Endocrine Abstracts

Introduction: Isolated bone metastasis of endometrium carcinoma is rare; but if it occurs, pelvis and vertebrae are involved mostly. Co-existence of undiagnosed Paget’s disease in a patient with malignancy causes major problems in differential diagnosis.

Case: A 77 year-old woman was admitted to our hospital with severe pelvic pain. She had been diagnosed with inoperable endometrium adenocarcinoma for over a year. Metastatic bone disease was suspected because of pain localized to pelvic region. Sacroiliac graphy and computed tomography (CT) indicated lytic lesions on sacrum, pubic ischiadicum and L5 vertebra. Increased uptake was evident in bone scintigram (Tc99). These lesions were reported as metastatic bone involvement. However, Paget’s disease was also considered in differential diagnosis. In (18)F-fluorodeoxyglucose positron emission tomography/CT [(18)F-FDG PET/CT], osteolytic and osteosclerotic lesion areas showed heterogenous FDG uptake in early (SUV_max:7.4) and late images (SUV_max:8.7), also fused images showed moderate FDG uptake on osteosclerotic lesions (SUV_max:3.7) which may be compatible with Paget’s disease. She was referred to Endocrinology Department with a suspect of Paget’s disease. Bone biopsy which was performed to exclude metastatic carcinoma revealed osteoblastic and osteoclastic activity in trabecular bone attributable to Paget’s disease and no focus of tumor infiltration was evident. Laboratory evaluations were as follows: BUN:24 mg/dl (n: 8–22 mg/dl), creatinine: 2.3 mg/dl (n: 0.7–1.4 mg/dl), serum corrected calcium: 9.6 mg/dl, PTH: 80 pg/ml (n: 15–65 pg/ml), β-CTX: 1.2 ng/ml (<1 ng/ml) ALP: 120 U/l (n: 35–105 U/l) Calcitonin (s.c.) was applied to control the disease as the patient’s glomerular filtration rate was 24.3 ml/min per 1.73 m².

Conclusion: Our patient had active disease and showed low-moderate uptake (lower than expected in malignant disease). If osteoblastic and osteoclastic activity of Paget’s disease is associated with increased glycolysis and glucose use, it could cause false-positive uptake of (18F)FDG in PET studies. Paget’s disease should be considered in differential diagnosis of positive bone scintigraphy finding during screening for bone metastasis.