Heterotopic Cutaneous Meningioma: An Unusual Presentation Occurring in a Patient With a Remote History of Intracranial Meningioma.

Meningioma is a neoplasm of the meninges, which usually occurs in intracranial sites. Extracranial meningioma has been frequently reported in the sinonasal tract and skull bone, often as extension of intracranial meningiomas. Isolated heterotopic meningioma without contiguous intracranial lesion is extremely rare. A 56-year-old woman presented in December 2015 with 2 firm subcutaneous scalp masses; one in the left lateral (temporal) and the other in the left superior (parietal) region. The clinical impression was that of lipoma. Pathologic examination revealed an ill-defined proliferation of uniform meningothelial cells in a fibroblastic stroma interspersed within adipose tissue. The excised lesions had similar histologic features. Immunohistochemical stains were performed and the tumor cells were positive for epithelial membrane antigen and negative for S-100. A diagnosis of extracranial meningioma, WHO grade I was made. The patient's medical history was significant for intracranial meningioma of the frontal lobe in October 2007, which was diagnosed as atypical meningioma, WHO grade II. Comparison of the scalp masses to her previous meningioma revealed a distinctly different morphologic pattern. In light of the 8-year interval between the scalp and intracranial meningioma and the difference in histologic grades, it is unlikely that her most recent tumors represent a recurrence or metastasis of the intracranial tumor.