Osteosarcoma of the breast—an unusual presentation

Abstract

Cystosarcoma phyllodes is an uncommon primary breast malignancy which undergoes osteosarcomatous differentiation in a small subgroup of patients. Uptake of 99m technetium methylene diphosphonate (99mTcMDP) is known to occur within pulmonary, lymph node and soft tissue metastases arising from osteosarcomas of bone and is related to the presence of osteoid within these tumours. Uptake of 99mTcMDP has also been reported from pulmonary metastasis arising fromosteosarcomasof the breast. Similar uptake would be expected from osteoid elements of the breast sarcoma itself, but this has not been previously documented. We present a case of an osteosarcoma of breast showing up as intense uptake on bone scintigraphy performed for unrelated joint pains. The hot spot seen projected over the right upper chest could not be explained satisfactorily at the time of the study and was thought to represent an artefact. A few weeks later, the patient presented with a breast lump, which was subsequently diagnosed as an osteosarcoma in phyllodes tumour. Retrospectively, the unexplained hot spot on bone scintigraphy corresponded to the site of tumour in the right breast.