(99m)Tc-MDP uptake in soft-tissue osteosarcoma in a dog.

A 6-year-old, female Alaskan malamute domestic dog was presented for a bone scintigraphy with a soft tissue tumour of 4 months duration. The tumour at the time of scintigraphic examination was 10 cm in diameter and was localized in the lateral line on the right chest along the 11th rib. Pathologic diagnosis based upon fine needle biopsy was osteogenic sarcoma. The aim of the scan was to assess the bone involvement with eventual metastases prior to the operation. Bone scanning was performed in anterior and posterior projections using a dual-head gammacamera Multispect-2 (Siemens, Erlangen, Germany), 3 hours post-injection of 99mTc-MDP (OBRI-Polatom, Otwock, Poland). The bone scan (Figure 1) revealed an accumulation of 99mTc-MDP not only as the linear foci in the 10th and 12th adjacent ribs, but also in the primary tumour (arrow), more pronounced at its base. The metastases were confirmed in situ during the operation, when the ribs were removed.