Giant Appendiceal Mucocele with High Grade Mucinous Neoplasm-Case Report and Review of the Literature

Abstract

Appendiceal mucocele is a rare entity first described by Carl von Rokitansky, characterized by cystic dilatation of the appendiceal lumen due to obstruction, epithelial proliferation or inflammation and accumulation of mucoid material. The cause can be either neoplastic or non-neoplastic. Patients with appendiceal mucocele can be asymptomatic or present with right lower quadrant pain which may mimic acute appendicitis. We present the case of a 68-year-old male, who presented to the Emergency Room with a two-day history of right lower quadrant pain, nausea, vomiting and loss of appetite. Abdominal examination revealed tenderness over the Mc Burney point with localized guarding and laboratory results showed leukocytosis with neutrophilia. The abdominal computed tomography revealed a cystic dilated appendix, with a length of 130 mm and a diameter of 75 mm, situated ascending retrocecal and associating peri-appendicular inflammatory changes. The patient underwent right hemicolectomy with side-to-side ileo-colonic anastomosis, due to a wide intraluminal communication between the appendix and the cecum and the inflammation of both structures. Histopathological examination showed both high-grade and low-grade appendiceal mucinous neoplasm.

Keywords: appendicitis; high grade dysplasia; mucinous neoplasm; mucocele; right hemicolectomy.

Figure 1

The CT findings on admission—contrast enhanced CT, venous phase, multiplanar reconstruction—coronal, axial and sagital (a–c): (a) increased size of the appendix (red arrow) and inflammatory changes in the peri-appendicular space with fat stranding (orange arrow); (b) fluid content and air inclusions in the enlarged appendicular lumen (red arrow), peri-appendicular fat stranding (orange arrow); (c) thickening of the appendix walls predominantly at the base (orange arrow) and ascending retrocecal positioning of the appendix (cecum-blue arrow, appendix-red arrow).

Figure 2

The CT findings 3 months before admission—venous phase CT: increased size of the appendix (red arrow) and the absence of peri-appendicular and pericecal inflammatory changes (orange arrow).

Figure 3

Macroscopic aspects of the harvested specimen.

Figure 4

Microscopic aspects of the appendicular mucinous neoplasm: (a) appendicular wall with mucinous proliferation (arrow) and atrophy of the lymphoid tissue (arrowhead), 5×; (b) flat and filiform pattern of the proliferation (arrow), with endoluminal extravasated mucin (arrowhead), 5×; (c) filiform and villous pattern of the proliferation (arrow), 5×; (d) complex filiform and glandular pattern, with both low-grade (arrow) and high-grade atypical epithelial dysplasia (arrowhead), 20×; (e) low-grade atypia (arrow) and extravasated mucin (arrowhead), 10×; (f) high-grade atypical epithelial dysplasia (arrow), 20×.

Figure 5

Microscopic aspects in Hematoxylin-Eosin staining, 5×: (a) colonic wall (arrow); (b,c) lymph node with catarrh (arrow), histiocytosis (arrowhead), vascular hyperemia (twisted arrow) and reactive follicular hyperplasia (triangle).