Intrapulmonary Biphasic Mesothelioma Misdiagnosed as Adenocarcinoma: Case Report and a Potential Diagnostic Pitfall

Our plain-English summary of Intrapulmonary Biphasic Mesothelioma Misdiagnosed as Adenocarcinoma: Case Report and a Potential Diagnostic Pitfall, by W. Xu, X. Zhu, H. Tang, et al (OncoTargets and Therapy, 2024).

The study

• Authors: W. Xu, X. Zhu, H. Tang, Q. Ying, Y. Xu, D. Guo
• Journal: OncoTargets and Therapy
• Published: 2024;17:925-931
• Type of article: Case report
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Mesothelioma is an uncommon malignant tumor with variable clinical presentations, radiological features, and morphological patterns. Mesothelioma with predominantly intrapulmonary growth presents with an insidious onset, similar radiological and even morphological features to lung cancer, and poses a diagnostic pitfall.

Case Presentation: Herein, we reported a 53-year-old female with biphasic mesothelioma misdiagnosed as poorly differentiated adenocarcinoma with focal sarcomatoid carcinoma. Computed tomography (CT) scan of the chest at the first visit revealed a solid lobulated nodule in the basal segment of the lower lobe of the right lung, which was suspicious of lung cancer. Microscopically, the tumor was composed of epithelioid and spindle cells, both of which were diffusely and strongly positive for CK7, and negative for TTF-1, Napsin A, P40, Melan A, S-100, SMA, and CD34. It was originally misdiagnosed as poorly differentiated adenocarcinoma with focal sarcomatoid carcinoma at initial presentation. Until her second admission with the discovery of a nodule in the right diaphragmatic angle, the peculiar location and biphasic component reminded us of biphasic mesothelioma. Immunohistochemically, tumor cells in both pulmonary and diaphragmatic nodules were positive for calretinin, D2-40, and WT-1, but negative for BerEP4 and MOC31. The patient was treated with a chemotherapy regimen of pemetrexed and carboplatin. After 11 months of follow-up, the patient recovers well without recurrence or metastasis.

Conclusion: Mesothelioma with predominantly intrapulmonary growth is extremely rare and poses a diagnostic pitfall. For this entity, subtle morphological features, selection of immunohistochemical markers, and electron microscopy are of great significance for definite diagnosis.

© 2024 Xu et al.

In plain English

This was a case report, with a short literature review, from a pathology department in Guiyang, China. It described a 53-year-old woman with no symptoms and, the article states, no history of smoking or asbestos exposure. A chest CT scan showed a 20 × 15 mm nodule in the lower lobe of her right lung, which radiologists suspected was lung cancer. The nodule was removed in February 2022 and diagnosed as poorly differentiated adenocarcinoma with focal sarcomatoid carcinoma, and she was treated with albumin-paclitaxel and nedaplatin. Twenty-one months after surgery, a 23 × 12 mm nodule was found in the right diaphragmatic angle. Its appearance and staining (positive for calretinin and D2-40, negative for BerEP4 and MOC31) were the same in the lung tumor. This led to a diagnosis of biphasic mesothelioma. She was then given pemetrexed and carboplatin. After 11 months of follow-up she was reported to be recovering without recurrence or metastasis. The authors concluded that this kind of mesothelioma is rare and can be mistaken for lung cancer. They said cell features, choice of stains and electron microscopy can aid 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 of one patient, with a literature review table of previously reported cases
• Who was studied: One 53-year-old woman without symptoms, admitted on 14 February 2022 to Guiqian International Hospital, Guiyang City, Guizhou Province, People's Republic of China, for a right lower lung nodule
• Exposure: The article reports that the patient had no history of asbestos exposure (and no smoking history). No fiber type or asbestos exposure was studied.
• Main results:
  • Chest CT showed a solid lobulated nodule measuring 20 × 15 mm in the basal segment of the lower lobe of the right lung, which radiologists considered suspicious of primary lung cancer
  • After lobectomy, the tumor's epithelioid and spindle cells stained strongly for CK7 and were negative for TTF-1, Napsin A, P40, Melan A, S-100, SMA and CD34. The initial diagnosis was poorly differentiated adenocarcinoma with focal sarcomatoid carcinoma.
  • The patient was first treated with albumin-paclitaxel and nedaplatin as an outpatient
  • The patient was readmitted 21 months after surgery with a nodule in the right diaphragmatic angle, measuring approximately 23 × 12 mm on chest CT
  • Tumor cells in the diaphragmatic nodule were diffusely positive for calretinin and D2-40 and focally positive for WT-1 and GATA-3. They were negative for CK5/6, BerEP4, MOC31 and BAP-1. The lung lesion showed the same results, and the diagnosis was revised to biphasic mesothelioma.
  • The patient then received pemetrexed and carboplatin. After 11 months of follow-up she was reported to be recovering well without recurrence or metastasis.
  • The literature review table listed 14 previously reported cases of mesothelioma with predominantly intrapulmonary growth. Asbestos exposure was recorded as yes for 2 cases (Guo X et al and Muramatsu Y et al), no for 10, and not known for 2.
• The authors' conclusion: The authors concluded that this entity is rare and resembles primary lung cancer on imaging and even on tissue examination, which makes diagnosis challenging. They stated that subtle cell features, the choice of immunohistochemical markers, and electron microscopy can aid definite diagnosis in difficult cases.

Topics

Medical terms in this study, explained in our Lexicon: Biphasic Mesothelioma, Adenocarcinoma, Mesothelioma, Lung Cancer, Sarcomatoid, Carcinoma, Epithelioid, Spindle Cell.

Related studies

• Expression of Calretinin, Marker of Mesothelial Differentiation, in Pancreatic Ductal Adenocarcinoma: A Potential Diagnostic Pitfall — G. Askan, O. Basturk (2021)
• Peritoneal mesothelial hyperplasia associated with gynaecological disease: a potential diagnostic pitfall that is commonly associated with endometriosis — R. Oparka, W.G. McCluggage, et al. (2011)
• Pulmonary sclerosing hemangioma presenting with dense spindle stroma cells: a potential diagnostic pitfall — X.Y. Lin, Y. Wang, et al. (2012)
• Gene Expression Analysis of Biphasic Pleural Mesothelioma: New Potential Diagnostic and Prognostic Markers — R. Bruno, A.M. Poma, et al. (2022)
• A Comprehensive Pan-Cancer Analysis Reveals Cyclin-Dependent Kinase Inhibitor 2A Gene as a Potential Diagnostic and Prognostic Biomarker in Colon Adenocarcinoma — A. Salem, S. Ahmed, et al. (2024)
• Pan-cancer profiles of mesothelin (MSLN) unveil diagnostic potential and therapeutic targetability of pancreatic adenocarcinoma — M.R. Sheikh, B. Mistry, et al. (2026)

Browse more research in OncoTargets and Therapy, or return to medical research.