A variant of encephalomeningocele: heterotopic brain tissue on the scalp.

A 2-year-old girl having a bald nodule on the scalp is reported. The tumor was circular, hemispherically elevated and had a dull reddish color. Roentgenologic studies revealed a defect of the underlying skull bone, and spina bifida occulta on the first and second sacral vertebra were found. Craniotomy was carried out. The tumor extended into the falx cerebri and reached to the tentorium cerebelli, and was not connected with the cerebrum. Histological examination showed insular brain tissue containing glial cells in the lower dermis. Around this tissue, there seemed to be vascular leptomeninges with numerous melanocytes and thickened fibrous elements, probably dura. From these findings, this case was diagnosed as a variant of encephalomeningocele, and as melanocytes physiologically exist on the leptomeninges, melanocytes in an encephalomeningocele may diagnostically identify the leptomeninges.