Pneumosinus dilatans, an uncommon clinical condition: A case report.

Pneumosinus dilatans (PSD) is an abnormal expansion of the paranasal sinus beyond the normal anatomical boundaries of the sinus and the associated bone, with normal thickness of the sinus wall. It is a rare clinical condition, with a relatively small number of cases documented in the literature. Numerous theories have been proposed to explain the etiology of PSD, of which only the ball valve mechanism and Genetic predisposition with hormonal trigger have some scientific evidence. Usually detected incidentally by imaging, however, it may present with symptoms such as swelling of the forehead (with involvement of the frontal sinus), headache, nasal block, and symptoms related to mass effect on adjacent structures. Imaging plays a major role in diagnosis, differential diagnosis, and identification of associated conditions, which is described in detail in this case report. The differential diagnosis includes hypersinus, pneumosinus, mucolcele, and benign sinus tumors. Conservative management by endoscopy is considered in asymptomatic patients, and surgical management is considered in patients with aesthetic concerns. We present a case of PSD in a 35-year-old female patient who presented with right-sided nasal obstruction and intermittent dull, nonradiating frontal headache for 3 years.