Case of Metastatic Atypical Meningioma to Lung: Utility of Cytological Preparations for Intraoperative Diagnosis

Abstract

Abstract Introduction/Objective Meningiomas are the most common primary intracranial and intraspinal tumors. They are typically benign with an indolent behavior but can metastasize extracranially to the skin, bone, lymph node and liver. Lung metastasis is exceptionally rare, and the diagnosis can be challenging, especially during intraoperative diagnosis without ancillary studies. We describe a metastatic atypical meningioma to the lung for which intraoperative cytology facilitated the diagnosis and guided management. Methods/Case Report A 53-year-old woman with a history of left frontal atypical meningioma and multiple surgical resections for recurrences at outside hospitals, presented with an incidental left lung nodule. A lung wedge resection was performed and submitted for intraoperative diagnosis. Gross examination revealed a well-circumscribed, tan- white, and rubbery subpleural nodule. Cytological preparations— Diff-Quik and H&E stains—and frozen section were prepared. Cytologically, the nodule displayed cohesive distinctive papillary whorls of uniform eosinophilic cells with indistinct cell membranes, round to oval nuclei with central nucleoli and intranuclear pseudoinclusions. The frozen section exhibited similar cytological features, few identifiable whorls and predominantly solid sheets of tumor cells typical of non-small cell carcinoma. Based primarily on the cytological findings, the intraoperative diagnosis was a neoplasm with papillary growth pattern, and a metastasis was favored based on the whorled pattern and clinical history; no further resection was performed. Permanent sections displayed mitoses and no necrosis. Immunohistochemical analysis revealed positivity for somatostatin receptor 2a, progesterone receptor, and EMA (focal); no staining was seen with pancytokeratin, TTF-1, or p40. A diagnosis of atypical meningioma, WHO grade 2, was rendered. Subsequently, an atypical cranial and temporalis muscle meningioma at the site of the prior craniotomy bone flap was resected and had an identical molecular profile (1p36 deletion) to that in the lung, further supporting metastasis to the lung. Results (if a Case Study enter NA) NA Conclusion This case illustrates a rare presentation of metastatic atypical meningioma and highlights the distinctive intraoperative utility of cytology preparations—architectural and cytological details—for diagnosis and appropriate management. Cytology preparations can be a valuable tool and complement frozen sections, in which certain morphological features may be less obvious or confounded by freezing artifact.