Congenital nevus and lipoma overlying sacrum. Imaging is indicated to excluding an underlying dysraphism.
Spinal dysraphism refers to developmental abnormalities of the spine and spinal cord. These birth defects may be obvious (e.g. meningomyelocele) or occult. Occult SD often has cutaneous manifestations, e.g. dimples, lipomas, localized hypertrichosis, angiomas, neurofibromas, and congenital melanocytic nevi. Vascular birthmarks/hemangiomas, port-wine stains, nevus flammeus simplex, medial telangiectatic vascular naevi, stork bites, and salmon patches are some of the terms that have been used to describe erythematous macules found along the vertebral column. The pulling of the spinal cord at the base of the spinal canal, literally a tethered cord, is a common part of occult spinal dysraphism. See also Lumbar syndrome.
A congenital vascular stain over the low back always brings up the question of possible spinal dysraphism.
Meningomyelocele. A meningomyelocele is a hernial protrusion of the spinal cord and its meninges through a defect in the vertebral arch and is one of the most common forms of spina bifida. Courtesy O. Dale Collins, MD