Dorsal midline ectopic mammary tissue as a cutaneous marker of spinal dysraphism: intradural lipoma and tethered cord in a child with literature review

PURPOSE: Supernumerary breasts (polymastia) and supernumerary nipples (polythelia) are congenital anomalies resulting from incomplete regression of the embryonic mammary ridge. They most frequently occur along the embryologic milk line extending from the axilla to the groin. Ectopic localization outside this line is rare, and dorsal presentations are exceptional. In such cases, an association with underlying spinal dysraphism has occasionally been reported. METHODS: We report the case of an 11-year-old girl presenting with a congenital dorsal midline swelling initially diagnosed as a lipoma. Progressive enlargement and the appearance of a central pigmented structure prompted further evaluation. Clinical examination confirmed a dorsal midline areola-nipple complex with underlying tumefaction. Spinal MRI demonstrated an intradural lipoma at the T4 level associated with a fibrous tract extending toward the cutaneous lesion, resulting in a tethered cord configuration. RESULTS: The patient underwent combined resection of the ectopic mammary tissue and neurosurgical detethering with partial lipoma resection. Postoperative recovery was uneventful with no neurological deficit. CONCLUSION: Dorsal midline ectopic mammary tissue is extremely rare and may represent a cutaneous marker underlying spinal dysraphism. Careful clinical examination and spinal imaging should therefore be considered in such atypical presentations.