Giant Epidermoid Cyst of the Maxillary Sinus: A Postoperative Complication?

Epidermoid cysts are benign lesions, which are usually detected on the floor of the mouth in the head and neck region. They can develop from abnormal epithelial components of an ectoderm tissue during the embryological life or alternatively they can arise from the implanted epithelium after trauma or surgery. The diagnosis of an epidermoid cyst in the maxillary sinus can be challenging and it could be easily mistaken for any benign or malign lesion of the nasal cavity and paranasal sinuses. In this case, we present a 44-year-old man with a giant epidermoid cyst in the right maxillary sinus with a previous history of paranasal sinus surgery. We present a very rare case of epidermoid cyst and also discuss the importance of radiological imaging modalities in differential diagnosis of a unilateral expansile mass in the maxillary sinus.