Secretory meningioma, a rare meningioma subtype with characteristic glandular differentation: an histological and immunohistochemical study of 9 cases.

AIM: We studied the immunophenotype of 9 cases of secretory meningioma (SM), a rarely reported meningioma variant, characterized by small gland-like lumina filled with a PAS-positive, diastase-resistant substance.

METHODS

Three samples of arachnoid tissue and 9 SMs were studied with a panel of monoclonal antibodies (MoAbs) against cytokeratins (Ck) 7,8, 20, vimentin, EMA, CEA and the mucin epitopes sialyl-Tn, Tn, CA19.9, CA125, against the BerEP4 and CD15; 3 colonic adenocarcinomas metastatic to the brain and a case of meningioma with metastasis from a gastric signet-ring cell carcinoma were also studied with the same panel of MoAbs for comparison.

RESULTS

The 3 samples of arachnoid cap cells were positive only for EMA and vimentin in the supportive stroma. All 9 SMs resulted Ck7+, Ck8+, Ck20-, EMA+, CEA and mucin epitopes+, confirming at an immunohistochemical level the glandular differentiation. Notable exceptions were the negativity for BerEP4 and CD15 antigens. Conversely, the 3 metastatic colonic adenocarcinomas to the brain were Ck7-, Ck8+, Ck20+, CEA and mucin epitopes+, BerEP4 and CD15+; the gastric signet-ring cell carcinoma metastatic to a meningioma showed the same immunophenotype as the other metastatic adenocarcinomas with the exception of BerEP4 negativity.

CONCLUSION

The different pattern of cytokeratin expression (Ck7+/Ck20- for SMs, and Ck7-/ Ck20+ for adenocarcinomas) and the negativity for BerEP4 and CD15 epitopes of SMs, could be relevant for the distinction between SMs and metastatic adenocarcinomas.