Sonographic Findings of Malignant Appendix Tumors in Seven Cases

Abstract

We report the sonographic features of confirmed malignant appendiceal tumors in seven cases. The histologic diagnoses of these tumors were mucinous cystadenocarcinoma (n = 2), colonic type adenocarcinoma (n = 4), and signet-ring cell carcinoma (n = 1). The 2 mucinous cystadenocarcinomas showed mucocele type, which had markedly enlarged inner luminal diameters (mean, 23 mm; range, 15-31 mm) and thick, irregular walls (mean wall thickness, 5.5 mm; range, 5-6 mm). In contrast, the 5 nonmucinous carcinomas (4 adenocarcinomas and 1 signet-ring cell carcinoma) showed nonmucocele type, which had relatively small inner luminal diameters (mean ± standard deviation [SD], 6.6 ± 4.5 mm; range, 2-15 mm) and prominent wall thickening (mean wall thickness ± SD, 6.2 ± 2.3 mm; range, 3-10 mm). Of the 5 nonmucinous tumors, only one had a discernible mass, three had thick irregular walls, two had loss of the wall layer pattern, and four had submucosal hypoechogenicity. Regardless of the histologic type, five of the seven malignant appendiceal tumors showed a severe periappendiceal fat infiltration or periappendiceal abscess, suggestive of perforation. Although the sonographic findings of the malignant appendiceal tumors were nonspecific, some of the sonographic features seen in these seven cases may help radiologists consider the possibility of underlying malignant appendiceal tumors.

Keywords: Appendix; malignant tumor; sonography.

Figure 1

A 56-year-old man with a mucinous adenocarcinoma in the appendix (Case 2).(a) A coronal computed tomography scan of the appendix shows cystic dilatation of the appendix (arrow, A) and irregular wall thickening. (b) Axial sonography of the appendix also shows cystic dilatation of the appendix and irregular wall thickening (arrow, B). (c) A low-power microphotograph shows a cystic, dilated appendix with abundant intraluminal mucin (H and E, ×10). (d) The appendiceal lumen is lined by a mixture of high-grade, pseudostratified, columnar, neoplastic epithelium and low-grade, mucinous epithelium (H and E, ×40)

Figure 2

A 79-year-old man with a nonmucinous adenocarcinoma in the appendix (Case 4). (a) An axial sonography shows an irregular, hypoechoic mass (arrow) at the appendiceal base and cecum. Loss of the wall layer pattern is also noted. (b) On gross examination, adenocarcinoma (arrow) was detected at the appendiceal base. (c) A low-power microphotograph showes tumor cells infiltrating the mucosa, submucosa, muscularis, and serosa layers and periappendiceal tissue (H and E stain, ×100). B, appendix base; C, cecum; L, lumen; M, muscle; m, mucosa; S, serosa; sm, submucosa; P, periappendiceal tissue