title: Lytic lesions of the femoral neck in rheumatoid arthritis simulating pigmented villonodular synovitis or malignancy.
abstract: Large lytic lesions, relatively asymptomatic, involving the femoral neck and the base of the head are described in two patients suffering from a classical seropositive rheumatoid arthritis. Histological examination failed to reveal signs of malignancy, infection or pigmented villonodular synovitis. There were no rheumatoid nodules but a chronic hypertrophic villous synovitis was found. Rheumatoid synovium may invade the superior extremity of the femur; this fact is important in the differential diagnosis of destructive lesions of the femoral neck in RA.
mesh_terms: D000368:Aged; D001172:Arthritis, Rheumatoid / Q000175:diagnosis / Q000473:pathology*; D003937:Diagnosis, Differential; D005260:Female; D005266:Femoral Neoplasms; D005272:Femur Neck / Q000473:pathology*; D006621:Hip Joint / Q000473:pathology; D006801:Humans; D008875:Middle Aged; D010014:Osteolysis / Q000473:pathology; D013583:Synovial Membrane / Q000473:pathology*; D013585:Synovitis / Q000150:complications / Q000175:diagnosis*; D013586:Synovitis, Pigmented Villonodular / Q000175:diagnosis* / Q000473:pathology