A rare malignancy: A case report of early progression of anal Buschke–Löwenstein tumor into squamous cell carcinoma in an immunocompetent patient

Introduction and importance Buschke-Löwenstein tumor (BLT) is a rare perianal lesion caused by low-risk mucosal HPV 6 or 11 but less frequently associated with high-risk HPV types. It is a large, exophytic, verrucous lesion of the anogenital region. BLT presents as a benign tumor but exhibits malignant clinical behavior and has a high rate of local recurrence and malignant transformation. The optimal treatment approach for BLT is still debated due to the lack of consensus. Various therapeutic modalities have been proposed, including topical agents, surgical excision, immunotherapy, chemo-radiotherapy, and electrocoagulation. Case presentation This case report presents a heterosexual, immunocompetent patient with anal pain, pruritus, and spontaneous bleeding. The physical examination revealed an exophytic, pedunculated verrucous lesion, which appeared to be a typical fibroepithelial lesion. Clinical discussion The patient underwent wide excision, followed by a re-excision due to a surgical margin issue. The tumor exhibited malignant transformation into a well-differentiated SCC. However, due to the tumor's stage, size, location, histological type, and the extended time interval between the two surgeries, postoperative radiotherapy was not performed. Follow-up examinations over 12 months revealed no evidence of recurrence in either the patient's clinical evaluation or pelvic MRI. Conclusions Although comprehensive research is lacking, wide local excision is considered the preferred first-line treatment for early-stage cases without evidence of local invasion. Furthermore, HPV immunization can prevent the development of Buschke-Löwenstein tumor, and early administration of the HPV vaccine is recommended to avoid acquiring HPV infection.