may be florid in rare instances. We herein report a case of low grade malignancy in an eccrinespiradenoma with florid squamous differentiation. The present tumor was removed twomonths after rapid increase in size of a long standing nodule over the left forearm was noted by the patient. Histopathological examination showed the earliest stage of malignant transformation within eccrinespiradenoma. The early changes of malignant transformation was characterized by nuclear pleomorphism, loss of two cell types, increased mitotic activity with atypical mitoses, partial loss of PAS positive basement membrane material and florid squamous differentiation. Immunostaining for p53 revealed absent staining in benign areas and increased expression in malignant areas. Ki 67 score was less than 1% in benign areas and was increased (4-5%) in the malignant area. Since patient had tumor free margin, no palpable lymph node in the axilla or evidence ofdistant metastasis, he was not put on any adjuvant therapy. Such cases must be followed up carefully. In conclusion, we need more information about low grade malignant eccrinespiradenoma, its biological behavior, and treatment modalities.