Pediatric Histoplasmosis in an Area of Endemicity: A Contemporary Analysis

Thrombotic Microangiopathy Due to Progressive Disseminated Histoplasmosis in a Child With Down Syndrome and Acute Lymphoblastic Leukemia

Histoplasmosis, a common mycosis in the south-central United States, may be life threatening in immunocompromised patients. We describe a 4-year-old female with Down syndrome and acute lymphoblastic leukemia who developed hemolytic anemia, thrombocytopenia, and renal failure, consistent with thrombotic microangiopathy. Bone marrow biopsy revealed non-necrotizing granulomas with GMS staining demonstrating budding yeast. Serum Histoplasma antigen testing was positive, providing further evidence for the diagnosis of progressive disseminated histoplasmosis. Treatment with amphotericin B, plasma exchange, and ventilator, vasopressor, and renal replacement support led to a full recovery. Providers should have a low threshold for histoplasmosis testing in ill immunocompromised patients, who are at greater risk for infection-related morbidity.

A 14-Year-Old Female With Chest Mass, Shortness of Breath, and Hypertension

BACKGROUND

A previously healthy 14-year-old girl was evaluated in the emergency department (ED) with 2 months of shortness of breath and fatigue.

METHODS

She initially presented to her primary pediatrician, where a complete blood count was only significant for mild anemia, thyroid function tests were normal, and a chest x-ray revealed a chest mass. This prompted her primary pediatrician to order a computed tomography scan and refer to the ED.

RESULTS

Her computed tomography scan confirmed a mediastinal mass versus necrotic lymphadenopathy. Her initial physical exam was unremarkable, except for hypertension. From the ED, she was admitted to the pediatric hospital medicine service. Infectious disease, oncology, and nephrology services were consulted to guide diagnostic evaluation.

CONCLUSIONS

Eventually, during her hospitalization, further history and workup led to a definitive diagnosis.

Intramedullary histoplasmosis lesion in children: A case report

Background:

Histoplasmosis is a fungal disease endemic in some regions of the United States of America, Canada, and Latin America. The geographic characteristics, humidity, soil, and climate are responsible for such distribution. In Brazil, there are case reports of histoplasmosis throughout its territory, being considered an endemic region. It is considered an opportunistic disease, affecting mostly immunocompromised patients. To the present date, scientific publications dealing with pediatric cases of histoplasmosis are restricted to case series. Spinal cord injuries caused by histoplasmosis are rare, even in the adult population, being described in few studies.

Case Description:

The present report deals with a 4-year-old patient, from the southeast region of Brazil, who started a condition of fever, weight loss, cervicobrachialgia, and symmetrical tetraparesis, with evolution over 2 months. In the diagnostic investigation, she was found to have primary immunodeficiency and neuroimaging examinations showed a cervical spinal cord lesion at the level of C4-C6. The anatomopathological diagnosis of histoplasmosis was possible after surgery for decompression and biopsy of the lesion.

Conclusion:

According to our research, there are no reports in the literature that address the situation of spinal cord compression syndrome due to histoplasmosis in the pediatric population.

