Management of Solitary Osteochondroma Arising from Mammillary Process of D12 Vertebra in an 11-Year-Old Female: A Rare Case Report and Literature Review.

Introduction: Osteochondromas are benign bony lesions arising from the metaphysis of long bones, commonly arising from the distal femur, proximal tibia, and proximal humerus, with rare incidence of its presence over the flat bones such as the scapula and pelvis. The spine can be rarely affected by osteochondromas in 1-4% of all cases. The origin of osteochondroma from the mammillary process of the D12 vertebra is very rare. Hence, we are reporting this rare phenomenon. Case Report: An 11-year-old female presented with the complaints of gradually progressive swelling in the mid-back region with discomfort on lying down in the supine position. Based on clinical and radiological findings, a provisional diagnosis of osteochondroma arising from D12 vertebrae was made and planned for excisional biopsy under general anesthesia. Histopathology of the excised bone mass was consistent with osteochondroma. The patient was followed for 1 year, in which no signs of recurrence were found, and she was carrying out her activities of daily living without any discomfort. Conclusion: Osteochondroma of D12 is a rare phenomenon, but it should also be kept as a differential diagnosis while treating patients with unexplained back symptoms in a normal X-ray. Surgical excision should be kept reserved for large osteochondromas outside of the neural canal or tumors causing neural symptoms.