A 24-year-old woman with Crohn’s disease who had been receiving maintenance therapy with adalimumab (40 mg every 2 weeks) for 4 years presented with fever, moderate respiratory distress, and weight loss. She had travelled to Costa Rica three months prior to presentation.

The patient had leucopenia (3.3 G/l) and moderately elevated liver enzymes. Thoraco-abdominal computed tomography revealed diffuse pulmonary micronodules with a miliary distribution, ground-glass opacities (figure 1), and hepatosplenomegaly (not shown). HIV testing was negative.

Figure
Figure 1: Thoracic computed tomography images illustrating multiple diffuse pulmonary micronodules with miliary/ haematogenous distribution and ground-glass opacities.

Antituberculous therapy was initiated, but the nucleic acid amplification test (NAAT) for Mycobacterium tuberculosis performed on bronchoalveolar lavage (BAL) fluid was negative. However, the NAAT, consisting of an in-house panfungal PCR targeting 26S rRNA, identified Histoplasma capsulatum. Histopathological examination of transbronchial biopsies revealed Histoplasma yeasts (figure 2).

Figure
Figure 2: Histopathological examination of transbronchial biopsies on hematoxylin and eosin staining and Grocott methenamine silver staining, respectively (objective magnification ×40) indicating the Histoplasma yeasts (arrow and ellipse, respectively).

The patient was treated with liposomal amphotericin B (3 mg/kg/day for 12 days), followed by itraconazole (200 mg twice daily for 12 months) [1], resulting in improvement. Histoplasmosis may be fatal in patients receiving tumour necrosis factor-alpha inhibitors and may mimic miliary tuberculosis [2].