Cutaneous meningeal heterotopia is a rare cutaneous lesion containing meningothelial cells.
Location:
(1) scalp
(2) lumbosacral region
(3) rarely elsewhere
Clinical feature:
(1) congenital fibrotic plaque or nodule
(2) overlying alopecia in hair-bearing sites
(3) asymptomatic to mildly tender
(4) no or slow growth over time
Histopathologic features:
(1) meningothelial cells in strands and pseudovascular structures
(2) fibrous collagenous stroma interspersed between meningothelial cells
(3) reduction in overlying pilosebaceous structures
Rarely there may be an underlying bone defect or residual stalk connecting to adjacent CNS (if on scalp).
Immunohistochemical reactions:
(1) low positivity for Ki-67
(2) positive for EMA, vimentin and NSE
(3) negative for S100, CD31, CD34, and factor 7-related antigen
The diagnosis requires exclusion of other diagnoses.
