Metastatic rhabdoid meningioma of the parotid – Mimicking primary salivary gland neoplasm

Abstract

INTRODUCTIONTumors involving the parotid are predominantly primary with metastatic lesions forming a miniscule population. Meningioma metastasizing to the parotid is extremely rare and hence can often be mistaken for the more common primary salivary gland neoplasms.PRESENTATION OF CASEA 59-year-old male presented with a swelling in the left parotid region. Fine needle aspiration cytology was suggestive of myoepithelial predominant pleomorphic adenoma. A superficial parotidectomy performed revealed a tumor composed of rhabdoid cells with abundant finely granular eosinophilic cytoplasm raising a possibility of myoepithelioma. Immunohistochemistry for myoepithelial markers was negative. A critical review elicited a history of surgical excision of a recurrent rhabdoid meningioma twice. A possibility of metastasis was considered and a second panel of immunomarkers demonstrated vimentin and epithelial membrane antigen positivity. Neuroimaging studies demonstrated a space occupying lesion in the frontal lobe suggestive of a recurrent/residual tumor. In view of the history, neuroradiology, histopathology and immunohistochemistry, a final diagnosis of metastatic rhabdoid meningioma to the parotid was rendered.DISCUSSIONMorphologically, metastatic rhabdoid meningioma may mimic a primary or metastatic carcinoma, melanoma and sarcoma. Accurate diagnosis can be made by careful clinical evaluation and histopathological examination of the tumor. These tumors are composed of rhabdomyoblast like cells with abundant eosinophilic cytoplasm. The present case demonstrated characteristic histopathological features confirmed by immunohistochemistry.CONCLUSIONRhabdoid meningioma is an aggressive tumor with a high propensity to recur and metastasize. The present case highlights the importance of clinical, radiological and histopathological correlation to accurately diagnose these rare entities.

Widespread intra-abdominal carcinomatosis from a rhabdoid meningioma after placement of a ventriculoperitoneal shunt: A case report and review of the literature

“…[ 10 ] Extraneural metastasis to the lung, parotid gland, and liver have been reported and are most likely due to hematogenous seeding. [ 10 11 12 ] Tumor dissemination via VPS to the peritoneal cavity causing widespread intra-abdominal carcinomatosis have been reported in CNS tumors of other histological cell types, but to our knowledge, not in rhabdoid meningioma. In our case, we believe that the VPS was the conduit for the transcelomic spread of malignant cells that were present in the CSF into the peritoneal cavity leading to widespread intra-abdominal carcinomatosis.…”

Frequency of BRAF V600E mutations in 969 central nervous system neoplasms

“…All other anaplastic meningiomas WHO grade III of this cohort showed no evidence of V600E mutation (0/24). Rhabdoid meningiomas may also display some epithelial qualities of the tumor cells on histopathological examination, similar to the epithelioid glioblastoma variant, but these tumors can be easily distinguished by immunohistochemistry for epithelial membrane antigen and glial fibrillary acidic protein (GFAP) [ 42 , 43 ]. Just recently, a case of a BRAF mutated, metastasizing rhabdoid meningioma in a comatose child discovered by panel sequencing was reported [ 44 ].…”

Widespread intra-abdominal carcinomatosis from a rhabdoid meningioma after placement of a ventriculoperitoneal shunt: A case report and review of the literature

“…[ 10 ] Extraneural metastasis to the lung, parotid gland, and liver has been reported and is most likely due to hematogenous seeding. [ 10 11 12 ] Tumor dissemination through VPS to the peritoneal cavity causing widespread intra-abdominal carcinomatosis has been reported in CNS tumors of other histological cell types, but to our knowledge, not in rhabdoid meningioma. In our case, we believe that the VPS was the conduit for transcoelomic spread of malignant cells that were present in the CSF into the peritoneal cavity leading to widespread intra-abdominal carcinomatosis.…”