Invasive squamous cell carcinoma arising in an inverted papilloma involving oral cavity.

Inverted papilloma (IP) is a benign tumour characterized by the growth of epithelial cells downward into the underlying supportive tissue. The tumour derives from the lining mucosa of the nasal cavity and paranasal sinuses. IP typically arises as a unilateral lesion from the lateral wall of the nasal cavity and extends secondarily to the paranasal sinuses. The aggressive behaviour of IP causing local invasion, its tendency for local recurrence, and its propensity to be associated with carcinoma constitute serious complications. This paper describes a very rare case of IP associated with squamous cell carcinoma, extending into paranasal sinuses, causing destruction of the bony wall of maxillary sinus and involvement of the oral cavity.