Malignant mesothelioma with prominent adenomatoid features: a clinicopathologic and immunohistochemical study of 10 cases

Our plain-English summary of Malignant mesothelioma with prominent adenomatoid features: a clinicopathologic and immunohistochemical study of 10 cases, by A. Weissferdt, N. Kalhor, S. Suster (Annals of Diagnostic Pathology, 2011).

The study

• Authors: A. Weissferdt, N. Kalhor, S. Suster
• Journal: Annals of Diagnostic Pathology
• Published: 2011;15(1):25-9
• Cited by: 24 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The clinicopathologic and immunohistochemical features of 10 cases of pleural malignant mesothelioma with predominantly adenomatoid growth pattern are described to determine the clinical, histologic, and behavioral features of these tumors and to highlight the importance of separating this unusual pattern from the benign adenomatoid tumor. Seventy-seven cases of pleural biopsy and extrapleural pneumonectomy specimens for malignant mesothelioma were examined to identify the specific type of histologic growth pattern exhibited by the tumors. The 10 cases herein described were identified as an unusual histopathologic subset of these tumors. Nine patients were men and one was a woman with an age range of 56 to 82 years (mean, 68.5 years). The main presenting symptoms included cough, dyspnea, and chest pain. The typical features of pleural malignant mesothelioma were noted both radiologically and macroscopically. The tumors were characterized by diffuse pleural thickening with confluent nodular patches of tumor obliterating the pleural space. Histologically, a distinct morphology was observed composed of small tubular spaces lined by epithelioid cells, reminiscent of adenomatoid tumors of the genital tract. Immunohistochemical studies confirmed the mesothelial nature of the tumors. Clinical follow-up in 7 of 7 patients demonstrated a mean survival of 10 months from time of diagnosis. Adenomatoid mesothelioma is an unusual variant of epithelioid malignant mesothelioma that histologically may mimic a range of other tumors, including benign adenomatoid tumors and metastases of adenocarcinoma to the pleura. The clinical presentation, infiltrative growth, distinct histologic features, cytologic atypia and immunohistochemical profile all serve to differentiate adenomatoid malignant mesothelioma from other infiltrative processes involving the pleura.

Copyright © 2011 Elsevier Inc. All rights reserved.

In plain English

This was a pathology case series describing 10 patients with pleural malignant mesothelioma whose tumors grew mostly in an "adenomatoid" pattern, which resembles a benign tumor of the genital tract. The cases came from the files of MD Anderson Cancer Center in Houston and from the consultation files of one author. Nine patients were men and one was a woman, aged 56 to 82 (mean 68.5 years). Three patients had known asbestos exposure. The article does not describe the type of asbestos or how the exposure occurred. Under the microscope, all tumors invaded surrounding tissue, and the adenomatoid pattern made up roughly 75% to 80% of the tumor. Tumor cells stained for keratin, CK5/6 and calretinin, which the authors took as confirming mesothelial origin. Of the 9 patients with follow-up, 7 died of their disease, with a mean survival of 10 months after diagnosis, and 2 were alive at 5 and 11 months. The authors concluded that this variant behaves like other epithelioid mesotheliomas and matters because it can be misdiagnosed as other tumors.

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 series (clinicopathologic and immunohistochemical study of 10 cases)
• Who was studied: 10 patients with pleural malignant mesothelioma with a predominantly adenomatoid growth pattern (9 men, 1 woman, aged 56 to 82 years, mean 68.5), from the surgical pathology files of MD Anderson Cancer Center, Houston, Texas, and the consultation files of one author. Dates are not given.
• Exposure: Asbestos exposure was reported for 3 of the 10 patients (cases 3, 4 and 10 in Table 1). The article gives no fiber types, products, jobs or doses.
• Main results:
  • All tumors grew infiltratively, invading the fat of the parietal pleura, the lung tissue, or the diaphragm muscle.
  • In all cases the adenomatoid pattern made up approximately 75% to 80% of the tumor mass.
  • Mitotic activity (dividing cells) was found in all 10 cases, ranging from 1 to 11 mitoses per 10 high power fields.
  • Tumor cells stained strongly positive for broad-spectrum keratin, CK5/6 and calretinin. All other markers tested (CEA, CD15, MOC31, B72.3, TTF1) were negative.
  • After diagnostic biopsy, 7 patients had extrapleural pneumonectomy, 2 were treated palliatively, and 1 was being evaluated for extrapleural pneumonectomy.
  • Seven patients died of their disease, with a mean survival of 10 months from diagnosis. The 2 most recently diagnosed patients were alive at 5 and 11 months. Follow-up was not available for one patient.
• The authors' conclusion: The authors concluded that, clinically and in prognosis, adenomatoid mesothelioma does not differ from other variants of epithelioid mesothelioma. In their view, recognizing it matters because it can be mistaken for other benign and malignant pleural tumors.

Topics

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

Medical terms in this study, explained in our Lexicon: Malignant Mesothelioma, Adenomatoid Tumor, Pleural Biopsy, Extrapleural Pneumonectomy (EPP), Dyspnea, Diffuse Pleural Thickening, Epithelioid, Mesothelioma.

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