Meningothelial Hamartoma Associated with Nevus Sebaceus

Abstract

Meningothelial hamartoma is a rare lesion of ectopic meningothelial elements that usually presents on the scalp at birth or in early childhood. The characteristic spindle cells infiltrate through collagen and stain positively for epithelial membrane antigen and vimentin but are negative for CD31 and CD34. This distinguishes meningothelial hamartoma from vascular tumors. Nevus sebaceus is a fairly common lesion that has been associated with several different benign tumors, including trichoblastoma and syringocystadenoma papilliferum. We describe the case of a 17-month-old girl who presented with a meningothelial hamartoma in association with a nevus sebaceus. To the best of our knowledge, this is the second case reported.

Meningothelial hamartoma of the scalp

“…The final diagnosis can be made after surgical removal and histopathological examination. Histologically, meningothelial hamartomas usually arise in the subcutaneous tissue and sometimes the dermis can be involved; however, the epidermis is histologically normal [5]. It is characterized by the proliferation of connective tissue elements and epithelioid cells with pseudoinfiltrative growth pattern.…”

“…Meningothelial hamartoma is a rare benign tumor composed of ectopic meningothelial elements in the dermis and subcutaneous tissue. Since its first description by Suster and Rosai in 1990 [3], it has been reported in at least 17 cases [4,5]. It occurs mainly on the posterior scalp [4].…”

Congenital, Painless Linear Plaque on the Scalp of an 18‐Month‐Old Child

“…It generally presents at birth or in early childhood, with no clear sex or race predilection. To our knowledge, 18 cases have been reported in the international literature . The origin of this hamartoma has yet to be fully understood.…”

“…It might arise from ectopic arachnoid cells displaced during embryogenesis. Alternatively, it could result from a cellular abortive migration from the neural crest or from an extrusion through a pathologic extracranial connection . The clinical behavior is benign and surgical excision is curative.…”

“…Midline neural tube defects must be excluded; a case of extension to the pericranium and a case of extension to the intracranial compartment have been reported to date . Thus ultrasound and magnetic resonance imaging should always be performed to define the extension, to exclude involvement of the underlying bony or intracranial neural tissues , and to exclude associated structural abnormalities in the skull . Ultrasound is a good first‐line examination that can be followed by magnetic resonance imaging when a suspicious sign is noted.…”