Diffuse intrapulmonary mesothelioma mimicking pulmonary lepidic adenocarcinoma: a rare case report and review of the literature

Our plain-English summary of Diffuse intrapulmonary mesothelioma mimicking pulmonary lepidic adenocarcinoma: a rare case report and review of the literature, by W. RanYue, W. ChunYan, H. Likun, et al (Diagnostic Pathology, 2023).

The study

• Authors: W. RanYue, W. ChunYan, H. Likun, Z. LiPing, L. JieLu, D. ZhengWei
• Journal: Diagnostic Pathology
• Published: 2023;18(1):64
• Type of article: Review, Case report
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Mesothelioma, with various clinical manifestations, radiological features, and histomorphological types, can be divided into epithelioid, sarcomatoid, and biphasic types, according to their histomorphological characteristics. There is a rare growth pattern of pleural mesothelioma: diffuse intrapulmonary mesothelioma (DIM), with a distinctive pattern of predominantly intrapulmonary growth, has no or minimal pleural involvement, and simulates interstitial lung disease(ILD) clinically and radiologically. A 59-year-old man presented to the hospital with recurrent pleural effusions for 4 years and a history of asbestos exposure. Computed tomography (CT) showed bilateral pure ground-glass opacity lesions, and the tumor cells showed a lepidic growth pattern pathologically. Immunohistochemical staining was positive for CK, WT-1, calretinin, D2-40, CK5/6, and Claudin4, while TTF-1, CEA, EMA, CK7, CK20, and other epithelial markers were negative. BAP1 loss its expression, and MTAP was positive in cytoplasm. CDKN2A was negative tested by Fluorescence in situ hybridization (FISH). The final diagnosis was DIM. In conclusion, we should recognize this rare disease to avoid misdiagnosis and delayed treatment.

© 2023. The Author(s).

In plain English

This article reported a single patient with diffuse intrapulmonary mesothelioma (DIM) and reviewed earlier published cases. The authors describe DIM as a rare growth pattern of pleural mesothelioma that grows mainly inside the lung. The patient was a 59-year-old man with fluid around the right lung (recurrent pleural effusion) for 4 years. He had worked on high-temperature stoves for more than 10 years and had daily exposure to asbestos-containing thermal insulation materials. The article does not name a fiber type. CT showed ground-glass lesions in both lungs. Under the microscope, the tumor grew along the walls of the air sacs (a lepidic pattern), resembling lung adenocarcinoma. Stains were positive for mesothelial markers and showed loss of BAP1. No asbestos bodies were seen. After surgery and immunotherapy, he lost 20 kg in 9 months. Across 17 cases (16 published plus this one), 15 were male and 6 had a history of asbestos exposure. The authors reported a median survival of five months for DIM. The authors concluded that awareness of this rare disease is essential to avoid misdiagnosis.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Case report of one patient, with a review of previously published case reports of DIM
• Who was studied: One 59-year-old man treated at Shanghai Pulmonary Hospital, China, with recurrent pleural effusion for 4 years. The review covered 17 DIM cases: 16 previously reported in English plus this case.
• Exposure: More than 10 years of work on high-temperature stoves with daily exposure to asbestos-containing thermal insulation materials. No fiber type or dose is given.
• Main results:
  • In the patient, CT showed ground-glass lesions in both lungs. The larger lesion was in the right lower lobe, 35 mm long.
  • In the patient, the tumor grew mainly along the alveolar walls (lepidic pattern).
  • In the patient, the tumor cells were positive for CK, Claudin4 and the mesothelial markers WT-1, calretinin, D2-40 and CK5/6.
  • In the patient, BAP1 expression was lost and MTAP was expressed. FISH showed a normal CDKN2A pattern with no homozygous deletion.
  • No asbestos bodies were found in the patient's lung tissue.
  • The patient received immunotherapy after surgery and lost 20 kg within 9 months. His general condition was poor.
  • Among the 17 reviewed DIM cases, 15 of 17 (88.2%) were male and 2 of 17 (11.8%) were female. Ages ranged from 44 to 81, with a median of 67.
  • Among the 17 reviewed cases, 6 had a history of asbestos exposure. The article prints this as 37.5% (6/17).
  • Among the 17 reviewed cases, 12 of 17 (70.6%) had lesions in both lungs and 9 of 17 (52.9%) had pleural effusion.
  • Among the 17 reviewed cases, 8 of 17 (47.1%) showed a mainly lepidic growth pattern.
  • From the reviewed cases, the authors reported a median survival of five months for DIM: 4 weeks in untreated patients and 5 to 12 months after surgery or chemotherapy.
• The authors' conclusion: The authors concluded that DIM is a rare type of pleural mesothelioma that closely mimics lung adenocarcinoma under the microscope. They added that its prognosis is poor, that the effect of standard mesothelioma treatments on it is unknown, and that awareness of the disease is essential to avoid misdiagnosis and treatment delays.
• Limitations the authors state:
  • The authors state that too few cases were collected to describe how standard mesothelioma treatments (surgery or chemotherapy) affect DIM prognosis.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer, Mesothelioma.

Medical terms in this study, explained in our Lexicon: Mesothelioma, Adenocarcinoma, Epithelioid, Sarcomatoid, Biphasic Mesothelioma, Pleural Mesothelioma, Interstitial Lung Disease, Pleural Effusion.

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