de Beer J D, Bogoch E R, Smythe H A
University of Toronto Rheumatic Disease Unit, Department of Orthopaedic Surgery, Toronto, ON, Canada.
J Rheumatol. 1990 Sep;17(9):1242-3.
A patient with HLA-B27 and rheumatoid factor positive rheumatoid arthritis presented with a painless swelling in his popliteal fossa. Clinical features were atypical for a Baker's cyst, and subsequent investigation showed this lesion to be a primary malignant lymphoma.