Diseases of Vermiform Appendix

1. Diseases of Vermiform Appendix • Developmental Abnormalities • Inflammatory disorders • Parasitic infections • Neoplasms • Miscellaneous lesions

2. Diseases of the Appendix Developmental Abnormalities • Agenesis • Hypoplasia • Duplication • Malposition

3. Diseases of the Appendix Inflammatory disorders • Acute appendicitis • Specific infections: e.g. Tuberculosis Amoebiasis Actinomycosis

4. Acute appendicitis • Disease of adolescents & young adults • The most frequent surgical condition of the abdomen (6-8% lifetime risk) • Associated with luminal obstruction in 50-80% • Impacted feces / fecalith, lymphoid hyperplasia, foreign body / parasites and tumor are among the causes of obstruction • Viral infection may be related in nonobstructive cases but most are unknown

5. An autosy case of acute appendicitis with fatal complication The patient had been treated as acute gastroenteritis in the first visit with symptoms including abdominal pain, nausea/vomiting and diarrhea Septic shock developed within a few days after onset of the disease. Perforation

6. Do all cases of acute appendicitis die without appropriate treatment? The answer = No.. Simple mucocele developed after acute episode of appendicitis. -Resolution -Chronic appendicitis -Fibrotic appendix -Total destruction and disappearance mimicking agenesis Organized abscess may mimic neoplastic lesion since it can grow larger and larger.

7. Pathogenesis of appendicitis • Obstruction, any cause • Increased luminal pressure from continued mucous secretion and peristalsis • Collapsed venous drainage compromised blood supply • Ischemic injury of mucosa bacterial invasion • Gangrenous inflammation / perforation

8. Impacted fecal content is common cause of obstruction

9. Carcinoma of caecum with appendicitis as consequence

10. Parasites found in the Appendix Gnathostoma spinigerum: gross, histology & scanning electron micrograph Enterobius vermicularis Proglottid of Taenia solium

11. Parasitic tract found in the appendiceal wall in a case of eosinophilic appendicitis The parasite cannot be found ! Necrotic tissue in the tract Heavy eosinophilic infiltration around the tract

12. Duration of the course of an acute appendicitis varying from few hours to several days Hemorrhagic wall and fibrinous deposits of the wall with numerous neutrophils and red blood cells among the infiltrates fibrin -Reaction is virtually acute Inflammation beginning at mucosa with rapid extension through the wall and peritoneum. -Mucosal ulceration and progression of mural destruction can lead to perforation very soon.

13. Mucocele of Appendix-- --Definition: A gross or clinical descriptive term for dilation of the appendiceal lumen by mucus. • Non-neoplastic Mucocele: • May be caused by appendicitis, fecalith, endometriosis • Usually small size; dilated lumen about 1 cm or less • No neoplastic epithelium identified • Low-grade mucinous neoplasm of appendix (Mucinous Cystadenoma ) • Mucinous cystadenocarcinoma

14. Simple Mucocele of Appendix: Pathologic features -Evidence of appendicitis (this case) or other primary causes that lead to chronic obstruction -Mild dilatation and mucus-filled appendiceal lumen -No neoplastic epithelial cells found along the lining (Remnant mucosal glands seen around the dilated lumen along with inflammatory cells)

15. Appendiceal Tumors • AppendicealMucinous Neoplasm (neoplastic mucocele) • Low grade appendiceal mucinous neoplasm ( LAMN) Previously called ‘cystadenoma’ • Mucinous cystadenocarcinoma • Carcinoid tumor (neuroendocrine neoplasm) • Adenoma & Adenocarcinoma (the same as those seen in other parts of large bowel) • Malignant lymphoma

16. Appendix: Low grade appendiceal mucinous neoplasm ( LAMN) Mucocele Gross Pathology: -Cystic lesion with mucinous content. -No features of active inflammation associated, tend to be thin-walled Microscopic features: -Thin layer of mucinous epithelial lining as simple columnar or cuboidal cells without or only mild degree of nuclear atypia -In old cases, epithelial cells are denuded and sometime not identifiable

17. Appendicealmucocele with highly condensed mucus content Lesion is big and all epithelial lining disappeared Mucicarmine stain showing deep pink colored mucin

18. Malignant tumors: Mucinous cystadenocarcinoma, grossly also the mucoceles, but…. Mucinous cystadenocarcinomas: Grossly, the lesions maybe so large and show irregularity of lining due to active growth of of tumor cells forming protruding solid parts. Invasion of the tumor can lead to transmural involvement and rupture with serosal/peritoneal seeding. Confirmation of diagnosis needs thorough histopathologic study.

19. Mucinous cystadenocarcinoma of appendix, histopathology Microscopic features: -High-grade epithelial growth along the lining of the mucous cyst with active mucus secretion of the tumor cells which also show nuclear atypia. -Invasion of the tumor cells into the wall as that usually found in colonic carcinomas.

20. A case of appendiceal carcinoid with acute appendicitis Appendicitis with fibrinousexudate coated serosa A case of carcinoid tumor at terminal ileum Note the distinctive macroscopic features . Gross Pathology: -Tumor is solid with yellowish tan cut surface. -The edges of the lesion are usually non-circumscribed with infiltrative features even in well differentiated tumors. -Common location of involvement is at the tip of the appendix but can be found anywhere. -Low-grade lesions (well differentiated) tend to be small.

21. Carcinoid tumor (well differentiated neuroendocrine tumor) Insular (island) Glandular trabecular Microscopic features: -Common histopathologic patterns are insular and trabecular and glandular arrangement of tumor cel ls with rather uniform size. -Low-grade nuclear characters, uniform size and mild hyperchromatism. -Infiltration in surrounding structure is not the significant feature for diagnosis of high-grade lesion

22. Malignant Lymphomas of appendix and all parts of large bowels are rare comparing with those found in gastric and small bowel regions Gross and histopathologic features are the same. Malignant lymphoma of appendix, (rarely found) Neoplastic cells are lymphocytes with monotonus growth pattern Appendix Lymphoma at ileocaecal valve Lymphoma of ileum with perforation In all cases, note the homogeneously white cut surfaces of the lesions due to infiltration of the tumor which replaces the whole mural structures.