Recurrent adenoid cystic carcinoma of paranasal sinuses: A rare case report.

Adenoid cystic carcinoma (ACC) is a distinct salivary gland neoplasm that predominantly occurs in the minor salivary gland. ACC is an uncommon tumor that progress slowly affecting 5% of paranasal sinuses with high distant metastasis rate in advance stages. This salivary gland tumor is difficult to diagnose both clinically and histopathologically due to its indolent presentation and diverse histopathological patterns. Hence, immunohistochemistry plays a decisive role in diagnosing this tumor. A recurrent case of ACC of paranasal sinuses in the maxillary sinus of a 41-year-old female patient without any extraoral abnormality is reported.