Answer of Dermatopathology Case 38

Trichoblastoma

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Abstract:

Cytologic features of trichoblastoma in fine needle aspiration biopsies.Acta Cytol. 2009 Nov-Dec;53(6):679-82.
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 aspirationand allow a definitive diagnosis. STUDY DESIGN: A 58-year-old male presented witha 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 atrichoblastic fibroma, and a retrospective analysis of the cytology wasperformed. RESULTS: The cytologic features of trichoblastoma resembled a cellular fibroadenoma/phyllodes tumor on aspiration, not previously described in theliterature. 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 cellsheets 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 featureswere 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.

Bcl-2 and CD10 expression in the differential diagnosis of trichoblastoma, basal cell carcinoma, and basal cell carcinoma with follicular differentiation. Int J Dermatol. 2009 Jul;48(7):713-7.
BACKGROUND: Both trichoblastoma and basal cell carcinoma (BCC) of the skin are characterized morphologically by the proliferation of basaloid cells; however,BCCs are clinically associated with a more aggressive behavior. An accurate diagnosis of these lesions is essential for effective, timely treatment and appropriate therapeutic decisions. METHODS: This study includes 40 lesions. Bcl-2and CD10 immunohistochemistry were performed in all cases and the patterns ofexpression were analyzed. RESULTS: Bcl-2 is useful for the detection of BCC with diffuse expression in nests of basaloid cells, but cannot distinguish between BCC with follicular differentiation and trichoblastoma, as both lesions show the samepattern with positive and negative areas. Conversely, CD10 expression can distinguish between trichoblastomas with peritumoral stromal staining and BCCswith epithelial staining. If both stromal and epithelial areas are stained, thesecases are classified as BCC with follicular differentiation. CONCLUSIONS: CD10 is useful for distinguishing between BCC with widespread follicular differentiation and trichoblastomas.