Incidence of Diffuse Pulmonary Meningotheliomatosis
Diffuse pulmonary meningotheliomatosis (DPM) is an exceedingly rare entity with fewer than 15 documented cases in the medical literature as of 2020. 1
Epidemiology and Clinical Characteristics
DPM is characterized by the presence of widespread bilateral minute pulmonary meningothelial-like nodules (MPMNs) throughout the lungs. Based on the available evidence:
- Strong female predominance (10 women out of 11 documented cases) 2
- Age range: 51-75 years with mean age of 64±8 years 2
- Most patients (8 out of 11) had no history of smoking or occupational exposure 2
Clinical Presentation
Patients with DPM may present with:
- Dyspnea, shortness of breath, or fatigue (7 out of 11 cases) 2
- Non-exertional chest pressure and dry cough 1
- Mild abnormalities on pulmonary function tests (8 out of 11 cases) 2
- Some patients are completely asymptomatic with incidental findings on imaging 1, 3
Radiological Features
On imaging, DPM presents as:
- Diffuse bilateral small solid or ground-glass nodules <5mm in diameter 2
- Random distribution throughout both lungs 2, 3
- Occasional cavitation of nodules 2
- Can mimic metastatic disease, interstitial lung disease, or lymphangitis carcinomatosa 3
Diagnosis
Diagnosis of DPM requires:
- High-resolution CT showing innumerable diffuse small ground-glass nodules 1
- Histological confirmation via:
Pathological Features
Histologically, DPM is characterized by:
- Small clusters of epithelioid cells with round to oval nuclei without atypia 3
- Whorled/nested clusters of elongated cells with oval nuclei 4
- Immunohistochemical positivity for epithelial membrane antigen and vimentin 3
- Negative staining for cytokeratin, actin, S-100 protein, CD34, chromogranin, and synaptophysin 3
Clinical Course and Management
The natural history of DPM appears to be benign:
- Follow-up data available for 3 patients showed stable lung lesions over 12-92 months 2
- No specific treatment is required for asymptomatic patients 1, 2
- Management focuses on monitoring and symptomatic treatment
Differential Diagnosis
DPM should be differentiated from:
- Metastatic disease 3, 5
- Idiopathic interstitial pneumonia 3
- Lymphangitis carcinomatosa 3
- Other causes of diffuse cystic lung diseases such as lymphangioleiomyomatosis 6
Research Limitations
It's important to note that:
- The extreme rarity of this condition limits comprehensive epidemiological data
- Most information comes from case reports and small case series
- Long-term follow-up data is limited to only a few cases
- The etiology and pathogenesis remain poorly understood