A UNIQUE CASE OF DISSEMINATED HISTOPLASMOSIS MISDIAGNOSED AS INVASIVE ASPERGILLOSIS

SESSION TITLE: Fellows Chest Infections Posters SESSION TYPE: Fellow Case Report Posters PRESENTED ON: October 18-21, 2020 INTRODUCTION: When Histoplasma microconidia is inhaled into the lung and changed into the yeast form, a respiratory infection can occur. Disseminated disease may have gastrointestinal, skin, central nervous system, and cardiac involvement. We present a unique case of fulminant respiratory failure from histoplasmosis initially misdiagnosed as aspergillosis. CASE PRESENTATION: A 65-year-old male with past medical history of HIV (CD4 210, VL 552,780 from two weeks ago) and alcoholic liver disease presented with generalized fatigue and decreased appetite of one-week duration. Patient admitted to dry cough, but denied fever, chest pain or dyspnea. Vital signs showed: T 98.5, BP 99/58, HR 91, RR 18, saturating 88% on room air. Physical exam was significant for rales bilaterally. Metabolic panel was remarkable for: Na 128, AST 112, ALT 58, ALP 223, Albumin 1.5. Other labs include: LDH 252, lactic acid 3.1, procalcitonin 0.57. Blood counts revealed: WBC 2200 with ANC 1500, platelet count 47, and INR 1.42. CT chest angiogram showed extensive bilateral airspace opacities, enlarged mediastinal and hilar lymph nodes, and splenomegaly. ABG showed pH 7.44, pCO2 23.6 and pO2 49 on room air. Patient was started on trimethoprim-sulfamethoxazole, levofloxacin, and steroids to include coverage for Pneumocystis jirovecii and community-acquired pneumonia. Patient’s respiratory status worsened, and he was intubated. Meanwhile, an Aspergillus galactomannan antigen (1.65) and serum fungitell (162) were elevated. While entertaining a diagnosis of aspergillosis, a bronchoalveolar lavage was done which demonstrated scattered macrophages containing yeast-like structures suggestive of Histoplasmosis. Urine histoplasma antigen and Histoplasma buffy coat testing with acridine came back positive. Patient began treatment with amphotericin B for disseminated histoplasmosis, improved significantly, and was extubated. DISCUSSION: Diagnosis of Histoplasmosis is established by direct microscopy, cultures, or antigen detection. However, as initial lab results were pending, our patient was misdiagnosed as invasive aspergillosis. This is important to avoid since voriconazole has limited efficacy in histoplasmosis. Galactomannan (GM) is a polysaccharide cell wall component of Aspergillus species and the target of detection by the galactomannan enzyme-linked immunoassay. However, it confers cross-reactivity with other fungal species in which GM is a component of their cell walls, including Histoplasma, Blastomyces, Paracoccidioides, Cryptococcus, Paecilomyces, Trichothecium, Lichtheimia ramose, and Geotrichum species. CONCLUSIONS: It is important to be cognizant of cross-reactivity of aspergillus galactomannan antigen and subsequent false positive tests in patients with histoplasmosis. Reference #1: Min, Z., et. al. (2012). Cross-reactivity of Aspergillus galactomannan in an HIV-infected patient with histoplasmosis. Medical Mycology Case Reports, 1(1), 119–122. Reference #2: Giacchino M., Chiapello N., Bezzio S., Fagioli F., Saracco P., Alfarano A. Aspergillus galactomannan enzyme-linked immunosorbent assay cross-reactivity caused by invasive Geotrichum capitatum. Journal of Clinical Microbiology. 2006;44(9):3432–3434. Reference #3: 3. Cummings J.R., Jamison G.R., Boudreaux J.W., Howles M.J., Walsh T.J., Hayden R.T. Cross-reactivity of non-Aspergillus fungal species in the Aspergillus galactomannan enzyme immunoassay. Diagnostic Microbiology and Infectious Disease. 2007;59:113–115. 4. Xavier M.O., Pasqualotto A.C., Cardoso I.C., Severo L.C. Cross-Reactivity of Paracoccidioides brasiliensis, Histoplasma capsulatum, and Cryptococcus species in the commercial platelia Aspergillus enzyme immunoassay. Clinical and Vaccine Immunology. 2009;16(1):132. 5. Borrás R., Roselló P., Chilet M., Bravo D., de Lomas J.G., Navarro D. Positive result of the Aspergillus galactomannan antigen assay using bronchoalveolar lavage fluid from a patient with an invasive infection due to Lichtheimia ramosa. Journal of Clinical Microbiology. 2010 Aug;48(8):3035–3036. DISCLOSURES: No relevant relationships by Sudipa Chowdhury, source=Web Response No relevant relationships by William Meng, source=Web Response No relevant relationships by Richard Miller, source=Web Response No relevant relationships by Sushant Nanavati, source=Web Response No relevant relationships by Rutwik Patel, source=Web Response No relevant relationships by Hari Sharma, source=Web Response