Without treatment, borderline leprosy may become less severe and more like the tuberculoid form, or it may worsen and become more like the lepromatous form.

Without treatment, borderline leprosy may become less severe and more like the tuberculoid form, or it may worsen and become more like the lepromatous form.

Susceptibility to progressive infection in the lepromatous form correlated with the local expression of genes encoding members of the leukocyte immunoglobulin-like receptor (LIR) family, including LIR-3, -4, -7, and - 8.

Both types produce lesions on the skin, but the lepromatous form is more severe and causes the additional formation of large lumps and bumps.