Synchronous multiple primary malignant neoplasms: a case report of malignant peritoneal mesothelioma and neuroendocrine rectal tumor

We report a rare case of synchronous malignant peritoneal mesothelioma of the biphasic histological type and neuroendocrine tumor (NET) of the rectum without history of asbestos exposure. During 2 years since manifestation of the disease the patient underwent 3 cytoreductive surgeries (CRS): removal of the tumor of the sigmoid mesentery, resection of the rectosigmoid junction completeness of cytoreduction (CC) 0 (2017), omentectomy and partial parietal peritonectomy CC-0 (2017), atypical resection of S2, S4, S5 liver, the removal of the abdominal tumor with left-sided en-block hemicolectomy, partial parietal peritonectomy, argon-plasma coagulation of tumor foci on the mesentery of the small intestine CC-2 (2018) and Transanal Minimally Invasive Surgery-removal of neuroendocrine rectal tumor (2017). The patient underwent hyperthermic intraperitoneal chemotherapy (HIPEC) twice (during 2nd and 3rd CRS). Different regimens of HIPEC were performed: cisplatin + doxorubicin (2017) and metamycin C (2018). The patient received 4 courses of adjuvant chemotherapy with cisplatin plus pemetrexed in 2017 and 3 courses of the chemotherapy with gemcitabine and carboplatin plus bevacizumab in 2018. The patient survived 21 months after the detection of malignant peritoneal mesothelioma in 2017 and died 4 months after the last cytoreductive surgery from the progression of the disease. Histological subtype of MPMP remains important factor in the prognosis of the disease even on the early stages though patient had received the most aggressive variant of special treatment. Minimally invasive treatment tactics of NET demonstrated clinical effectiveness. &nbsp