Squamous cell carcinoma associated with intralesional injection of cidofovir for recurrent respiratory papillomatosis

Recurrent respiratory papillomatosis is a common neoplasm of the larynx that may lead to severe, recurrent lesions. Intralesional injection of cidofovir has shown promise as an adjuvant therapy. There is concern for possible malignant transformation with its use but, to our knowledge, this has not been documented in the literature. We report a case of invasive squamous cell cancer arising from squamous papilloma in a patient treated with multiple injections of cidofovir. Although causation is not shown, we believe the association presented is a valuable addition to the literature and an important consideration in the use of cidofovir.