University of Massachusetts Medical Center Worcester, MA
Kristen L. Moulton, BA, DO1, Emily Weng, DO, BS2, Lidia Spaho, MD, BS1, Jean Marie Houghton, MD, PhD1; 1University of Massachusetts Medical Center, Worcester, MA; 2University of Massachusetts Medical School, Worcester, MA
Introduction: Pseudomyxoma peritonei (PMP) is a radiological finding which involves progressive growth of mucin within the abdomen and pelvis, often originating from an appendiceal lesion. The accumulation of mucinous fluid ranges in severity. Disseminated peritoneal adenomucinosis follows a more indolent course with acellular benign growth. In contrast, peritoneal mucinous carcinomatosis (PMCA) is more aggressive as tumor cells invade the peritoneum and compress vital organs. Initial complaints for both are often non-specific, including vague abdominal pain, distention, or firmness.
Methods: A 39-year-old male without significant medical history presented to an urgent gastroenterology (GI) clinic with 3 months of debilitating abdominal pain and firmness, associated with decreased appetite and unintentional weight loss. He had previously presented to his primary care mid-level provider on two separate occasions, where workup with abdominal x-ray and right upper quadrant ultrasound was unremarkable. Physical exam in the GI clinic was concerning for a firm abdomen suggestive of omental caking. An urgent CT abdomen pelvis showed an appendiceal mass, moderate ascites, and extensive peritoneal carcinomatosis throughout the omentum, perihepatic, and perisplenic regions (Figures 1, 2). Ultrasound-guided biopsy of the omentum revealed mucinous adenocarcinoma of appendiceal origin. Colonoscopy was significant for a large fungating mass in the cecum (Figure 3); biopsy showed tubulovillous adenoma with focal high-grade dysplasia. The patient underwent cytoreductive surgery, which included partial splenectomy, right and transverse colectomy, appendiceal mass resection, small bowel resection, and total omentectomy. He received hyperthermic intraperitoneal chemotherapy with Mitomycin C as well as systemic pembrolizumab immunotherapy. Discussion: While the incidence is low, it is important for providers to consider PMP and carcinomatosis when addressing complaints of diffuse abdominal firmness and pain with movement. This case highlights the importance of the physical exam and the possible medical knowledge gaps in primary care mid-level providers. Prompt GI referral is imperative in cases where the differential diagnosis is unknown. Patients with PMP and PMCA often experience months of debilitating symptoms prior to an appropriate diagnosis. Heightened clinical awareness of this illness can accelerate time to diagnosis and initiation of treatment.
Figure 1: CT abdomen pelvis revealed expansion of the lumen at the distal aspect of the appendix, consistent with appendiceal carcinoma.
Figure 2: CT abdomen pelvis showed extensive peritoneal carcinomatosis with thickening of the omentum, particularly notable in the perihepatic region.
Figure 3: Colonoscopy revealed a non-obstructive fungating mass. Pathology was consistent with a tubulovillous adenoma with focal high-grade dysplasia.
Disclosures: Kristen Moulton indicated no relevant financial relationships. Emily Weng indicated no relevant financial relationships. Lidia Spaho indicated no relevant financial relationships. Jean Marie Houghton indicated no relevant financial relationships.