Tuberculosis of the appendix
MICROSCOPIC DESCRIPTION: Sections show an appendix with extensive ulceration of the mucosa. The lumen of the appendix contains a suppurative exudate with the ulcerated area showing active inflammation and is in areas is lined by epithelioid histiocytes. In the wall deep to the ulceration there is granulomatous inflammation, comprising multiple variably sized granulomat, which are predominantly non-necrotizing but a few shows some central necrosis, with these necrotic ones occuring close to the ulcerated surface. Surrounded the granulomata is a mixed inflammatory infiltrate which is predominantly chronic comprising lymphocytes, plasma cells, occasional eosinophils and numerous epithelioid histiocytes, but there are scattered neutrophils. In areas deeper to this, the mixed transmural inflammatory infiltrate continues to become transmural, remaining predominantly chronic but with scattered neutrophils. There is no evidence of dysplasia or malignancy. No bacteria are identified with a Gram stain; no mycobacteria are identified with Ziehl-Neelsen or Wade-Fite stains; and no fungal organisms are identified with a periodic acid-Schiff stain or Grocott stain (laboratory fungal contaminants are observed on the Grocott).
DIAGNOSIS: Appendix: Acute on chronic granulomatous appendicitis; with multiple granulomata, most non-necrotizing, but with a few showing necrosis. COMMENT: The differential diagnoses include tuberculosis, atypical mycobacterial infection, Yersinia infection and Crohn's disease. In the clinical context, infection, particularly with tuberculosis, is considered far more likely than Crohn's disease. Formalin fixed paraffin embedded tissue from the appendix has been referred for Mycobacterium tuberculosis and atypical mycobacterial PCR.
The low-density abdominal lymph nodes and the abnormal terminal ileum are also highly suspicious of involvement with TB