Meningeal hamartoma of the scalp. A variant of primary cutaneous meningioma.

A case of meningeal hamartoma of the scalp is reported. A 15-year-old girl was admitted complaining of scalp nodules in the midline occipital region. A midline skull defect was found under the nodular lesions. Histologically, the mass had a fibrocollagenous tract extending to the dura and showed an admixture of mature adipose tissue, small vessels, strands of fibrocollagenous tissue, and scattered foci of meningocytes. Immunohistochemically, the meningocytes desmosomes, interdigitating processes, and intermediate filaments. The patient's brother also had the meningeal hamartoma of the scalp. Meningeal hamartoma as a variant of primary cutaneous meningioma is extremely rare, and this is the first report of such a case in Japan.