MRI features of Lyme arthritis of the hips.

Diagnosing Lyme arthritis without a history of travel to endemic regions or erythema migrans can be a challenge. Radiographic and ultrasonographic findings are nonspecific for the diagnosis of Lyme arthritis. We present the MRI features of Lyme disease of the hip in a 4-year-old boy who presented with hip pain and was found to have Lyme disease by Western blot. Our findings include bilateral hip effusions and synovial enhancement, normal bone marrow signal intensity without enhancement, minimal adjacent muscular and soft-tissue edema, and bilateral inguinal lymph nodes measuring up to 1 cm.