Fine-needle aspiration biopsy as an adjunct to the diagnosis of a rare adnexal tumor of hair follicle origin: trichoblastoma.

Fine-needle aspiration biopsy (FNAB) is a technique used increasingly for the investigation of primary and metastatic cutaneous tumors. Trichoblastoma is a rare benign skin appendage tumor of hair germ origin. We report the diagnosis by FNAB of a rare giant subcutaneous tumor, trichoblastoma, from an 81-yr-old woman with a subcutaneous mass in the interscapular area of her back. The cytologic characteristics of the tumor are discussed in detail in this report. The findings have been compared with the histologic features of the tumor after surgical excision. We have characterized several distinctive cytologic features that may aid in the diagnosis of this rare neoplasm. While most reported cases have been diagnosed from surgical excisional biopsy specimens, FNAB may also be a valuable tool for the accurate diagnosis of trichoblastoma in the proper clinical context. Copyright 2003 Wiley-Liss, Inc.