Maxillary Pneumosinus Dilatans Presenting With Proptosis: A Case Report and Review of the Literature.

Background: Pneumosinus dilatans (PSD) is a rare pathological paranasal sinus expansion. This condition is usually symptomatic or cosmetically apparent, requiring surgical intervention. Multiple hypotheses have been postulated as to the cause of this condition; however, the precise cause and pathogenesis remain obscure.

Case report and Methods: An 11-year-old boy presented with right eye bulging and was subsequently found to have PSD of the maxillary sinus. A search was conducted of the PubMed electronic database, using the keywords "pneumosinus dilatans," "pneum(oco)ele," "pneum(oc)ele," "pneum(atoco)ele," and "air cyst." Articles published in English were reviewed.

Results: The literature review identified 29 cases of PSD involving the maxillary sinus. The mean age of presentation was 25 years old. Only the right maxillary sinus was affected in 16 cases, followed by the bilateral sinuses in 7 cases and the left sinus in 6 cases. In 5 cases, all paranasal sinuses, along with the maxillary sinus, were expanded. The most common presenting symptom was facial swelling, which was found in 55% of the cases, followed by proptosis and pain. Computed tomography is the gold standard radiological method for diagnosing PSD.

Conclusions: Pneumosinus dilatans is a rare condition that is usually symptomatic and requires surgical intervention. The etiology of the disease is attributed to multiple hypotheses, but more studies are needed to explore this condition further.