Localized malignant pleural mesothelioma arising in the interlobar fissure: a unique surgical case masquerading clinicopathologically as primary lung adenocarcinoma

Our plain-English summary of Localized malignant pleural mesothelioma arising in the interlobar fissure: a unique surgical case masquerading clinicopathologically as primary lung adenocarcinoma, by X. Guo, J. Watanabe, K. Takahashi, et al (SAGE Open Medical Case Reports, 2019).

The study

• Authors: X. Guo, J. Watanabe, K. Takahashi, T. Hayashi, N. Kurose, Y. Sasaguri, H. Uramoto, H. Iwagaki, K. Nabeshima, S. Yamada
• Journal: SAGE Open Medical Case Reports
• Published: 2019;7:2050313X18824802
• Type of article: Case report
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

An 80-year-old male with previous workplace exposure to asbestos presented with a history of an increase in the pulmonary-to-hilar mass, measuring more than 50 mm in diameter, likely in the right lower lobe. We first interpreted it as suspicious of primary lung adenocarcinoma with direct invasion to the right hilar lymph node. A right middle and lower lobectomy with partial resection of upper lobe was performed, and gross examination showed a hilar tumor lesion, involving the middle/lower lobe to hilar lymph node and looking whitish to yellow-grayish, partly adjacent to the right pulmonary artery. On microscopic examination, the tumor was located on the extrapulmonary, interlobar pleural fissure, predominantly composed of a proliferation of atypical epithelioid cells, often arranged in an irregular and fused tubular growth pattern with an involvement of pulmonary artery. Immunohistochemically, these atypical cells are positive for several mesothelial markers, including calretinin, cytokeratin 5/6, and WT-1, whereas negative for thyroid transcription factor 1. Furthermore, p16 deletions were specifically detected by fluorescence in situ hybridization, and electron microscopy showed numerous, significantly elongated microvilli. Taken together, we finally made a diagnosis of localized malignant pleural mesothelioma, epithelioid-type, arising in the right interlobar fissure between lower and middle lobes. We should be aware that, owing to its characteristic features, clinicians and pathologists might be able to raise interlobar fissure localized malignant pleural mesothelioma as one of the differential diagnoses, based on careful clinicopathological examinations.

In plain English

This case report from Japan described one patient: an 80-year-old man with previous workplace exposure to asbestos, who had smoked heavily for over 45 years. The article does not say what type of asbestos. A chest scan showed a mass of about 50 mm near the root of the right lung. Biopsy samples were too small to diagnose, and the doctors first suspected primary lung adenocarcinoma, a type of lung cancer. Surgeons removed the right middle and lower lobes and part of the upper lobe. The tumor measured 55 by 43 by 40 mm. It sat on the lung lining in the fissure between the right middle and lower lobes. Tumor cells were positive for mesothelial markers (calretinin, CK5/6, WT-1) and negative for the lung cancer marker TTF-1. A gene test found p16 deletions, and electron microscopy showed long microvilli. The final diagnosis was localized malignant pleural mesothelioma, epithelioid type. One year after surgery, without chemotherapy or radiotherapy, the patient showed no sign of recurrence. The authors concluded that doctors and pathologists should consider this tumor as a possible diagnosis.

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 (single surgical case)
• Who was studied: One 80-year-old Japanese man, a heavy smoker for over 45 years, with a history of urothelial carcinoma of the urinary bladder 3 years earlier
• Exposure: Previous workplace exposure to asbestos (fiber type, job and dose not stated); also heavy smoking for over 45 years
• Main results:
  • Before surgery, biopsy specimens were too small to be diagnostic, and the tumor was interpreted as highly suspicious of primary lung adenocarcinoma
  • The resected tumor was a lobulated hilar mass measuring 55 mm × 43 mm × 40 mm
  • Under the microscope the tumor lay outside the lung, on the interlobar visceral pleura
  • Tumor cells were positive for mesothelial markers calretinin, cytokeratin 5/6 and WT-1, and negative for TTF-1
  • p16 deletions were detected by FISH, and electron microscopy showed numerous, significantly elongated microvilli
  • Final diagnosis: localized malignant pleural mesothelioma, epithelioid type, in the right interlobar fissure between the lower and middle lobes
  • At 1 year after surgery, without chemotherapy or radiotherapy, the patient remained well with no sign of recurrence
• The authors' conclusion: The authors concluded that, with careful clinical and pathological examination, clinicians and pathologists may be able to raise localized malignant pleural mesothelioma of the interlobar fissure as a differential diagnosis. They suggested it may be more common than generally considered.

Topics

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Lung Adenocarcinoma, Epithelioid, Calretinin, Cytokeratin 5/6, Wilms Tumor 1 (WT-1), Fluorescence In Situ Hybridization (FISH).

Related studies

• The Pathologic Peritoneal Cancer Index (PCI) Strongly Differs From the Surgical PCI in Peritoneal Metastases Arising From Various Primary Tumors — A. Bhatt, Y. Yonemura, et al. (2020)
• Localized mesothelioma tumour arising synchronously with a primary contralateral lung cancer — W. Andrews, S. Paul, et al. (2013)
• Visceral pleural thickening in asbestos exposure: the occurrence and implications of thickened interlobar fissures — S.D. Rockoff, E. Kagan, et al. (1987)
• Thickening of pulmonary interlobar fissures: exposure-response relationship in crocidolite and amosite miners — A. Solomon, L.M. Irwig, et al. (1979)
• CT demonstration of interlobar fissure calcification due to asbestos exposure — S.D. Rockoff (1987)
• Nodular thickening of interlobar fissures: an early manifestation of malignant mesothelioma: a case report — S. Bandoh, J. Fujita, et al. (2001)

Browse return to medical research.