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Malignant meningiomas with epithelial (adenocarcinoma-like) metaplasia: a study of 3 cases
Sushama Patil1, Bernd W Scheithauer, Russell G Strom
1Department of Pathology, Washington University School of Medicine, St. Louis, MO, USA.
Background:
Meningiomas exhibit a wide range of histomorphologic features, including variable mesenchymal and epithelioid phenotypes. Meningiomas also represent the most common host tumors for systemic metastases, particularly carcinomas. Recently, however, 3 unique dural-based neoplasms were encountered, wherein malignant-appearing gland-like structures were intermixed with meningothelial elements, yet genetic data suggested epithelial metaplasia rather than metastatic carcinoma.
Objective:
To describe and characterize a rare meningioma pattern with potential diagnostic pitfalls.
Methods:
In addition to routine clinical, radiologic, and histopathological analyses, cases were studied with immunohistochemistry and fluorescence in situ hybridization (FISH) to elucidate the origins of 2 seemingly disparate tumoral components.
Results:
Immunohistochemistry confirmed an epithelial ontogeny of gland-like structures, with extensive CK7 positivity suggesting possible lung or breast primaries. However, identical losses of chromosomes 1p, 14q, and 22q in meningothelial and epithelial components were identified by FISH, an observation consistent with a monoclonal derivation and supporting the diagnosis of malignant meningioma with adenocarcinoma-like metaplasia. Although this phenomenon was reminiscent of gland-like metaplasia in secretory meningioma, it differed in that the gland-forming cells were cytologically malignant, formed extracellular rather than intracellular lumina, and were unassociated with pseudopsammoma bodies. Nevertheless, intermingled secretory and adenocarcinoma-like features were seen in one case, suggesting some relationship between these 2 forms of epithelial metaplasia.
Conclusion:
Recognition of adenocarcinoma-like metaplasia in meningiomas can prevent a misdiagnosis of metastatic carcinoma, with all its associated implications for patient management.
Insights
Meningiomas can rarely develop malignant gland-like structures due to adenocarcinoma-like metaplasia, not metastatic carcinoma. Recognizing this rare pattern prevents misdiagnosis and ensures appropriate patient management.
Area of Science:
- Neuro-oncology
- Pathology
- Genetics
Background:
- Meningiomas display diverse phenotypes and are common sites for metastasis.
- Rare dural-based neoplasms with malignant gland-like structures and meningothelial elements were observed.
Observation:
- Investigated 3 unique neoplasms using clinical, radiologic, histopathological, immunohistochemical, and FISH analyses.
- Elucidated the origins of both meningothelial and epithelial components.
Findings:
- Immunohistochemistry confirmed epithelial origin of gland-like structures (CK7+).
- FISH revealed identical chromosomal losses (1p, 14q, 22q) in both components, indicating monoclonal origin.
- Identified malignant adenocarcinoma-like metaplasia, distinct from secretory meningioma.
Implications:
- Accurate diagnosis of adenocarcinoma-like metaplasia in meningiomas is crucial.
- Prevents misdiagnosis as metastatic carcinoma, avoiding unnecessary treatments.
- Highlights the importance of genetic analysis in differentiating metaplasia from metastasis.
