Fusarium and Lomentospora Coinfection in a Pediatric Patient with Acute Myelogenous Leukemia: Always Occam's Razor May Not Apply.

•Coinfection with two invasive molds, Fusarium and Lomentospora, is a rare phenomenon.•Invasive fungal infections are difficult to treat; high mortality is associated with host immune status.•Anchoring bias based on the initial diagnosis can delay the diagnosis of a coinfection. A 14-year-old female with acute myelogenous leukemia presented with 1 day of fever, myalgias, and a single necrotic lesion on her left foot. She was undergoing intensification chemotherapy, was severely neutropenic for 2 weeks, and was taking prophylactic voriconazole. Biopsy of the necrotic lesion revealed angioinvasive fungal elements, with Fusarium growing from culture (Figure 1). Whole-body imaging revealed lung nodules with halo sign (Figure 2).Figure 2Images from chest computed tomogaphy with contrast, showing multiple irregular, solid nodules with surrounding ground-glass opacity (halo sign, red arrow) throughout both lungs, without central cavitation. Dominant nodules noted in the right lung are shown. (a) Right lower lobe lesion measuring 1.1 × 1.1 cm. (b) Right lower lobe medial superior segment lesion measuring 0.9 × 0.8 cm. (c) Right upper lobe apical lesion measuring 1.6 × 1.2 cm.View Large Image Figure ViewerDownload Hi-res image Download (PPT) On day 2 of hospitalization, the results of in-house polymerase chain reaction testing of plasma cell-free DNA were positive for Scedosporium spp. Blood cultures that were drawn at admission grew mold with septate hyphae at 56 hours. The mold was presumed to be Fusarium; however, it was identified as Lomentospora prolificans (Figure 3). Treatment with liposomal amphotericin B and granulocyte colony-stimulating factor was initiated. Voriconazole was replaced with intravenous posaconazole on day 4. Terbinafine was added on day 7 but was discontinued after 24 hours due to transaminitis. Despite aggressive therapy, the patient remained persistently fungemic, developed multiorgan failure, and died on day 9 of hospitalization. Coinfection with invasive molds is rare; few cases have been described (Amirrajab et al., 2015Amirrajab N Aliyali M Mayahi S Najafi N Abdi R Nourbakhsh O et al.Co-infection of invasive pulmonary aspergillosis and cutaneous Fusarium infection in a patient with pyoderma gangrenosum.J Res Med Sci. 2015; 20: 199-203PubMed Google Scholar; Seidel et al., 2020Seidel D Hassler A Salmanton-García J Koehler P Mellinghoff SC Carlesse F et al.Invasive Scedosporium spp. and Lomentospora prolificans infections in pediatric patients: analysis of 55 cases from FungiScope® and the literature.Int J Infect Dis. 2020; 92: 114-122Abstract Full Text Full Text PDF PubMed Scopus (17) Google Scholar). This is the first reported coinfection with Fusarium and Lomentospora. These infections are associated with high mortality, which is related to the host's immune status and inherent antifungal resistance (Nucci and Anaissie, 2007Nucci M Anaissie E. Fusarium infections in immunocompromised patients.Clin Microbiol Rev. 2007; 20: 695-704Crossref PubMed Scopus (728) Google Scholar; Seidel et al., 2020Seidel D Hassler A Salmanton-García J Koehler P Mellinghoff SC Carlesse F et al.Invasive Scedosporium spp. and Lomentospora prolificans infections in pediatric patients: analysis of 55 cases from FungiScope® and the literature.Int J Infect Dis. 2020; 92: 114-122Abstract Full Text Full Text PDF PubMed Scopus (17) Google Scholar). Premature closure and anchoring bias based on microbiologic diagnosis of the initial fungus can delay diagnosis and administration of appropriate antifungal therapy; this reinforces the importance of maintaining a broad differential. Although Occam's razor is the general rule, Hickam's dictum may prevail in immunocompromised hosts. The authors have no competing interests to declare. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.