Brown Tumor as an Index Presentation of Severe Vitamin D Deficiency in a Teenage Girl.

Brown tumor is a non-neoplastic fibro-cystic expansile bone lesion caused by parathyroid hormone excess. It has been commonly described in patients with primary hyperparathyroidism and secondary hyperparathyroidism due to chronic kidney disease. However, it is very rare to encounter a brown tumor in the setting of nutritional vitamin D deficiency. We describe the case of a 16-year-old girl who presented with brown tumor-like lytic lesion of femur caused by severe longstanding vitamin D deficiency. Treatment with elemental calcium and cholecalciferol resulted in correction of hyperparathyroid state, with the resultant disappearance of the bony lesion and remarkable symptomatic improvement. Unnecessary orthopaedic intervention may be avoided using a high index of suspicion and performing targeted investigations in such cases.