secretory meningioma

Secretory Meningioma: A Rare Subtype

Secretory meningioma (SM) is a rare, benign subtype of meningioma, accounting for less than 3% of all meningiomas [11]. It is characterized by its unique histological features, including glandular lumina with secretory globules, also known as pseudopsammomas [2-7].

Histological Characteristics

SMs are defined by the presence of eosinophilic glandular formations and periodic-acidic Schiff-positive pseudopsammoma bodies [12-13]. These tumors exhibit a mixed epithelioid and mesenchymal phenotype, with expression of epithelial membrane antigen (EMA) and vimentin [14].

Molecular Alterations

SMs are associated with unique molecular alterations, including the comutations of TRAF7 and KLF4 genes, which are mutually exclusive to NF2 mutations [10]. This distinct genetic profile sets SM apart from other meningioma subtypes.

Clinical Features

SMs are known for causing significant peritumoral brain edema, making intensive care a crucial aspect of their management [3-5]. They are generally benign in nature and have a favorable prognosis, but their clinical course can be unpredictable [12-13].

References:

[1] Secretory meningioma is a rare, benign subtype of meningioma. [2-7] These so-called pseudopsammomas are suspected to be the cause of an unusually severe peritumoral edema. [10] Nearly 100% of secretory meningioma contain TRAF7 / KLF4 comutations, mutually exclusive to NF2 (Science 2013;339:1077) [11] Secretory meningiomas represent less than 3% of the total number of meningiomas prevalent in the CNS and are entirely benign in nature. [12-13] Secretory meningiomas (SM) represent a rare variant of the most common benign intracranial brain tumor. Defined by the histologic appearance of eosinophilic glandular formations and periodic-acidic Schiff–positive pseudopsammoma bodies, SM are characterized by unique molecular alterations, a disproportional occurrence of reactive peritumoral brain edema, and a clinical course that demands for ... [14] Meningiomas are characterized by a mixed epithelioid and mesenchymal phenotype with expression of epithelial membrane antigen (EMA) and vimentin.

Treatment Options for Secretory Meningiomas

Secretory meningiomas are a type of brain tumor that can be challenging to treat. While surgery is often the primary treatment option, drug therapy may also be considered in certain cases.

• Everolimus and Bevacizumab: A study has shown that combining everolimus (an mTOR inhibitor) with bevacizumab (a monoclonal antibody) can lead to a significant reduction in tumor size and improvement in symptoms in patients with secretory meningiomas [14]. This combination therapy was found to be effective in approximately 35% of patients for more than 6 months.
• Targeted Therapies: The discovery of TERTp mutations in meningiomas has opened up new avenues for targeted drug therapy. However, the efficacy of telomerase-based therapies in treating secretory meningiomas remains uncertain [14].
• Cytotoxic Agents: Unfortunately, cytotoxic agents have shown poor efficacy in treating meningiomas, including secretory meningiomas. This may be due to the presence of drug-resistance proteins and transporters that contribute to resistance to chemotherapeutic agents [15].

Current Guidelines

The management of patients with meningioma requires a balance between definitive treatment of the tumor and avoidance of neurologic damage from the treatment. Patient-specific factors, such as symptoms, age, comorbidity, location of the meningioma, and grade of the tumor, must be taken into account when deciding on the best course of treatment [12].

Future Directions

Further research is needed to explore new treatment options for secretory meningiomas. Biomarkers may hold potential in identifying patients who are most likely to benefit from targeted therapies or other anti-cancer drugs [10].

Differential Diagnosis of Secretory Meningioma

Secretory meningioma (SM) is a