Pseudomyxoma Peritonei: A Case Report of a 62-Year-Old Female With Unexplained Abdominal Enlargement and Appendiceal Origin

Abstract

CASE: A 62-year-old female with a history of Type 2 Diabetes Mellitus, Obesity, Hypertension, and high-grade left breast DCIS status post simple left mastectomy and adjuvant chemotherapy. She noted abdominal enlargement and generalized tenderness on her follow-up. Abdominal ultrasonography showed trace ascites, cirrhotic liver, and splenomegaly. Magnetic resonance imaging suggested omental caking. Labs: CA125 - 31, CA15-3 - 24, CEA-72, CA19-9 - 48. Fine needle aspiration of the omental mass showed mucinous pools with linings of mucin secreting epithelium with mild atypia. Immunohistochemical staining positive for CK7 and SATB2 with nuclear atypia; Negative for CK20, CDX2, and mammaglobin. Mammography and gastrointestinal endoscopies showed no evidence of neoplasm. She underwent surgical debulking followed by hemicolectomy with omentectomy and bilateral salpingo-oophorectomy with peritoneal stripping. Pathology reported lowgrade appendiceal mucinous neoplasm with visceral peritoneal penetration (LAMN pT4a) confirming the diagnosis of Disseminated peritoneal Adenomucinosis. CA19-9, CEA, and CA125 levels trended down postoperatively. The patient is scheduled for adjuvant chemotherapy. IMPACT/DISCUSSION: PMP refers to a diffuse mucinous peritoneal involvement from various sources of mucin-producing invasive adenocarcinomas including intestines, lung, breast, pancreas, stomach, bile ducts, gallbladder, fallopian tubes, and ovaries. Histologically, it is classified into 4 types: Acellular Mucin, Disseminated Peritoneal Adenomucinosis (DPAM), Peritoneal Mucinous Carcinomatosis (PMCA), and Peritoneal Mucinous Carcinomatosis with Signet Ring cells (PMCA-S). Patients usually present with non-specific symptoms (ascites, abdominal distension, abdominal mass, diffuse abdominal pain), and evidence of PMP is an incidental finding in almost 20% of cases. There are no specific guidelines for the staging workup for PMP. American Society of Colon and Rectal Surgeons recommends the same staging workup as for colon cancer - Computed tomography of chest, abdomen, and pelvis, and a colonoscopy to detect the primary source of neoplasia. CEA, CA 19-9, and CA-125 are associated with PMP while CEA is useful for prognosis and post-treatment surveillance. Treatment strategies for PMP vary from watchful waiting to cytoreductive surgery with Hyperthermic intraperitoneal chemotherapy (HIPEC) or early postoperative intraperitoneal chemotherapy (EPIC). Recent studies support cytoreduction with peritonectomy plus HIPEC as a safe procedure suggesting improved survival rates, even in aggressive cases. CONCLUSION(S): The rarity of PMP has precluded any randomized studies and few institutions see sufficient cases to report a series of homogeneously treated patients. Treatment guidelines remain wanting.