27D FISH was performed assess the status of chromosomal arms 22q, 18p, 14q and 1p. Deletions of these arms are associated with meningiomas. In particular, 1p and 14q have been associated with atypical and anaplastic meningiomas as well as a higher risk of recurrence and shorter progression free survival. In this particular case, deletions for 1p, 14q and 22q are detected in both the glandular epithelium and in the interglandular areas supporting both the diagnosis of anaplastic meningioma and an identical clonal origin within the glandular element. Chromosome 18 studies were of poor quality, but suggested polysomy 18 (chromosomal gain). ---- Comment: Meningiomas may rarely display epithelial-like differentiation (i.e., metaplasia). Secretory meningiomas contain CEA and cytokeratin positive tumor cells with intracellular lumina, lined ultrastructurally by microvilli, and surrounding eosinophilic structures called pseudopsammoma bodies. These structures are not seen in this particular case. Similarly, anaplastic meningiomas may display carcinoma-like cytology. However, outright malignant glandular metaplasia simulating adenocarcinoma has not been previously described in the literature. The finding of a characteristically meningiomatous profile of chromosomal deletions in both the meningiomatous and glandular areas supports a common origin for these tumor cells and argues against the alternative differential diagnosis of a carcinoma metastatic to a meningioma.
