Lower Gastrointestinal Bleeding Secondary to Appendiceal Mucinous Neoplasm: A Report of Two Cases and a Review of the Literature

Abstract

Appendicular mucinous neoplasms, constituting less than 1% of gastrointestinal tract neoplasms, are heterogeneous entities. They may be asymptomatic, discovered incidentally, or present as large tumors due to mucin accumulation. The lack of standardized treatment complicates management. Imaging studies, particularly CT scans, are crucial for diagnosis and follow-up. This case report presents two clinical cases of women in their sixth and seventh decades of life with a history of lower gastrointestinal bleeding, mild anemia in laboratory studies, and incomplete colonoscopies. The diagnosis, confirmed through CT scans, led to the decision for surgical intervention in both cases, involving laparoscopic right hemicolectomy with ileotransverse anastomosis. Subsequently, histopathological reports confirmed the diagnosis of high-grade appendicular mucinous neoplasms, and a follow-up plan was established with imaging studies every six months with no recurrence at two years. Over 50% of appendicular tumors are mucinous neoplasms originating from low-grade mucinous neoplasms. Given the low lymph node invasion (2%), appendectomy may suffice if the entire tumor is excised. Extensive resections or right hemicolectomy are reserved for larger tumors or high-grade neoplasms to minimize local recurrence risk. Mucinous neoplasms with acellular mucin and peritoneal invasion may require cytoreduction or right hemicolectomy, while those with mucinous epithelium may need hyperthermic intraperitoneal chemotherapy (HIPEC) due to the risk of local recurrence, worsened by the presence of extra appendiceal epithelial cells. Disease-free and overall survival depend on treatment and initial lesion characterization. A five-year survival rate of 86% is reported for low-grade mucinous neoplasms. Follow-up approaches lack an ideal standard, generally involving physical examinations and imaging studies every six months to one year during the first six years.

Keywords: appendectomy; appendicular mucinous neoplasms; lower gastrointestinal bleeding; pseudomyxoma peritonei; right hemicolectomy.

Figure 1. Computed tomography scan

(A) Coronal section: The yellow arrow indicates at the base of the appendix an image with a soft tissue density of 25 Hounsfield units (HU). However, it is in close contact with some loops of the distal ileum, and its proximal portion is immersed in the cecum. This lesion has regular, well-defined borders. (B) Axial section: A neoplasm with dimensions of 11.4 x 3.7 x 3.45 cm does not show enhancement after the administration of the contrast medium without demonstrating streaking of adjacent fat or loss of the fat plane.

Figure 2. Specimen of right hemicolectomy secondary to mucinous neoplasia of the appendix. Yellow arrows indicate a solid, soft consistency mass with irregularly calcified walls and a slight extension into the cecum, measuring 6.5 x 5.3 x 5 cm.

Figure 3. Computed tomography scan

(A) Coronal section: The yellow arrow shows a homogeneous cystic-appearing lesion with regular borders and irregular calcification of the walls at the appendicular base, extending to the cecum and terminal ileum without distant activity. (B) Axial section: A mucinous cystic neoplasm at the appendicular base measuring 13.2 x 6.4 x 4.4 cm with regular borders and calcified walls, without evidence of invasion into mesocolonic lymph nodes is seen.

Figure 4. Intraoperative findings

The yellow arrow points to an appendicular mucinous neoplasm with a firm consistency, not adhered to deep planes, and without invasion of other structures.