Metastatic rhabdoid meningioma of the parotid - Mimicking primary salivary gland neoplasm.

INTRODUCTION: Tumors 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 CASE: A 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.

DISCUSSION: Morphologically, 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.

CONCLUSION: Rhabdoid 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.