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.

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.