Cytologic features of trichoblastoma in fine needle aspiration biopsies.

OBJECTIVE

To review the cytologic features of trichoblastoma in order to define criteria that may aid in identification of these tumors at the time of aspiration and allow a definitive diagnosis.

STUDY DESIGN

A 58-year-old male presented with a mass lesion on the thigh. On fine needle aspiration, the patient was diagnosed as having a benign skin adnexal tumor. Histology showed the presence of a trichoblastic fibroma, and a retrospective analysis of the cytology was performed.

RESULTS

The cytologic features of trichoblastoma resembled a cellular fibroadenoma/phyllodes tumor on aspiration, not previously described in the literature. If the cytomorphology of a skin or subcutaneous aspirate appears to resemble that of a fibroadenoma, the diagnosis of a trichoblastoma should be entertained. Peripheral palisading of nuclei at the edges of the basaloid cell sheets and squamous eddy formation are clues to the diagnosis but may be very focal and could be overlooked. If the tumor occurs in the region of the breast, distinction from a fibroadenoma would be difficult if these additional features were not prominent.

CONCLUSION

Knowledge of the cytologic features of trichoblastoma will allow correct management of the patient and prevent misdiagnosis as other benign or malignant tumors.