CLINICOPATHOLOGIC AND MOLECULAR CHARACTERIZATION OF A SERIES OF SPORADIC TRICHOBLASTIC NEOPLASMS

Summary: Herein, we report the histopathologic features of 15 cases of sporadic trichoblastic neoplasms. Among cases with gene expression prole, all tumors demonstrated consistent mutation signature associated with DNA repair defect and a case of trichogerminoma with FOXK1::GRHL1 fusion. The absence of UV mutation signature or PTCH1 mutation indicates distinct molecular etiology than basal cell carcinoma which is the main histological differential diagnosis of trichoblastoma. These fIndings shed light on molecular tumorigenesis which could potentially be of use for diagnostic practice. Larger scale validation studies are needed.