Malignant eccrine spiradenoma is an exceedingly rare tumor of cutaneous adenxal origin. It usually arises from a pre-existing
eccrine spiradenoma and typically manifest as rapid enlargement in long-standing spiradenomas. It has two distinct
patterns; high-grade carcinoma and low-grade tumor imitating benign spiradenoma. Low grade MES have subtle microscopic
features, that are more difficult to diagnose and are said to have a better prognosis. MES frequently shows focal squamous
differentiation, which may be florid in rare instances. We describe the diagnostic difficulties encountered in a case of low grade
malignancy in a eccrine spiradenoma with florid squamous differentiation .The tumor was removed 2 months 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 eccrine spiradenoma ,characterized by mild nuclear pleomorphism, loss of two cell
types, increased mitotic activity with atypical mitoses and florid squamous differentiation. PAS stain outlined a partial loss or
destruction of PAS positive basement membrane in the malignant area. There was no evidence of vascular invasion. P53 was not
expressed in benign areas, whilst in malignant areas occasional nuclear reaction was noted.
The motive behind presenting this case is to highlight importance of recognizing some of the histological features of early
malignant transformation in a rapidly increasing eccrine spiradenoma and diagnostic difficulties that can arise due to florid
squamous differentiation in these tumors.
Dr Kavita Mardi has MD in Pathology from Indira Gandhi Medical College, Shimla. She has also acquired DNB (Diplomate of National Board) degree in Pathology from National Board of Examinations, New delhi. She has 11 years of post PG teaching experience and presently working as Associate Professor in Pathology at Indira Gandhi Medical College, Shimla. She has published more than 75 papers in reputed national and international journals and reviewed articles for a number of reputed journals.
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