Anthrax

For medical students2 min readUpdated 2026-10-10

Pathomorphological changes in the body during anthrax develop in stages, affecting the intestine and the lymphatic system. The process includes necrosis, ulceration, and subsequent healing with characteristic morphological features.

Timing of ulcerationBegins in the 3rd week of the disease

"Dirty" ulcersThe base is covered with necrotic detritus

Perforation riskIn the 4th week due to thinning of the intestinal wall

HealingRestitution-type repair by the 5th week

Ulceration Stage

In the third week of the disease, the rejection of necrotic masses in the intestine begins. During this period, "dirty" ulcers form, exactly mimicking the shape of the follicles and Peyer's patches.

Surface: uneven and dull.
Edges: overhanging the base.
Base: covered with necrotic detritus.

The pathological process affects tissues sequentially: changes are first registered in the distal ileum and then spread to the proximal segment.

Clean Ulcers Stage and Potential Complications

In the fourth week of the illness, the rejection of necrotic masses is completed, and mucosal defects transition into the stage of clean ulcers.

The shape of the ulcers becomes oval or round.
The edges acquire an even, slightly rounded appearance.
The base becomes smooth.

Complication: In some cases, only a very thin intestinal serosa remains as the base of the ulcer. This creates a critical risk of intestinal perforation, which inevitably leads to severe peritonitis.

Healing and Repair

In the fifth week, the healing process of intestinal defects starts. Delicate scars form at the site of the former ulcers, and lymphoid tissue gradually regenerates.

The reparative process proceeds via restitution, meaning complete structural restoration.
Clinical feature: at this stage, a striking mismatch is often observed — the patient's well-being is already good, while morphological changes in the intestine still persist.

Mesenteric Lymph Node Reaction

Mesenteric lymph nodes undergo changes that mirror the processes in the intestine:

Initial stage: nodes enlarge and become hyperemic; monocytes and reticular cells actively proliferate and displace lymphoid elements.
Granulomatous stage: specific granulomas form.
Outcomes: granuloma necrosis followed by organization and petrification (calcification) of the necrotic masses.

Frequently asked questions

What pathomorphological changes occur in Peyer's patches during the first and second weeks of the disease?

During the first and second weeks of the disease, pathomorphological changes in Peyer's patches undergo two consecutive stages.

Stage of medullary swelling — against the background of catarrhal enteritis, solitary follicles enlarge, swell, acquire a grey-red color, and protrude into the intestinal lumen; their surface becomes uneven.
Stage of necrosis — in the second week, necrosis of the lymphoid tissue of the follicles occurs.

What is the exact cellular composition of specific granulomas forming in the mesenteric lymph nodes?

The provided sources do not fully disclose the exact complete cellular composition of typhoid granulomas in the mesenteric lymph nodes. The following is indicated:

Changes similar to intestinal ones occur in the mesenteric lymph nodes.
At the initial stage, nodes are enlarged and hyperemic; proliferation of monocytes and reticular cells is observed, which displace lymphoid elements.
Typhoid granulomas then form.
Specific macrophages — typhoid cells — form granulomas.
Subsequently, necrosis of granulomas, their organization, and petrification of necrotic masses are possible.

What systemic (extraintestinal) complications can develop in this disease?

In this disease, a number of severe extraintestinal complications affecting various organ systems can develop.

Secondary infection — includes the development of meningitis, meningoencephalitis, bronchopneumonia, and intramuscular abscesses.
Non-ulcerative peritonitis — occurs due to necrosis of mesenteric lymph nodes or rupture of the splenic capsule.
Typhoid sepsis — proceeds with a pronounced typhoid status in the absence of significant intestinal changes.
Rare complications — include purulent perichondritis, osteomyelitis, arthritis, cystitis, prostatitis, and waxy necrosis of the rectus abdominis muscles.

What changes occur in the intestine in the 3rd week?

In the 3rd week, the ulceration stage begins: necrotic masses are sloughed off, forming "dirty" ulcers with an uneven surface and overhanging edges.

What is the danger of the 4th week of the disease for the intestine?

In the 4th week, only a thin serosal layer may remain at the base of the ulcer, creating a high risk of intestinal perforation and the development of peritonitis.

How does ulcer healing proceed in the 5th week?

In the 5th week, delicate scars form, lymphoid tissue recovers, and repair proceeds via restitution (complete restoration).

Go deeper

Pathogenesis of necrotic mass sloughing in Peyer's patches
Microscopic picture of solitary follicles stained with hematoxylin and eosin
Structure and role of specific macrophages (granuloma cells)
Developmental stages and outcomes of mesenteric lymph nodes
Signs of petrification of necrotic masses in lymph nodes