Histology

In histologic sections, amastigotes usually stain well with H&E or Brown-Hopps modified tissue gram stain, and are readily observable if abundant. Parasites may be very sparse in late lesions, requiring review of multiple tissue sections. Oil-immersion observation with a 100x objective is mandatory for these cases. In our experience, Brown-Hopps modified tissue gram stain best accentuates the kinetoplast, and produces minimal background staining and maximum contrast. Giemsa stains are of no value in tissue sections.

In vitro culture is more sensitive than histological methods, but because some Leishmania sp. are difficult to culture, this method should be complementary to microscopy, especially in clinically suspect cases.

There is currently no sensitive or specific serological assay for detecting Leishmania-specific antibody in CL. A skin-test antigen can detect prior infection and corroborate the diagnosis of oligoparasitic syndromes; however, no such test is currently available in the United States for clinical use.