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diffuse intrapulmonary malignant mesothelioma

Wednesday 26 June 2013

Malignant mesothelioma typically encases lungs as a thick rind, while relatively sparing lung parenchyma. An unusual presentation of mesothelioma has been described, characterized by diffuse intrapulmonary growth, with absent or inconspicuous pleural involvement, clinically simulating interstitial lung disease (ILD).

"Diffuse intrapulmonary malignant mesothelioma" is a rare variant with a distinctive presentation that clinically mimics ILD.

Recognition is essential to avoid misdiagnosis.

Histologic evaluation reveals a neoplastic proliferation of bland epithelioid or spindled cells, showing various growth patterns simulating silicotic nodules, desquamative interstitial pneumonia, organizing pneumonia, and Langerhans cell histiocytosis.

Some areas mimick adenocarcinoma, with lepidic, acinar, micropapillary, and solid patterns.

Initial diagnoses by referring pathologists included reactive changes:
- hypersensitivity pneumonitis versus drug reaction
- desquamative interstitial pneumonia versus neoplasm
mesothelioma

Microscopic pleural involvement can be identified.

Reference

- Diffuse Intrapulmonary Malignant Mesothelioma Masquerading as Interstitial Lung Disease: A Distinctive Variant of Mesothelioma. Larsen BT, Klein JR, Hornychov√° H, Nuti R, Thirumala S, Leslie KO, Colby TV, Tazelaar HD. Am J Surg Pathol. 2013 Jun 20. PMID: 23797722