Paracoccidioidomycosis has recently been classified into juvenile (acute) and adult (chronic) forms. The latter affects middle-aged men and causes mucocutaneous lesions, while the more rare juvenile form affects the reticuloendothelial system of children and adults of both sexes under 30 years of age. It is not yet known, however, if the patient's age has a role in determining the immune response patterns to the fungus and the evolution to one form or the other. We present a 45-year-old man who presented with juvenile type disease characterized by intra-abdominal polyadenopathy forming a large epigastric mass. Immune evaluation showed high titres of anti-Paracoccidioides brasiliensis antibodies and an antigen-specific cellular immune defect. Treatment resulted in resolution of the clinical and immune abnormalities. His epidemiological background also suggested acute disease: he developed disease after moving from an urban to a rural endemic area. We suggest that acute or juvenile disease may occur in a previously healthy, susceptible individual when moving to an endemic area, at whatever age.