[Solitary hypermetabolic bone focus in the initial extension study of a prostate carcinoma].

56 year old male who was diagnosed of Prostatic Neoplasm by transrectal biopsy after elevated PSA level was found by chance in a routine control. The initial extension study with abdominal and pelvic CT did not show significant radiological abnormalities. This was followed by a whole body bone scintigraphy with 99mTc-MDP that showed a solitary hypermetabolic lesion within skull. A SPECT study placed this lesion at the left occipital region. An MRI and a CT head scan were carried out to characterize the isotopic lesion, finding no bone abnormalities to justify the mentioned uptake. Given the absence of a radiological benign diagnosis, a further FDG-PET scan was carried out which did not show either increased glycolytic activity at the left occipital region, or in the prostatic gland. In order to guide the biopsy, a CT head scan was repeated which showed what appeared to be an incipient blastic lesion in the scale of the left occipital bone, establishing the differential diagnosis between a metastasis and a benign process. The anatomopathologic analysis of the bone tissue describes a necrotic process without inflammatory reaction (osteonecrosis).