Unusual presentation of altered bone metabolism with long-term antiepileptic therapy: pathological fracture of neck of femur due to brown tumor at calcer.

The antiepileptic drugs are known to alter the bone metabolism and result in various range of pathological conditions (osteoporosis, osteomalacia, vitamin D deficiency, secondary hyperparathyroidism). These clinical conditions developed either due to direct effect of these therapeutic agents on bone or due to alteration in the homeostasis of other regulators of bone metabolism like serum calcium, vitamin D, and parathyroid hormone. Long-term therapy with antiepileptic agents results in higher incidence of pathological fracture, which is a consequence of either osteoporotic or osteomalasic (secondary to vitamin D deficiency) changes in bone produced by these drugs. Secondary hyperparathyroidism due to vitamin D deficiency following long-term polytherapy of antiepileptic drug ultimately leading to development of brown tumor and pathological fracture is very unusual.