Disseminated histoplasmosis in patients receiving low-dose methotrexate therapy for psoriasis

Low-dose methotrexate sodium therapy used for nonmalignant disease has been associated with a variety of opportunistic infections with pathogens occurring in patients with defective cellular immunity. This article describes the unusual development of disseminated histoplasmosis as a probable complication of immunosuppression resulting from use of methotrexate.

We report the cases of three patients in whom disseminated histoplasmosis developed while receiving low-dose methotrexate therapy for psoriasis. Disease manifestations were unusually severe in two of the three patients. All three cases were disseminated, and two cases resulted in illnesses requiring intensive medical treatment. Each patient responded appropriately to antifungal treatment, although one patient has required long-term suppressive treatment because of persistent Histoplasma antigenuria. These cases illustrate the risk for opportunistic fungal infections in patients receiving low-dose methotrexate therapy for nonmalignant diseases.

Histoplasma should be added to the list of pathogens to be suspected in patients receiving such therapy.