Disseminated toxoplasmosis. Unusual presentations in the immunocompromised host

Owing to the increasing number of patients with acquired immunodeficiency syndrome and immunosuppressed transplant patients, disseminated Toxoplasma gondii has emerged as a potentially fatal pathogen. Common presentations include encephalitis, pneumonia, and myocarditis. The objective of this report is to describe the clinical course, histologic features, and outcome in two immunocompromised patients with disseminated toxoplasmosis presenting with parasitemia and panniculitis.

Two cases of disseminated toxoplasmosis presenting with parasitemia (patient 1) and panniculitis (patient 2) were retrieved from the clinical, surgical, and autopsy pathology archives of Vanderbilt University Medical Center, Nashville, Tenn. The histology and diagnostic approaches used are reported. Charts were reviewed for primary diagnosis, therapy protocols, clinical presentation of infection, and outcome.

Patient 1 developed a clinically unexplained sepsis syndrome shortly after heart transplantation; T gondii parasitemia was diagnosed by examination of peripheral blood smears. The diagnosis was confirmed at autopsy. Patient 2 was a child undergoing induction chemotherapy for lymphoma who developed rapidly progressive neurologic deterioration accompanied by a maculopapular skin rash; T gondii panniculitis was diagnosed retrospectively when histologic examination was combined with immunohistochemistry. Autopsies performed in both cases confirmed widely disseminated infection.

Disseminated toxoplasmosis should be considered in the differential diagnosis of immunocompromised patients with culture-negative sepsis syndrome, particularly if combined with neurologic, respiratory, or unexplained skin lesions. Examination of Wright's-stained peripheral blood smears or antitoxoplasma immunoperoxidase studies of skin biopsies may be diagnostic and allow rapid initiation of antibiotic therapy. Autopsy findings contributed to both of our cases by documenting the wide-spread heavy parasite burden and demonstrating numerous diagnostic T gondii cyst forms.