Incidental diagnosis of primary appendiceal signet-ring cell adenocarcinoma after appendectomy for acute appendicitis: a case report

Abstract

Introduction: Appendiceal signet-ring cell adenocarcinoma (ASCA) is rare and more aggressive in malignant appendiceal neoplasms. The presentation can be appendicitis, which is lack of specific symptom and makes early diagnosis difficult. There is no effective surveillance. Prognosis largely relies on timely detection. We report a case of ASCA incidentally diagnosed through pathological examination after appendectomy for appendicitis.

Case presentation: The patient presented to our department with a progressive right lower quadrant abdominal pain lasting for 3 days. Physical examination revealed rigidity, tenderness, and rebound tenderness on the right lower quadrant. A computed tomography scan showed a thickened, inflamed appendix with peri-appendiceal fat stranding without noticeable appendiceal mass at initial evaluation. The diagnosis was considered acute appendicitis, and an appendectomy was performed. The appendix was inflamed, gangrenous and perforated, and no mass was found during the surgery. Surgical specimen was sent for physiological examination, which incidentally detected signet-ring cell in H&E staining. And immunohistochemistry confirmed the diagnosis of ASCA with small amount of neuroendocrine neoplasms.

Conclusion: Early diagnosis of ASCA can incidentally be made on pathological specimen following appendectomy for appendicitis. A routine pathological examination should be emphasized, and appendectomy may not be the endpoint of the treatment. Hemicolectomy and adjuvant therapy might ensue upon the diagnosis of appendiceal neoplasm. The poor prognosis of ASCA makes a timely diagnosis significant. Basic research is promising to unravel the molecular mechanisms of pathogenesis, finding typical tumor markers for screening and novel effective therapies for advanced cases.

Keywords: acute appendicitis; appendectomy; appendiceal neoplasms; signet-ring cell adenocarcinoma; treatment.

Figure 1

Imaging findings of CT scan and laparoscopy. The appendix was enlarged with peri-appendiceal fat stranding and fluid (arrow ⇦) around it (A); laparoscopy showed purulence (arrow ⇦) around the area of the appendix (B).

Figure 2

H&E staining and immunohistochemistry results. H&E staining (×10 and ×40 magnification) showed typical signet-ring cell morphology; immunohistochemical analysis demonstrated that CK and CDX-2 (×4 magnification and ×40 magnification) were highly expressed with a high index of Ki-67 and a small amount staining of CgA, SYN, and CD56 (×4 magnification and ×40 magnification).

Figure 3

Algorithm for suggested management to incidental diagnosis of ASCA following appendectomy for appendicitis.