Bacteria

Morphology

Cytology:

• Intracellular gram-negative bacterium
• Diagnosis requires visualization of Donovan bodies: dark-staining, encapsulated, pleomorphic rods (1-2 µm) with characteristic bipolar ("safety-pin") appearance due to prominent polar granules
• Organisms located within single or multiple intracytoplasmic vacuoles of large mononuclear cells (histiocytes/macrophages); extracellular organisms may also be present
• Best visualized with Giemsa, Wright, or Leishman stain; also detectable on Papanicolaou-stained smears
• Tissue crush preparation from the lesion base is the preferred specimen
• Very few epithelial cells
• Intakt capillaries may be seen due to ulceration of overlying epithelium

Histology:

• Dense dermal/subepithelial inflammatory infiltrate composed of plasma cells, histiocytes/macrophages, and neutrophils
• Large mononuclear cells with single or multiple intracytoplasmic vacuoles containing Donovan bodies
• Overlying pseudoepitheliomatous hyperplasia is characteristic but not specific, and may histologically mimic squamous cell carcinoma (SCC)
• In advanced cases, tissue destruction and extension beyond the dermis may occur. Transepithelial elimination of the organisms has been reported. (1)

Clinical notes

Sexually transmitted; low infectivity (repeated contact usually required). Painless, slowly progressive, "beefy red" genital ulcers that bleed easily; no lymphadenopathy - distinguishing feature from other genital ulcer diseases. Subcutaneous granulomas (pseudobuboes) may occur. Extragenital spread possible (pelvis, bone, oral). Co-infection with syphilis and HIV common. Without treatment, progressive tissue destruction over months to years; donovanosis may mimic SCC clinically.
Rare in the United States; sporadic cases reported from India, South Africa, and South America. Australia now extremely rare. (2)

Ancillary Testing

Additional Information

HIV screening is recommended in all patients with genital ulcers.