I liopectineal bursitis (IB) is a poorly recognized cause of hip pain, which could have serious complications caused by compression of adjacent structures. It can occur in the setting of trauma or in association with arthritis, as in ankylosing spondylitis (AS). 1-3 A 43-year-old man with AS, characterized by axial involvement and hip arthritis, under treatment with adalimumab 40 mg every 2 weeks, in remission, presented with pain, swelling, and numbness of the proximal region of the right thigh, after a physical effort. Physical examination showed enlargement of the right thigh, without any other symptoms (Fig. 1). Ultrasound revealed a lesion suggestive of hematoma, but magnetic resonance imaging demonstrated right IB with compression of the right femoral vein. This is compatible with the diagnosis of noninfectious IB in the context of physical effort (Figs. 2A, B). Patient was treated with nonsteroidal anti-inflammatory drugs with complete resolution.The IB is mostly associated with rheumatoid arthritis, but its association with AS is poorly reported. 4 The recurrent inflammation at the hip joint causes weakness of the anterior capsule allowing communication between the joint and bursa, which occurs in almost 10% to 15% of the cases. 5 Our patient's case history suggests a possible traumatic cause, but an association with hip synovitis and secondary osteoarthritis cannot be excluded, despite that no communication with hip joint was identified. Compression of the femoral vein was observed in our patient and despite neurologic findings was not detected in physical examination; probably, the femoral nerve suffered some pressure given the numbness referred.In conclusion, unilateral leg swelling, inguinal mass, or groin tenderness on physical examination, in patients with trauma or previous history of hip joint disease, should raise clinical suspicion of IB, because awareness of this entity may lead to a correct diagnosis and adequate treatment.