A Rare Case of Primary Peritoneal Carcinoma With Large Bowel Metastasis

Primary serous peritoneal carcinoma (PPC) is a rare malignancy often presenting with a significant disease burden and a poor prognosis. A 65-year-old female was seen in the surgical outpatient clinic with a two-month history of weight loss, altered bowel habits and a CT scan characterizing a heterogenous right paracolic gutter mass and suspicious liver lesions. At colonoscopy, a prominent appendiceal orifice was biopsied to be poorly differentiated carcinoma favouring gynaecological tract origin. The patient was admitted with an acute small bowel obstruction secondary to progression of metastases and underwent neoadjuvant chemotherapy with a near complete response on repeat staging. A debulking hysterectomy, bilateral salpingo-oophorectomy, pelvic peritonectomy and small bowel nodule excision were performed. The diagnosis of PPC was confirmed when no malignancy was found in the pelvic organs. The presence of intraluminal colonic metastasis with PPC is exceedingly rare with this being only the third such case in the literature.