Femoral Neck Bone Marrow Edema During Isotretinoin Therapy: A Case Report.

Isotretinoin is a widely prescribed retinoid for severe acne, with musculoskeletal adverse effects such-particularly sacroiliitis-well documented in the literature. However, isolated femoral neck bone marrow edema has not previously been reported. We describe a 27-yr-old female physical medicine and rehabilitation resident who developed acute right hip pain while receiving isotretinoin therapy. Pelvic radiography and sacroiliac magnetic resonance imaging, obtained independently by the patient, were normal, but as symptoms progressed, she was examined by a physiatrist, and careful clinical assessment with accurate localization of pain prompted a dedicated hip magnetic resonance imaging, which revealed isolated femoral neck bone marrow edema. Laboratory evaluation excluded infection, inflammatory arthritis, and metabolic bone disease. Isotretinoin was discontinued, and the patient was treated conservatively with weight-bearing restriction, vitamin D and calcium supplementation, and analgesics, leading to complete clinical and radiologic resolution within 3 mos. This case represents the first report of isolated femoral neck bone marrow edema linked to isotretinoin therapy and underscores the importance of early recognition, as timely diagnosis through precise clinical assessment and targeted imaging enables unloading strategies that can prevent progression to stress fracture and ensure favorable outcomes in isotretinoin-treated patients presenting with hip pain.