Diffuse pulmonary meningotheliomatosis
Diffuse pulmonary meningotheliomatosis is a rare condition manifested by multiple minute pulmonary meningothelial nodules (MPMNs) scattered throughout the lungs.
Epidemiology
There may be an increased female predilection and they tend to peak around the 5to 7decades of life at the time of detection.
Clinical presentation
These nodules are generally asymptomatic and are usually found incidentally at autopsy or in surgical specimens resected for unrelated causes. Some patients may have clinical symptoms such as dyspnea and shortness of breath.
Pathology
They are minute pulmonary meningothelial nodules histologically composed of small nests of epithelioid cells located within the lung interstitium.
Some MPMNs show monoclonal expansion, whereas others can be polyclonal, which generally suggest that MPMNs are reactive rather than being neoplastic.
Immunohistochemistry
Can show positivity for:
- epithelial membrane antigen
- vimentin
Negative staining for:
- cytokeratin
- actin
- S-100 protein
- CD34
- chromogranin
- synaptophysin
Radiographic features
CT
They may be seen as diffuse micronodules (with the sizes ranging of around 100 µm and 11 mm ) similar to a miliary pattern seen in miliary tuberculosis or miliary metastases but can also present as small ground glass nodular opacities. Cavitation is rarely reported .
Treatment and prognosis
At the initial time of initial writing (early 2018), they are generally considered benign. Some authors have shown isolated MPMN lacking mutational damage, consistent with a reactive origin with some suggestion of MPMN-omatosis syndrome representing the transition between a reactive and neoplastic proliferation .
History and etymology
Minute pulmonary meningothelial‐like nodules (MPMNs) were first described by Korn et al. in 1960 .
Differential diagnosis
If a miliary pattern is seen in the lungs, refer to miliary opacities.
See also
