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Pseudomesotheliomatous adenocarcinoma: a reappraisal
1Department of Pulmonary and Mediastinal Pathology, Armed Forces Institute of Pathology, Washington, DC 20306-6000.
Abstract:
Adenocarcinomas of or in lung that clinically and pathologically mimic diffuse pleural mesotheliomas are rare. We reviewed selected clinical and pathologic features of 15 autopsy/surgical cases previously reported in the medical literature and of 15 additional cases from the files of the Armed Forces Institute of Pathology (AFIP). Ninety percent of the patients were men. The median age was 61 years. Sixty-three percent of the patients smoked, 17% of them had possible or definite occupational exposure to asbestos, and one patient had microscopically proven asbestosis. Most patients had chest pain, shortness of breath, or cough, and had unilateral pleural effusion in the chest x-ray. At thoracotomy or at autopsy, numerous nodules, plaques, or a continuous rind of tumor was present over the pleural surface. Microscopically, the tumors showed simplified glands, nests, cords, papillary, tubulopapillary or biphasic patterns of growth. The neoplasms contained mucin that stained with diastase-predigested periodic acid-Schiff (PAS), mucicarmine, and alcian blue (with or without hyaluronidase predigestion). All patients died with/of tumor, with a mean survival of 4.7 months for those reported in the medical literature and of 7 months for those in the AFIP files. These adenocarcinomas therefore mimic pleural mesothelioma not only in their clinical and gross and microscopic appearance, but also in their prognosis.
Insights
Rare lung adenocarcinomas mimic diffuse pleural mesotheliomas clinically and pathologically. These tumors present similarly to mesothelioma, affecting mostly men and leading to poor prognoses, highlighting diagnostic challenges.
Area of Science:
- Oncology
- Pathology
- Pulmonology
Background:
- Diffuse pleural mesotheliomas are rare but aggressive cancers.
- Certain lung adenocarcinomas can present with features mimicking mesothelioma.
- Accurate differentiation is crucial for appropriate patient management and prognosis.
Purpose of the Study:
- To investigate the clinical and pathological features of lung adenocarcinomas that mimic diffuse pleural mesotheliomas.
- To compare these features with those of actual pleural mesotheliomas.
- To understand the diagnostic challenges and prognostic implications.
Main Methods:
- Review of 30 cases (15 literature, 15 Armed Forces Institute of Pathology).
- Analysis of clinical presentation, radiological findings, gross pathology, and microscopic features.
- Histochemical staining for mucin was performed.
Main Results:
- 90% of patients were male, median age 61.
- Common symptoms included chest pain, shortness of breath, and cough with unilateral pleural effusion.
- Grossly, tumors appeared as nodules, plaques, or a rind over the pleura; microscopically, they showed glandular patterns and stained positive for mucin.
- Prognosis was poor, with mean survival of 4.7-7 months.
Conclusions:
- Lung adenocarcinomas can closely mimic pleural mesothelioma in clinical presentation, gross appearance, and microscopic features.
- The presence of mucin is a key differentiating factor.
- These tumors share a similar poor prognosis with pleural mesothelioma, underscoring the need for careful pathological examination.