17.6 The Serosal Fire and the Silent Deposits

Time To Read

5–7 minutes

Date Last Modified

Age 45


Recurrent Peritonitis and Gut Amyloidosis

1

Recurrent Sterile Attacks

2

Whole-Abdomen, Fever-Plus, Infection-Negative Attacks

3

Chronic Heartburn

4

Malabsorptive Symptoms

5

Persistently Elevated SAA and Rising Cholesterol

6

Biopsy-Proven Gut Amyloid

7

Recurrent Peritonitis and Gut Amyloidosis

Stina’s gut is being attacked in two completely different ways, on two different timescales. The first is loud and acute: peritonitis. FMF is a disease of serositis – inflammation of the serous membranes – and the peritoneum lining the abdomen is its most common target. When IL-1b-driven inflammation flares, the peritoneum becomes acutely inflamed without any infection, producing exactly Stina’s picture: sudden severe abdominal pain, rigidity, tenderness, and fever, lasting a day or two and then resolving. Because sterile peritonitis mimics a surgical abdomen so faithfully, it is classically mistaken for appendicitis – which is why a nineteen-year-old with FMF can lose a perfectly normal appendix. This is the same serositis that, elsewhere in the case, inflames her pericardium and her pleura; the abdomen is simply where it strikes most often.

The second attack is silent and chronic: amyloid. The SAA her liver has been overproducing for decades deposits, fragment by fragment, as AA amyloid fibrils in the wall of the GI tract – often beginning in the small intestine and its immune-rich Peyer’s patches. Unlike the dramatic attacks, this process announces itself quietly, as malabsorption: loose stools, bloating, and the slow weight loss now appearing in her chart. The gut is, in fact, one of the first places AA amyloid tends to land, which makes Stina’s newer symptoms an early warning, not a footnote. Read together, the loud attacks and the quiet deposits are two faces of one disease: chronic IL-1b/IL-6 inflammation inflaming the serosa from outside and seeding amyloid within. Neither is irritable bowel, a stomach bug, or stress.

For Stina, the two threats finally show themselves as one. The serosal fire is sterile peritonitis — the peritoneum, a serous membrane much like the pericardium, inflaming across the whole belly to produce her fever-and-pain attacks. The silent deposits are amyloid — misfolded from the liver’s chronically elevated SAA — infiltrating her gut wall and producing her malabsorption. They look unrelated, one loud and episodic, one quiet and chronic, but both flow from the same chronic inflammation: one inflames the membrane, the other petrifies the wall. And because the peritoneum’s serous kin include the pleura and pericardium, this fire is not confined to her belly.

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