Diffuse Pulmonary Meningotheliomatosis: An Exceedingly Rare Disease for a Not-So-Rare Pattern.

Diffuse pulmonary meningotheliomatosis (DPM) is a rare lung disease characterized by the proliferation of meningothelial-like cells within the pulmonary interstitium. It predominantly affects middle-aged women and is often asymptomatic, although mild respiratory symptoms may occur. Chest CT typically shows diffuse and bilateral micronodules, and histology confirms meningothelial-like nodules expressing epithelial membrane antigen (EMA), CD56, and progesterone receptor. We report the case of a 72-year-old woman undergoing breast cancer staging, who was incidentally found to have bilateral pulmonary micronodules. A conventional transbronchial biopsy confirmed DPM, and a brain MRI ruled out meningioma. The patient remains stable without treatment. DPM is often misdiagnosed, with metastatic disease and granulomatous conditions as key differentials. Although biopsy aids diagnosis, correlation with imaging findings is essential. No specific treatment is required, and the prognosis is generally favorable. Further research is needed to refine diagnoses and management strategies.