Granuloma inguinale. Light micrograph of a section through tissue from a perianal ulcer from a 19-year-old female patient with granuloma inguinale (donovanosis), showing epithelial hyperplasia and accompanying cellular infiltrate of histiocytes and plasma cells. Granuloma inguinale is a rare sexually transmitted disease (STD) caused by infection with Klebsiella granulomatis bacteria. It causes open genital lesions (ulcers) that can destroy underlying tissue. Treatment is with antibiotics.