A single case history is worthy of report if it presents a previously unrecognized condition or if it sheds further light on unproven concepts of pathogenesis or treatment. The present case seems to fulfill both criteria. Congenital cutaneous defects of the scalp are quite rare. When they occur they appear as variously discolored areas completely devoid of hair, usually over the vertex of the head. They range in size from circular lesions 1-2 cm. in diameter to large defects embracing both anterior and posterior fontanelles and a narrower area of the scalp between. Usually there is no associated defect in the underlying skull, but in a number of instances such a defect has been present and, in some, there may be a direct connection with a major blood vessel such as the sagittal sinus. Though less common than those in the scalp, congenital cutaneous defects have been observed in many parts of the body including the trunk and extremities, and such lesions are usually neither bilaterally symmetrical nor localized to the midline. The etiology is unknown and may not be the same in all cases, but the previously accepted theory that they result from inflammatory adhesions between the amnion and body surface has been largely discarded. Whatever their origin they probably differ from the midline defects which occur anywhere from the cranium to the sacrum. An associated lesion which has recently received wide recognition in British and American literature is the congenital dermal sinus which connects the body surface with the meninges or central nervous system. It is possible that many of the reported cases of isolated cutaneous midline defects may have had such a connection which was overlooked. Dermal sinuses arc presumably related to the case under consideration. In the present instance the lesion was believed, pre-operatively, and even at operation, to be an isolated congenital cutaneous defect without any transcranial connection. The correct diagnosis, derived from microscopic examination of the tissue, was unexpected. A reasonably comprehensive search of the literature revealed no identical case, but there can be no doubt that there is a direct correlation between this and certain previously recognized lesions. The case is therefore of interest with respect to differential diagnosis and management, and it is pertinent to some currently unsolved problems in the fields of embryology and neuropathology.