Isolated Mediastinal Lymphadenitis Caused by Toxoplasma Infection in an Immunocompetent Adult

A 71-year-old female with no respiratory symptoms was admitted to our hospital for preoperative assessment before cataract surgery. All physical examination and laboratory findings were normal, but a chest x-ray showed bilateral hilar enlargement. Computed tomography (CT) of the chest revealed multiple lymphadenopathy involving the paratracheal, precarinal, subcarinal, aorticopulmonary and hilar nodes. Tuberculous lymphadenitis was suspected because there was a family history of tuberculosis and the patient’s tuberculin skin test was positive. Excisional biopsy of the right scalene lymph node was performed, and pathologic examination revealed the characteristic features of toxoplasmic lymphadenitis. Testing showed that the patient was negative for immunoglobulin IgM antibodies to Toxoplasma, but had high Toxoplasma IgG avidity, which supported chronic Toxoplasma infection. Follow-up CT studies at 6 months, 1 year, 2 years revealed no changes in the lymphadenopathy. No further diagnostic testing was done and no therapy was administered. This case is noteworthy because it documents the rare finding of mediastinal lymphadenopathy in Toxoplasma infection and shows that it is appropriate to follow this condition without treatment in immunocompetent patients who are asymptomatic.