Un raro caso di mesotelioma multicistico del peritoneo associato ad aumento di CA 125 e CA 19.9 nel siero

Markedly increased CA 125 and CA 19.9 concentrations in serum are considered specific enough to reliably identify malignant cancers (ovarian and gastrointestinal tumours, respectively), although a consistent body of literature has reported marker elevations in several benign conditions. Here we report the case of a woman in post-menopausal status, with a previous history of hysterectomy, presenting with a 12-cm pelvic mass at sonography and serum CA 125 and CA 19.9 concentrations >400 kU/L. One month after initial presentation, she underwent surgical evaluation for laparoscopy, repeating marker determinations. Concentrations of CA 125 and CA 19.9 were still elevated, but decreased if compared with the previous data (~200 kU/L). Magnetic resonance imaging characterized a multicystic mass in the mesentery, allowing to hypothesize a benign multicystic mesothelioma of the peritoneum (BMMP). The laparoscopy revealed multiple cysts, some of them resulting in colliquation, associated to ascites. Histological examination of biopsy specimens confirmed BMMP as composed of multiple, thin-walled, irregularly spaced cysts lined by flattened and cuboidal mesothelial cells. The cystic colliquation was though as the main cause for decrease in marker concentrations. To our knowledge, this is the first case of BMMP associated with significantly increased concentrations of CA 125 and CA 19.9 and their decrease before any surgical treatment.