Perianal Plasmablastic Lymphoma Masquerading as a Buschke-Löwenstein-like Tumour in an HIV-infected Patient with Recurrent Anal Condyloma

Plasmablastic lymphoma (PBL) commonly presents as a primary (de novo) oral or extraoral mucocutaneous or nodal mass lesion in patients with HIV/AIDS. PBL developing as a secondary malignancy at the same location as a pre-existing tumour is extremely rare and has never been reported in association with longstanding or recurrent anal condyloma. A Buschke-Löwenstein tumour is a rare gigantic, locally destructive condyloma that is usually located in the anogenital region. We report a case of a diagnostically and therapeutically challenging PBL that presented as a rapidly enlarging mass underlying a giant condyloma, thereby mimicking a benign Buschke-Löwenstein tumour. Clinical suspicion was further masked by the co-presence of fistulae in ano and adjacent abscess pockets at the time of diagnosis. By the time of final diagnosis, the lymphoma had disseminated to regional lymph nodes, a month later to pleural cavities and 4 months later to the leptomeninges and bilateral kidneys, leading to permanent deferral of chemotherapeutic intervention. LEARNING POINTS: Plasmablastic lymphoma presenting as a secondary tumour in a patient with pre-existing giant anal condyloma has not been reported previously in the literature. Unusual clinical presentation of a recurrent giant condyloma, especially rapid growth and significant change in physical appearance, should kindle a high index of suspicion for a secondary aggressive tumour. Plasmablastic lymphoma disseminates early and rapidly, which complicates its response to treatment.