An exceptional perianal basal cell carcinoma with follicular differentiation mimicking Hemorrhoids: a rare case report

Abstract Perianal basal cell carcinoma (BCC) is a rare malignancy seldom encountered in clinical practice. It can clinically mimic benign anorectal conditions such as hemorrhoids or cysts, leading to diagnostic delay. We report the case of a 62-year-old Moroccan man presenting with a slowly enlarging perianal mass over four years, initially presumed to be hemorrhoidal. Histopathological analysis confirmed a diagnosis of BCC with follicular differentiation. Immunohistochemistry was positive for P63, CK5/6, and BCL2, and negative for melanocytic markers. Magnetic resonance imaging (MRI) showed no local invasion or distant metastasis. Wide local excision with tumor-free margins was performed, and the multidisciplinary team recommended surveillance. This case highlights the diagnostic challenge of perianal BCC mimicking benign lesions and emphasizes the need for histopathological confirmation. Follicular differentiation is exceptionally uncommon and should be distinguished from adnexal tumors such as trichoblastic carcinoma.