Should histoplasmosis be screened for before initiation of tumour necrosis factor alpha inhibitors?

Histoplasmosis is a soil based dimorphic fungus endemic to the Midwest and Southeastern United States and is responsible for infection through inhalation of conidia. Infection is usually asymptomatic, as the fungal growth is contained by formation of granulomas. However, dissemination can occur in immunocompromised hosts due to the lack of optimal activity of interferon gamma, tumor necrosis factor-alpha (TNF-alpha) and interleukin-17. There is a significant overlap between the symptomatology of histoplasmosis and granulomatosis with polyangiitis (GPA). We are reporting a case of a 48-year-old female who presented with high grade fever, worsening generalized weakness and tachycardia. She had a previous history of bilateral cavitary lung lesions for which she was evaluated at an outside facility. As her entire infectious work up was negative and found to be positive for antineutrophil cytoplasmic antibody (ANCA), a diagnosis of GPA was made and she was initiated on rituximab infusions 7 weeks prior to her presentation to our facility. Repeat infectious work up at our facility was positive for (1,3) beta-D-glucan test and urine histoplasma antigen. Prompt discontinuation of rituximab and initiation of systemic antifungal therapy led to clinical improvement. Based on this experience we would like to highlight the association of histoplasma with ANCA positivity along with the importance of closely monitoring these patients, for possible clinical worsening after the initiation of immunosuppressive therapy, despite the negative infectious work up.