First Report of a Low-Grade Pseudomyxoma peritonei Originating from Gall Bladder.

Pseudomyxoma peritonei (PMP) refers to accumulation of mucinous ascites with or without neoplastic cells in the peritoneal cavity. It most commonly originates from a low or a high grade primary appendiceal mucinous neoplasm. Though adenocarcinoma of gall bladder has been reported to give rise to PMP, to the best of our knowledge, this is the first report of a PMP arising from a low grade mucinous tumour of the gall bladder. A 72-year-old patient was diagnosed with PMP 1.5 years after a cholecystectomy. After initial oral TS1 (combination of tegafur, gimeracil and oteracil) and later intraperitoneal (IP) chemotherapy with docetaxel and cisplatin, the patient was operated with the goal of tumour debulking, including removal of 5.5 L of mucinous ascites, an appendectomy, and ovariectomy. The histopathologic report showed a normal appendix and metastasis of PMP to the right ovary. After the exclusion of the 2 most common sites of origin (appendix and ovary), the specimen of the cholecystectomy was reviewed. It showed low grade mucinous tumour in the gall bladder, with immuno-histochemical markers (IHCs) suggestive of CK7, CDX2, MUC 2 positive and CK20, MUC5AC negative. MIB-1 index was 12%. The pathologic report of cytoreductive surgery performed after 7 cycles of IP chemotherapy confirmed the diagnosis of PMP originating from low grade mucinous tumour of the gall bladder. Our case report illustrates a rare disease and highlights that, though peritoneal metastasis from gall bladder cancers are known to have a poor prognosis, the peritoneal dissemination from a low grade mucinous neoplasm of gall bladder (PMP) has a significantly better prognosis due to a better disease biology and improved treatment options currently available for the treatment of PMP.