Granulomatous diseases Flashcards
Examples of what could cause a granulomatous disease?
Parasites, mycobacteria, fungi, viruses, foreign material.
What are the characteristics of granulomatous disease and what are they caused by?
Granulomatous inflammation is present in which macrophages predominate. Caused by irritants or agents that are persistent and not easily degraded by macrophages.
What is the difference between a granuloma and a granulomatous disease?
A granuloma is a focally discrete, closely packed aggregate of macrophages surrounded by a zone of lymphocytes and plasma cells with an outer rim of fibroblasts. They can have a central necrotic area. Granulomatous disease is inflammation that causes thickening rather than being focal.
What cells can be present?
GD-macrophages, giant cells and lymphocytes.
Eosinophilic GD- mac + eosinophils
Pyogranulomatous disease- mac + neutrophils
What are the viruses that cause granulomatous infection?
Feline coronavirus- (FIP) and Porcine Circovirus.
How does FIP develop?
Feline enteric coronavirus is present asymptomatically in cats, it mutates (closely related) into FIP by the gene 3c. This allows it to enter macrophages and cause disease.
What happens in FIV?
There is an immune mediated vasculitis when infected macrophages accumulate around the blood vessels. If it is wet FIP it causes pleural and peritoneal disease, if it is dry FIP it causes neurological and occular disease.
What is postweaning multisystemic wasting syndrome and its clinical signs? (PMWS)
It is a PCV-2 associated disease (PCVAD). Not all pigs will show clinical signs when infected. weight loss, jaundice, aponea. Enlargement of the lymphnodes and inflammation in the lungs, liver and kidneys. There are granulomatous lesions here too.
What is PDNS?
Porcine dermatitis and nephropathy syndrome is another (PCVAD). It causes skin and kidney lesions and is immune mediated.
How does foreign material induce granulomatous responses?
It is impossible for the macrophages to phagocytose it. e.g. sutre material/swabs. A hair follicle can escape its shaft and go into the dermis where a pyogranulomatous reaction will occur called furunculosis
Examples of ideopathic causes of granulomatous reactions?
Granulomatous meningoencephalitis- nervous system of Middle aged small dogs. There are few lesions but there ,ay be some discolouration histologically e.g. necrosis of white matter.
Feline eosinophilic granuloma complex, eosinophilic plaque, idolent ulcer.
What spp of Mycobacteria can cause granulomatous disease?
M.bovis- TB in cattle M.TB- TB in humans M.leprae- leprosy M.lepraemurium- feline leprosy M.a. Paratuberculosis- Johne's disease.
How do mycobacteria cause granulomatous disease?
They have a very special cell wall that allows them to survive inside phagosomes within the macrophage. A granuloma forms to wall off the infection and prevents the spread of bacteria.
What is critical about Johne’s disease in sheep?
There are two types: multibacillary- mac + giant cells, lots of acid fast bacteria so +ve on ZN stain of faeces, Paucibacillary- few mac, lots of lymphocytes, so can get false -ve on ZN stain of faeces due to low bact.
What does M. lepraemurium do?
cause feline leprosy which manifests as chronic cutaneous nodules that are resistant to normal antibiotics.
