Infectious Disease Online
Pathology of Granuloma Inguinale (Donovanosis)
Granuloma inguinale is a sexually transmitted, chronic, superficial ulceration of the genitalia and inguinal and perianal regions caused by Klebsiella granulomatis (formerly known as Calymmatobacterium granulomatis), a small, encapsulated, nonsporulating, nonmotile, gram-negative bacillus.
Granuloma inguinale is called Donovanosis because Donovan bodies are present in the scrapings from the edge of the lesions.
The organism has been cultivated in the yolk sac of embryonated chicken eggs and on media containing egg yolk.
The disease has been produced in volunteers but not in laboratory animals, and there is no similar disease in animals.
Granuloma inguinale is rare in temperate climates, but common in the tropics and subtropics.
New Guinea, central Australia, and India have the highest incidence.
Individual susceptibility varies greatly, and the low level of infectivity has sparked controversy about sexual transmission.
For instance, spouses of infected persons often remain uninfected despite repeated sexual contact. However, epidemiologic data favors sexual transmission.
Most patients are 15 to 40 years of age, the period of greatest sexual activity.
Because male homosexuals who take the passive role have only anal lesions, and because C. granulomatis has been isolated from faeces, the organism is thought to inhibit the intestinal tract.
It causes granuloma inguinale through autoinoculation, anal intercourse, or vaginal intercourse, when the vagina is colonized by enteric bacteria.
The incubation period varies from 1 to 5 months, 2 to 4 weeks being the average.
The initial lesion may be a papule, a subcutaneous nodule or an ulcer.
The lesion develops within several weeks into a raised, soft, painless, beefy-red, superficial ulcer.
The exuberant granulation tissue resembles a fleshy mass herniating through the skin.
In heterosexual men, early ulceration of the penoscrotal skin commonly extends to genitocrural and inguinal folds.
In women ulceration spread to the perineal and perianal skin. In homosexual men the lesions are perineal and anal.
Regional lymphadenopathy is not a feature.
Occasionally, however, subcutaneous inflammation in the inguinal regions may be confused with the bubo of lymphogranuloma venereum.
Sometimes granuloma inguinale can infect the vagina and cervix and mimic carcinoma.
Rarely, the infection disseminates to the pelvic organs, bone, and spleen following abortion or delivery.
Extragenital lesions of the skin and mucous membranes of the oral cavity have been reported.
Untreated granuloma inguinale follows an indolent, relapsing course, often healing, with an atrophic scar.
Secondary fusospirochetal infection may cause ulceration, with mutilation or amputation of the genitalia.
Massive cicatrization of the dermis and subcutis causes genital elephantiasis, probably by lymphatic obstruction.
It is uncertain whether there is an association between granuloma inguinale and squamous cell carcinoma, because the diseases share common risk factors, such as poor hygiene, fusospirochetal flora, and a large number of sexual partners.
Microscopically, there is epithelial hyperplasia of the ulcer margin.
The dermis and subcutis are infiltrated by numerous histiocytes and plasma cells and by fewer neutrophils and lymphocytes.
The neutrophils in the ulcer bed are clustered into poorly defined microabscesses.
Interspersed histiocytes contain many bacteria , which are called Donovan bodies.
The bacteria are difficult to see in routinely stained sections but are clearly revealed by silver impregnation.
In older lesions, the inflammatory cell infiltrate is composed of lymphocytes and plasma cells, and the organisms are difficult to find.
Diagnosis of granuloma inguinale is suggested by the clinical appearance of the lesion and confirmed by the demonstration of C. granulomatis in smears of ulcer scrapings or tissue sections.
A combined regimen of trimethoprim and sulfamethoxazole is the treatment of choice.
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