Benign uterine uptake of FDG: a case report and review of literature.

We observed very high uterine [F]-fluorodeoxyglucose (FDG) uptake on positron emission tomography (PET) in what proved to be a benign uterine leiomyoma. Although clinically apparent in 25% of women and prevalent in up to 77%, this phenomenon is only incidentally described. Here we present a case of a 49-year-old woman. Our patient underwent an FDG-PET/CT for follow-up of an infectious focus on the lower back. Apart from a metabolically active lymph node and bone marrow, it revealed a ~9.6 cm large, inhomogeneous but sharply demarcated FDG-avid lesion in the posterior uterine wall (figure 1). The lesion was ultrasonographically a typical large leiomyoma. An abdominal hysterectomy was performed for lumbago and anaemia due to menometrorrhagia. Histopathological examination revealed an enlarged uterus with an intramural leiomyoma of 7.8 cm in diameter and multiple small subserosal leiomyomas, the size below the resolution of the PET/CT scanner. Microscopy showed the typical image of a leiomyoma, without signs of necrosis, haemorrhage, atypia or inflammation. There was no cervical atypia and the endometrium was thin (<1 mm) and showed some changes corresponding to progestagen suppletion. In search of an explanation for the high FDG uptake, sections of the anterior – on PET normal – uterine myometrium were compared with sections of the leiomyoma. Immunohistochemical staining of markers for proliferation, inflammation, hypoxia, apoptosis, vascularity, glucose metabolism and glycogen content was quantified. This quantification demonstrated a slight increase in proliferation and glycogen content. Incidentally found leiomyomas are occasionally reported to have elevated FDG uptake (standardised uptake value (SUV) l e t t e r t o t h e e d i t or