Low-grade intraosseous osteosarcoma is an uncommon and well-differentiated
osteosarcoma with a good prognosis. We report a proximal tibial low-grade i
ntraosseous osteosarcoma with a prominent intratumoral lymphoid infiltrate,
which led to an initial diagnosis of probable malignant lymphoma. The impo
rtance of this infiltrate, which exhibited reactive features on flow cytome
tric studies, is not known. Our patient is free of tumor 1 year after limb
salvage surgery, without hematologic or lymphoid abnormalities.