Granuloma inguinale, or donovanosis, is a chronic inflammatory disease caused by Calymmatobacterium donovani, a minute, encapsulated, coccobacillus that is closely related to the Klebsiella genus. The organism is sexually transmitted.
Granuloma inguinale is uncommon in the United States and western Europe but is endemic in rural areas in certain tropical and subtropical regions.
Untreated cases are characterized by the development of extensive scarring, often associated with lymphatic obstruction and lymphedema (elephantiasis) of the external genitalia. Culture of the organism is difficult, and PCR assays are still in development, so the diagnosis is made by morphologic examination of smears or biopsies of the ulcer.
Morphology. Granuloma inguinale begins as a raised, papular lesion involving the moist, stratified squamous epithelium of the genitalia or, rarely, extragenital sites including the oral mucosa or pharynx. The lesion eventually undergoes ulceration, accompanied by the development of abundant granulation tissue, which is manifested grossly as a protuberant, soft, painless mass.
As the lesion enlarges, its borders become raised and indurated. Disfiguring scars may develop in untreated cases and are sometimes associated with urethral, vulvar, or anal strictures. Regional lymph nodes typically are spared or show only nonspecific reactive changes, in contrast to chancroid.
Microscopic examination of active lesions reveals marked epithelial hyperplasia at the borders of the ulcer, sometimes mimicking carcinoma (pseudoepitheliomatous hyperplasia). A mixture of neutrophils and mononuclear inflammatory cells is present at the base of the ulcer and beneath the surrounding epithelium.
The organisms are demonstrable in Giemsa-stained smears of the exudate as minute, encapsulated coccobacilli (Donovan bodies) in macrophages. Silver stains (e.g., the Warthin-Starry stain) may also be used to demonstrate the organism.