F18-FDG PET/CT in retroperitoneal desmoplastic small round blue cell tumour occurring in a patient with in situ breast carcinoma.

To cite: Piciu D, Barbus E, Pestean C, et al. BMJ Case Rep Published online: [please include Day Month Year] doi:10.1136/bcr-2015212659 DESCRIPTION We present a case of a 58-year-old woman, diagnosed with low-grade in situ ductal breast carcinoma (3 mm), who underwent conservative mastectomy. She was admitted 7 months later for diffuse abdominal and bone pain, weight loss, and an enlargement of the abdomen, asthenia, cough and nausea. Breast imaging and specific clinical examinations were negative for recurrence of malignant breast disease, but chest and abdominal CT revealed multiple tumour masses in the mediastinum, and multiple lytic lesions in the sternum, ribs, right humerus and pathological para-aortic lymph nodes (figure 1). The common tumour markers for breast, ovaries, lung, colon, pancreas and neuroendocrine tumours were normal and, apart from a mild anaemia, no other significant serological changes were found. The clinician requested an F18-fludeoxyglucose positron emission tomography (FDG PET)/CT examination in order to define the extent of the disease and to find the primary site. The result showed a very high and extensive FDG uptake in the retroperitoneal area due to a 27 cm tumour involving both ureters, with secondary obstruction (figure 2A); there was also high pathological FDG activity in the bilateral cervical lymph nodes, mediastinum and inguinal lymph nodes; there were multiple bone lesions in the right humerus, sternum, ribs, pelvic bones and left femur (figure 2B). The diagnosis was possible metachronous lymphoma or Figure 1 Axial abdominal CT section, presenting pathological para-aortic tumour mass.