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Table 2 Differential diagnosis for trichogerminoma in histological and immunohistochemical characteristics
| 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 |
