Tuberculosis of the appendix
HIV positive. Weight loss and fevers.
CT Abdomen and pelvis
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The appendix lies within the right paracolic gutter with tip adjacent to the inferior border of the right lobe of the liver. The appendix is dilated and measures up to 12 mm. It demonstrates very prominent wall enhancement, and there is surrounding fat stranding. No appendicolith. No peri-appendiceal collection. The remainder of the large bowel is unremarkable.
The terminal ileum appears diffusely abnormal. It is dilated and demonstrates prominent wall enhancement. There is no evidence of bowel obstruction.
Multiple ring-enhancing lesions are demonstrated in the central mesentery extending into the right iliac fossa which demonstrates central low attenuation. Together this measure up to 9.2 x 2.5 cm in maximum axial dimension. The appearances suggest multiple necrotic lymph nodes. There is associated mesenteric fat stranding and small pockets of fluid within the abdomen and pelvis, most prominent in the pouch of Douglas. Mildly enlarged inguinal lymph nodes bilaterally.
The spleen is enlarged, measuring approximate 12.7cm in bipolar length, without focal abnormality.
The liver, pancreas, adrenal glands and kidneys have a normal appearance.
Within the posterior segment of the left lower lobe, there is a wedge-shaped area of a tree in bud opacity. This is associated with a 13 mm ovoid opacity. No pleural effusion.
No suspicious bony lesion.
A combination of findings, including multiple necrotic mesenteric lymph nodes, abnormal terminal ileum, and left lower lobe pulmonary changes suggest a diagnosis of tuberculosis.
The appendix is abnormal and suspicious for appendicitis however the underlying aetiology may also be tuberculous.
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-necrotising 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-necrotising, 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