Chromoblastomycosis is believed to originate in minor trauma to the skin, usually from vegetative material such as thorns or splinters; this trauma implants fungi in the subcutaneous tissue. In many cases the patient will not notice or remember the initial trauma, as symptoms often do not appear for years. The fungi most commonly observed to cause chromoblastomycosis are Fonsecaea pedrosoi, Phialophora verrucosa, Cladosporium carrionii, and Fonsecaea compacta.

Over months to years, an erythematous papule appears at the site of inoculation. Although the mycosis slowly spreads, it usually remains localized to the skin and subcutaneous tissue. Hematogenous and/or lymphatic spread may occur. Multiple nodules may appear on the same limb, sometimes coalescing into a large plaque. Secondary bacterial infection may occur, sometimes inducing lymphatic obstruction. The central portion of the lesion may heal, producing a scar, or it may ulcerate.