General information
This venereally transmitted infection is caused by gram negative, encapsulated coccobacillary organisms called Calymmatobacterium granulomatis. The infection produces large ulcerated lesions that histologically reveal inflammatory granulation tissue and numerous macrophages. Bacteria are found in the cytoplasm of neutrophils, histiocytes and plasma cells (Donovan bodies), and assumes the shape of a safety pin. The infection is more common in the tropics.

Cytology
Macrophages swollen with large numbers of coccobacillary structures (Donovan bodies)
Safety pin shaped

Special note
Gram negative