PET-CT demonstration of extensive muscle metastases from breast cancer

Distant hematogenous spread of metastases to muscle is a distinctly uncommon manifestation of malignancy. With respect to breast cancer, occasional reports of solitary muscle metastases have appeared, although diffuse metastases to muscle is distinctly uncommon. We report an 83-year-old woman with breast cancer previously diagnosed and treated 27 years earlier who presented with decreased vision and extraocular muscle palsies. MRI showed nodular thickening of the orbital muscles and biopsy confirmed metastasis from breast cancer. Subsequent PET-CT demonstrated extensive foci of increased F-18 fluorodeoxyglucose (FDG) uptake in muscle and bones throughout the body consistent with metastases. Of interest, the patient had undergone bilateral hip replacement for degenerative disease I year previously; pathologic review of the previously resected femoral bone sample revealed no evidence of metastasis at that time.