However, trichoblastoma stains positive for stromal cluster of differentiation (CD) antigen 10 and CD antigen 34 as well as pleckstrin homology-like domain family A member 1 (PHLDA1), a follicular stem cell marker, whereas the basal cell carcinoma does not (Table 2) [36,42]. Nevertheless, the differentiation of an adnexal tumor from basal cell carcinoma using immunohistochemistry is somewhat controversial and is rarely performed in daily dermatopathology practice. The gene discussed is PHLDA1; the disease is trichoblastoma.