Bilateral maxillary sinus hypoplasia and aplasia: radiological and clinical findings.

Maxillary sinus hypoplasia (MSH) is classified into three types depending upon embryological development of the sinus and uncinate process. Type III MSH is characterized by a near-absence of the uncinate process and an almost absent cleft-like sinus. Bilateral maxillary sinus aplasia or severe hypoplasia with associated paranasal sinus abnormalities is extremely rare. Two cases with severe maxillary sinus hypoplasia/aplasia (one of them with other associated paranasal sinus abnormalities) are presented in this article. This extremely rare abnormality should be kept in mind to prevent misdiagnosis and possible complications during endoscopic sinus surgery.