[Metastatic prostate cancer associated with low levels of prostate-specific antigen]

A case was reported of a 67-year-old patient with right buttock pain radiating to the thighs and affecting his bipedalism and gait. With four months into the disease and a weight loss of 15 kilos, the patient underwent imaging tests which showed sacrum infiltration. The biopsy diagnosis was injury of bone tissue infiltrated by poorly differentiated adenocarcinoma. The rectal examination performed as part of the clinical urologic examination revealed a nodular lesion of less than one centimeter, despite the level of prostate-specific antigen (total PSA: 4.62 mg/dL). The prostate biopsy evidenced a poorly differentiated adenocarcinoma (Gleason score: 8). The bone scan showed active lesions associated with metastasis in the middle third of the right clavicle, the sacrum and the right pubic region.