Melorheostosis: A Rare Case Report with Pelvic and Lumbar Involvement.

Introduction: Melorheostosis is an extremely rare, non-hereditary bone disorder characterized by its distinctive radiographic feature of flowing hyperostosis, reminiscent of dripping candle wax, typically appearing unilaterally in long bones. Initially proposed by Leri and Joanny in 1922, the exact cause remains largely speculative, and treatment is primarily symptomatic. This condition predominantly affects a single limb, with a higher incidence in the lower extremities, while axial skeletal involvement is uncommon. Case Report: We present a severe melorheostosis affecting the left lower limb, accompanied by ipsilateral pelvic involvement and soft tissue abnormalities in the lumbar region, while the contralateral side remained unaffected. Radiographic imaging revealed substantial heterotopic ossification and dense hyperostosis in the periarticular soft tissues of nearly all bones in the affected limb, from the femur to the distal phalanges of the toes. Patient's physical examination identified functional scoliosis, joint rigidity and distortion, and significant edema and deformity of the left extremities. In addition, a soft tissue mass over the L3 region, later identified as an arteriovenous malformation through fine needle aspiration cytology, was observed. The right side was entirely normal. Conclusion: This case details a unique presentation of severe monomelic melorheostosis in a 28-year-old Indian woman, involving the left lower limb, pelvis, and lumbar soft tissues. Radiographic and computed tomography imaging revealed extensive cortical hyperostosis with associated soft tissue ossifications. We discuss the clinical presentation, diagnostic approach, and management of this intricate condition, supported by illustrative imaging.