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Table 2 Differential diagnosis for trichogerminoma in histological and immunohistochemical characteristics

From: Trichogerminoma, a rare cutaneous follicular neoplasm with indolent clinical course: report of two cases and review of literature

Characteristics Trichogerminoma Trichoblastoma Trichoepithelioma Basal cell carcinoma with follicular differentiation Trichilemmoma
Basic histological features Circumscribed lobules made up of basaloid cells with peripheral palisading, no epidermal connection, no retraction space Large basaloid epithelial lobules, no epidermal connection, no retraction cleft Mutiple lobules and nests of basaloid cells, confined to superficila dermis, no retraction cleft Irregular lobues made up of basaloid cells with prominent peripheral palisading, with epidermis attachment and retracion space Irregular lobues, with epidermis and follicles attachment
Specific characteristics Centrolobular cell balls, papillary mesenchymal bodies(++), follicular cyst(+/−), Papillary mesenchymal bodies(++), follicular cyst(+/−) Papillary mesenchymal bodies(+), horn cyst(++) Mitotic and apoptotic bodies(+), follicular cyst(+/−), papillary mesenchymal bodies(−) Thickened, eosinophilic basement membrane surrounding tumor lobules
Immunohistochemistry “Zonal” CK5/6, P63 and Bcl-2 immunostaining, CK20+ Merker cells in lobules “Zonal” Bcl-2 immunostaining, CK20+ Merker cells in lobules Androgen receptor -, CK20+ (in some reports) Bcl-2 diffusely(+), No CK20+ Merker cells in tumor lobules PAS + clear cells