Introduction: Accessory breast, also known as supernumerary breasts, polymastia or mammae erraticae, is a clinical condition of having an additional breast. Accessory breast are usually seen along the embryonic milk line, majority being located in the axilla. Polythelia is the presence of an additional nipple. We report a rare case of dorsal accessory ectopic breast with 3 nipples (2 well formed and 1 rudimentary) occurring along with lipomeningomyelocele and diastematomyelia. The association of dorsal accessory breast with lipomeningomyelocele and diastematomyelia has been reported only once in world literature, but the association of dorsal accessory breast with polythelia with lipomeningomyelocele and diastematomyelia has never been reported.

Methods: Case Description: We report a 18 years old female who presented with chief complaints of swelling over the upper back since birth and spastic weakness of bilateral lower limbs with inability to walk since 2 years [Figure 1]. 3D computed tomography scan of the dorsal spine was suggestive of a wide bony defect in the posterior spinal elements from D3 to D9 vertebrae. Diastematomyelia was also seen with a fibrous septum from D3 to D7 vertebrae [Figure 2]. MRI Dorsal Spine was suggestive of a complex spinal dysraphism with lipomeningomyelocele and diastematomyelia [Figure 3]. At surgery, the patient's accessory breast was removed, meningomyelocele sac and fibrous septum was excised. Histopathological examination was consistent with "Accessory ectopic breast with meningomyelocele sac" [Figure 4].

Results: Discussion: Multiple theories have been proposed to explain the occurrence of accessory breast. These include Darwin's theory which stated that, "traits which have disappeared generations before, can reappear", Pfeifer's theory of metaplasia of sweat glands, Hughes theory of migration of primordial breast cells away from the mammary crest and Schultz's theory of displacement of milk lines, laterally or caudally.

Conclusions: We report a rare association of dorsal accessory breast with polythelia with lipomeningomyelocele and diastematomyelia.

Patient Care: As dorsal accessory breast in the midline is a marker of OSD, all patients should be subjected to radiological imaging of the spine before excising the ectopic breast mass.

Learning Objectives: Cutaneous markers of occult spinal dysraphism (OSD) include port wine stain, hemangioma, hypertrichosis, deviation of the gluteal furrow, lipoma, dimple, dermal sinus and acrochordon (skin tag). Dorsal accessory breast, although a rare entity, but whenever present should alert the clinician regarding the possibility of an underlying OSD. Therefore, dorsal accessory breast can also be considered as a marker of OSD.

References: 1) Guggisberg D, Hadj-Rabia S, Viney C, Bodemer C, Brunelle F, Zerah M, et al. Skin markers of occult spinal dysraphism in children: A review of 54 cases. Arch Dermatol 2004;140:1109-15. 2) Gupta VK, Kapoor I, Punia RS, Attri AK. Dorsal ectopic breast in a case of spinal dysraphism: A rare entity. Neurol India 2015;63:392-4