# Mass effect of a large frontal pneumosinus dilatans on the left frontal lobe: a case report and literature review

## TL;DR

A rare case of a large frontal pneumosinus dilatans causing a mass effect on the brain is reported, highlighting the importance of multidisciplinary evaluation.

## Contribution

This case report highlights the rare association between pneumosinus dilatans and Dyke–Davidoff Masson syndrome.

## Key findings

- MRI revealed marked dilatation of the left frontal sinus with a mass effect on the left frontal lobe.
- The patient was diagnosed with Dyke–Davidoff Masson syndrome after multidisciplinary review.
- Conservative management resulted in the patient remaining stable over time.

## Abstract

Pneumosinus dilatans (PD) is a rare condition characterized by abnormal expansion of the paranasal sinus without bone destruction or significant mucosal disease. Its association with Dyke–Davidoff Masson syndrome (DDMS) is particularly uncommon. We report the case of a 54-year-old female with learning disabilities, pseudoseizures, and asthma who was referred to our clinic after an MRI performed for decreased visual acuity revealed marked dilatation of the large left frontal sinus. She denied nasal symptoms but reported frontal headaches. Endoscopic examination was unremarkable. Imaging demonstrated progressive sinus enlargement and a mass effect in the left frontal lobe. The case was reviewed in a multidisciplinary setting and diagnosed as DDMS. Despite the conservative management, the patient remained stable. This case underscores the importance of recognizing PD and its rare associations, and emphasizes the value of multidisciplinary evaluation and radiological surveillance in selected patients.