Adenomatoid Tumor

An adenomatoid tumor is a small, benign growth that arises from mesothelial cells, the same cells that line body cavities and that, when malignant, cause mesothelioma. They are most often found in the reproductive tract but can also occur in the pleura or peritoneum. They grow slowly, do not spread, and are typically discovered incidentally.

Origin

The term was coined in 1945 by pathologist Pierre Masson, who described these lesions as having a glandular ('adeno-') appearance under the microscope, though they are not true glands. The mesothelial origin of adenomatoid tumors was later confirmed in the 1970s and 1980s using immunohistochemistry and electron microscopy.

Significance in Asbestos Context

For patients and their doctors, the most important issue with an adenomatoid tumor is distinguishing it from mesothelioma, because both arise from mesothelial cells and can look similar on initial imaging or biopsy. A misread biopsy can go in either direction, a benign adenomatoid tumor wrongly called mesothelioma, or, more dangerously, an early mesothelioma wrongly called adenomatoid. This is why expert mesothelial pathology review and immunohistochemical staining (markers such as calretinin, WT-1, and BAP1) are critical. If you have a history of asbestos exposure and a mesothelial lesion is found anywhere in your body, push for review by a pathologist experienced in mesothelioma; the distinction changes everything about treatment, prognosis, and whether you have a legal claim.

Example Sentence

After his pleural nodule was biopsied, the patient asked for a second pathology review at a mesothelioma center to confirm it was an adenomatoid tumor and not an early mesothelioma.

Related Terms

Mesothelioma, Mesothelial Cells, Immunohistochemistry, BAP1, Well-Differentiated Papillary Mesothelioma, Pathology Review

Notes

• If a biopsy returns 'adenomatoid tumor' and you have any asbestos exposure history, request a second opinion from a pathologist at a recognized mesothelioma center (such as Brigham and Women's, MD Anderson, or a NCI-designated cancer center).
• Ask your pathologist specifically whether BAP1 immunostaining was performed; loss of BAP1 strongly suggests malignancy rather than a benign adenomatoid tumor.
• Keep copies of the original pathology slides and the written report. These can be sent out for expert review and are essential evidence if the diagnosis is later revised to mesothelioma.
• Even after a confirmed benign diagnosis, continue any recommended imaging follow-up; an asbestos-exposed patient remains at elevated lifetime risk for true mesothelioma elsewhere.