Parasitic rachipagus associated with complex spinal dysraphism: A case report

Background: Rachipagus is an exceptionally rare form of parasitic conjoined twinning characterized by dorsal fusion along the vertebral column and is frequently associated with spinal dysraphism. The coexistence of complex dysraphic anomalies and mature teratomatous differentiation is exceedingly uncommon and may complicate the distinction between parasitic rachipagus and mature teratoma. We report a rare case highlighting the diagnostic challenge and surgical management of this unusual entity. Case Description: An 8-month-old girl presented with a progressively enlarging congenital midline dorsal mass containing paired rudimentary limb-like appendages. Neurological examination was normal. Computed tomography demonstrated thoracolumbar spinal dysraphism, while magnetic resonance imaging revealed lipomyelomeningocele, type II split cord malformation (diastematomyelia), and tethered cord. Complete excision of the parasitic mass with surgical repair of the associated spinal dysraphism was successfully performed. Histopathological examination demonstrated mature adipose, fibrous, cartilaginous, and osseous tissues consistent with mature teratomatous differentiation. However, the characteristic clinical morphology, radiological findings, and intraoperative findings supported the diagnosis of parasitic rachipagus. The postoperative course was complicated by wound dehiscence requiring revision surgery. At 1-year follow-up, the patient remained neurologically intact with preserved bladder and bowel function. Conclusion: This case expands the limited literature on parasitic rachipagus associated with complex spinal dysraphism. Mature teratomatous differentiation does not exclude the diagnosis of parasitic rachipagus, which should be established through integration of clinical, radiological, intraoperative, and histopathological findings rather than histopathology alone. Complete excision combined with appropriate neurosurgical management can achieve favorable long-term outcomes.