Poroid hidradenoma. Report of a case with cytologic findings on fine needle aspiration.Acta Cytol. 1999 May-Jun;43(3):471-4.

BACKGROUND: Fine needle aspiration cytology (FNAC) can be used for establishing a diagnosis of cutaneous lesions, especially in cases with cyst formation. Poroid hidradenoma is eccrine neoplasm with both solid and cystic components. CASE: A 77-year-old female presented with a slightly elevated nodule in the skin on her left elbow. The tumor was well demarcated, 2.7 x 2.4 cm and soft, and overlying skin was slightly reddish. FNAC revealed two types of cell: one had abundant cytoplasm in which small to large, occasionally multinucleated nuclei with small but distinct nucleoli were evident. Chromatin was finely granular, and nuclear membrane was thin and almost smooth. Another type of cell had scanty cytoplasm and a round to oval nucleus with small but prominent nucleoli. Histologic diagnosis was poroid hidradenoma. CONCLUSION: FNAC can be useful for diagnosing intradermal cystic lesions before surgical resection.

Poroid hidradenoma. A case presentation.J Am Podiatr Med Assoc. 1998 Oct;88(10):510-3.

Poroid hidradenoma is a benign soft-tissue neoplasm with eccrine differentiation. It is the newest addition to a group of neoplasms known as poromas. Although it becomes malignant in less than 1% of cases, its histologic characteristics may resemble those of malignant neoplasms; thus it is easily misdiagnosed. Twenty-one percent of poroid hidradenomas occur in the extremities. The histologic and clinical features of this tumor are presented here, along with a case report.