Toxoplasma gondii mimicking metastatic neoplasia in a senior indoor-only cat

Abstract

An 11-year-old cat presented for a 1-week history of dyspnoea. The cat had a history of allergies that were being managed on cyclosporine. Physical examination revealed an increased respiratory rate and effort, and the cat was oxygen dependent. Thoracic radiographs revealed a severe diffuse nodular pulmonary pattern, suggestive of metastatic neoplasia. An abdominal ultrasound was performed to evaluate for a primary mass or evidence of disseminated disease. A 4.3 × 2.2 cm ileocolic mass was noted. Fine-needle aspirates of the intestinal mass were poorly exfoliative. Toxoplasma gondii titres were performed (IgM <1:20 and IgG >1:20,480). Fine-needle aspirates of the pulmonary nodules revealed neutrophilic and macrophagic inflammation with large numbers of 2–4 µm, crescent-shaped organisms, consistent with Toxoplasma gondii. Cyclosporine was discontinued and clindamycin was prescribed. The cat was discharged 3 days later. Repeat imaging revealed resolution of the pulmonary and intestinal lesions. Clinical cure was achieved.