Nontraumatic avulsion of the lesser trochanter: a pathognomonic sign of metastatic disease?

Isolated avulsion fractures of the lesser trochanter resulting from trauma are most commonly seen in adolescent athletes and are rare in adults. Standard therapy is nonsurgical with bedrest and immobilization of the leg. However, when this lesion is seen in the adult without significant trauma, it should be regarded as secondary to metastatic neoplasm until proven otherwise. Treatment should be surgical with prophylactic internal fixation of the hip to help prevent the commonly associated subtrochanteric pathologic fracture. In a patient without a known primary malignancy, biopsy should be carried out before therapy. We describe four patients with isolated avulsion fracture of the lesser trochanter due to metastatic carcinoma. Radiologists should be aware of this lesion because its presence has a decisive effect on therapy.