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

## TL;DR

A rare case of perianal basal cell carcinoma was mistaken for hemorrhoids, highlighting the need for accurate diagnosis through histopathology.

## Contribution

This case report presents an exceptionally rare instance of perianal BCC with follicular differentiation.

## Key findings

- The tumor was initially misdiagnosed as hemorrhoids but was confirmed as BCC via histopathology.
- Immunohistochemistry showed positivity for P63, CK5/6, and BCL2, and negativity for melanocytic markers.
- MRI showed no local invasion or metastasis, and the patient underwent successful wide local excision.

## 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.