Involvement of the musculoskeletal system by primary or metastatic malignant neoplasms mimicking common orthopaedic conditions is well recognized. The diagnosis may be delayed in the absence of radiographic abnormalities. Twenty-five percent of lymphoma cases have skeletal involvement, and they can affect both bone and soft tissue. Lymphoma is sometimes discovered by means of routine histologic examination of tissue collected at the time of orthopaedic surgery. To the best of our knowledge, this is the first report of lymphoma occurring at the site of prior shoulder surgery and mimicking an infection.