Anterolateral hip pain • no specific injury • Dx?

One case report described a patient with acute promyelocytic leukemia who was treated with all-transretinoic acid, daunomycin, cytarabine, and a short course of dexamethasone, and was diagnosed with AVN 2 years after the cessation of chemotherapy.⁶ This demonstrates that steroid use does not need to be recent to have a contributory effect.

Did leukemic burden play a role?

We also considered whether the patient’s leukemic burden contributed to his osteonecrosis. Leukemia and its therapy regimens have been reported to cause cerebrovascular complications,⁷ so it would be logical to postulate that they might also pose a risk to the vasculature of the femoral head. One case report describes hip pain and AVN as the initial manifestation of chronic myeloid leukemia (CML).⁸ But CML is more often associated with a severely increased white blood cell (WBC) count than is ALL, and our patient’s WBC count was in the expected range for a patient in the maintenance phase of chemotherapy, making leukemic burden a less likely culprit.

Know your patient’s history

Our patient had received an initial dose of approximately 120 mg/d prednisone alone during the first 28 days of his induction therapy for ALL. In addition, he received dexamethasone maintenance therapy, which can accumulate to >140 mg/m² over the course of therapy.⁹ This information was ultimately integral to his diagnosis and treatment.

Our patient was referred to Orthopedics. He underwent therapy with alendronate and did not require surgical intervention.

THE TAKEAWAY

This case illustrates the importance of obtaining a thorough medical history, including previous drug exposures, as a means to raise or lower one’s index of suspicion appropriately.

CORRESPONDENCE
Patrick Basile, 7124 Bristol Boulevard, Edina, MN 55435; basilepm@gmail.com.