Infectious Disease Online
Pathology of Whipple's Disease
"Macrophages containing diastase resistant PAS positive granules in the lamina propria of the small intestinal biopsy is key to the diagnosis"
Whipple's disease is a rare chronic, relapsing, and multisystem disease
caused by bacterial infection.
It was first described by George H. Whipple in 1907 and in 1949, the typical histological picture of the intestinal mucosa was described displaying foamy macrophages with cytoplasmatic periodic acid-Schiff (PAS) reactivity.
The etiology was further clarified in 1961 by detecting bacteria by electron microscopy.
Causative organism: Gram-positive organism named Tropheryma whipplei. The name of this bacterium—Tropheryma whipplei—is derived from Greek "trophe" (nourishment and food) and "eryma" (fence and barrier).
Age: Patients in fourth
and fifth decade of life.
Sites affected: Intestine, central nervous system, joints, lymphnodes, lungs and heart.
The affected bowel is usually edematous with yellow plaque-like lesions and villiferous mucosa.
Affected lymph nodes appear yellow with a spongy cut surface.
Other affected organs, such as lungs and heart, may show plaques and edema.
Small intestinal mucosa filled with distended macrophages in the lamina propria.
The macrophages contain diastase resistant PAS positive granules.
Villi may be distorted.
Inflammation is usually absent.
Mesenteric lymphnodes may be involved and may show lymphatic dilatation indicating lymphatic obstruction.
Microscopic findings in the CNS include PAS-positive intracellular and extracellular organisms surrounded by reactive astrocytes.
The organisms may also violate the subarachnoid spaces and lead to the death of neurons, vacuolization, and demyelination.
Diagnosis: The diagnosis is usually established by small intestinal biopsy, which shows the pathognomonic periodic acid Schiff-positive infiltrates in the lamina propria.
The rod shaped bacilli may be demonstrated by electron microscopy.
Polymerase chain reaction is now available to aid in the diagnosis of WD, and this organism has been identified by polymerase chain reaction in many body fluids, including cerebrospinal fluid, aqueous humor, and synovial fluid.
cerebrospinal fluid and peripheral blood is less consistent than in
diagnosis: Includes AIDS
enteropathy caused by Mycobacterium avium intracellulare
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