BAP1-deficient meningioma presenting with trabecular architecture and cytokeratin expression: a report of two cases and review of the literature

AimsBRCA (BReast CAncer gene)-associated protein 1 (BAP1), encoded by the BAP1 gene, a tumour suppressor that is lost in several cancers. Importantly, such mutations have been shown to be susceptible to poly (ADP-ribose) polymerase (PARP) inhibition in preclinical studies, offering hope for targeted therapy. While rare, BAP1 loss has been observed in a subset of rhabdoid and papillary meningioma and is associated with earlier recurrence. We seek to add to the literature on this rare disease and advocate for more routine BAP1 testing.MethodsWe present a report of two cases of BAP1-deficient meningioma and review the available literature on this rare entity.ResultsBoth cases present with a distinct trabecular architecture without rhabdoid or papillary features. Interestingly, both also presented with radiographic and histopathological findings unusual for meningioma. While immunohistochemistry and genetic sequencing confirmed BAP1 loss, DNA methylation analysis was required to confirm the final diagnosis.ConclusionsWe suggest that BAP1-deficient meningioma should be considered in the differential diagnosis of extra-axial central nervous system (CNS) tumours with atypical imaging or histopathological features and that BAP1 loss may constitute a clinically important meningioma subtype with opportunities for targeted therapy.

FDG avid cerebellar atypical meningioma masquerading as solitary brain metastases in a recently diagnosed breast malignancy: a toss between MR and CT

Background SUV Max is a glycolytic index obtained from PET imaging, relates to tumour cell proliferation. FDG uptake (i.e. SUV max) is found to be high in aggressive tumours and is used to identify malignant from benign pathologies. Meningiomas are intracranial tumours which display varying grades of FDG avidity based on its biological aggressiveness. Benign grade I meningiomas are FDG non-avid, while the rest of the typical and atypical meningiomas show varying degrees of FDG avidity. Uptake of FDG can be high in certain infectious and inflammatory brain etiologies and pose a diagnostic challenge in differentiating benign brain lesions from neoplasms. MRI is the preferred modality for accurately identifying meningiomas, providing superior contrast differentiation and its ability to differentiate extra-axial from intra-axial brain lesions. CT is said to be superior in specific types of meningioma where there is calcification and adjacent changes in calvarium. Although typical meningiomas have characteristic MRI features, care must be taken to avoid misleading diagnosis between brain tumours and atypical meningiomas. Case presentation We are presenting a recently diagnosed case of invasive breast carcinoma (Ca) referred for staging by PET/MR imaging. Based on atypical DWI and ADC map findings, MRI falsely reported an atypical meningioma as a brain metastasis. Abnormal intense FDG uptake was noted in a well-defined homogeneously enhancing mass lesion in posterior fossa in left paramedian aspect and broad base to left transverse sinus protruding into left cerebellar hemisphere. Atypical meningioma Grade III, i.e. papillary meningioma was later histologically proven. Conclusions We wish to highlight the inconsistency of DWI and ADC map MR findings in papillary meningioma masquerading as solitary brain metastases in a Ca breast patient on 18F FDG PET/MR imaging. From an imaging standpoint, it is important to recognize the variable and pleomorphic features exhibited by meningiomas in MR based on atypical location, histological subtypes, and biologic behaviours. Further FDG PET was incremental in displaying a high SUV max indicating biologic aggressiveness of lesion and correlating with the CT diagnosis of papillary meningioma.

Papillary Meningioma: Case Presentation with Emphasis on Surgical and Medical Therapy of a Rare Variant of Meningioma

Meningioma is one of the most frequent neoplasms of all in the central nervous system. Different variants are known, and of these some have peculiar characteristics, both from a morphological point of view and from a biological point of view. Here, we present a rare case of relapsed papillary meningioma in a young patient, focusing on histological characteristics, medical-surgical therapy and focusing on the risk of progression and/or recurrence of the lesion if not completely eradicated. Finally, we provide detailed molecular characteristics of the case in question.

Papillary meningioma: a rare cause of massive supratentorial intracerebral hemorrhage

Papillary meningioma (PM) represents a very rare histological subtype, which may present with massive intracerebral hemorrhage. Gross total tumor resection results in a lower recurrence rate and mortality. A 69-year-old man had been experiencing headache for 6 months. After exacerbating right frontal headache, he was brought to the emergency room. His Glasgow Coma Scale (GCS) was 11/15 and he had a left-sided hemiparesis. A computed tomography brain scan revealed a massive right frontal intracerebral hematoma with transtentorial herniation. During right frontal craniotomy and blood clot evacuation, a fleshy, pigmented tissue was encountered. Histopathological findings were consistent with PM World Health Organization Grade III. Complete tumor resection, Simpson II was achieved with a second operation. The hemiparesis and GCS normalized subsequently. The diagnosis of PM relies largely on histopathology and is not commonly encountered preoperatively in emergency cases. Staged surgery in this case resulted in a good outcome.