Histoplasmosis in African children: clinical features, diagnosis and treatment

Most of the reviews on histoplasmosis documented in literature have been in the adult population. Very few studies highlight the peculiarities associated with histoplasmosis in Africa especially in the pediatric population. This review addresses the above concerns with clinical summaries and diagnosis of some case reports of histoplasmosis in African children. We highlighted 44 case reports of histoplasmosis in African children (1950–2021) distributed across Western Africa (38.6%, n = 17), Eastern Africa (9.1%, n = 4), Southern Africa (9.1%, n = 4), and Central Africa (43.2%, n = 19). No case report was found from Northern Africa. The age range was 1–17 years, with a mean of 9.2. Of the 44 case reports, 8 cases (18.2%, 8/44) were caused by Histoplasma capsulatum var capsulatum, 33 cases (75%, 33/44) were caused by Histoplasma capsulatum var duboisii, and specie identification was not found in 3 cases. Only three (6.8%) cases were HIV positive; 56.8% (25/44) were disseminated histoplasmosis, pulmonary histoplasmosis accounted for just one case (2.3%, 1/44). Extrapulmonary presentation included skin lesions (ulcers, fistulas, nodules, patches, pigmentations, papules, and abscesses), bone lesions, osteoarthritis, and fractures. The commonest sites affected were skin ( n = 29, 65.9%), bones ( n = 20, 45.5%), and lymph nodes ( n = 15, 34.1%). Histopathology was the commonest diagnostic method ( n = 33, 75%). Amphotericin B was first-line therapy in 45.5% of the cases ( n = 20) followed by ketoconazole (20.5%, n = 9); 27 cases (61.4%) had favorable outcomes, 8 cases (18.2%) had fatal outcomes, while in 9 cases, the outcome was not revealed. This review revealed several cases of histoplasmosis misdiagnosed as other conditions including tuberculosis ( n = 3, 6.8%), pneumonia ( n = 1, 2.3%), cancers ( n = 4, 9.1%), nephritic syndrome ( n = 1, 2.3%), leishmaniasis ( n = 1, 2.3%), and hyperreactive malarial splenomegaly syndrome ( n = 1, 2.3%). In addition, histoplasmosis was not considered in some case reports even when symptoms were suggestive. Diagnosis of histoplasmosis was made at autopsy with postmortem findings suggestive of histoplasmosis ( n = 3, 6.8%). This report highlights the need for a paradigm shift on the part of pediatricians in Africa. They need to look beyond clinical conditions considered common in our environment for this age group and evaluate for other diseases including histoplasmosis.

Case report: Disseminated histoplasmosis in a renal transplant recipient from a non-endemic region

Histoplasmosis is the most common endemic fungal infection in the USA. The majority of cases are asymptomatic and have clear exposure to endemic regions. In contrast, we present an adolescent immunocompromised patient with systemic and relatively non-specific symptoms including abdominal pain, weight loss, lower extremity edema, and scabbing skin lesions, without known exposure to endemic areas for histoplasmosis. Histologic analysis of gastrointestinal and skin biopsies eventually revealed a diagnosis of disseminated histoplasmosis; the patient was successfully treated with amphotericin B followed by itraconazole maintenance therapy. Ultimately, a high bar of suspicion for fungal disease must be maintained in immunosuppressed individuals even without apparent exposure history to endemic areas. This case report serves as a valuable reference for practitioners evaluating differential diagnosis of infections in immunocompromised patients.

Histoplasmosis in Children; HIV/AIDS Not a Major Driver

The classification of histoplasmosis as an AIDS-defining illness has largely attributed its occurrence in people to the presence of HIV/AIDS especially in Africa. Prior to the advent of the HIV/AIDS epidemic, several cases of histoplasmosis were documented both in the pediatric and adult populations. Our review revealed 1461 reported cases of pediatric histoplasmosis globally in the last eight decades (1939-2021). North America (n = 1231) had the highest number of cases, followed by South America (n = 135), Africa (n = 65), Asia (n = 26) and Europe (n = 4). Histoplasmosis was much more common in the non-HIV pediatric population (n = 1418, 97.1%) compared to the HIV population. The non-HIV factors implicated were, childhood malignancies (n = 207), such as leukemias and lymphomas as well as their treatment, lung diseases (n = 7), environmental exposures and toxins (n = 224), autoimmune diseases (n = 12), organ transplants (n = 12), long-term steroid therapy (n = 3), the use of immunosuppressive drugs such as TNF-alpha inhibitors (n = 7) malnutrition (n = 12), histiocytosis (n = 3), Hyper immunoglobulin M and E syndromes (n = 15, 1.2%), pancytopenia (n = 26), diabetes mellitus (n = 1) and T-cell deficiency (n = 21). Paediatricians should always consider or rule out a diagnosis of histoplasmosis in children presenting with symptoms suggestive of the above clinical conditions.

Reintroduction of immunosuppressive medications in pediatric rheumatology patients with histoplasmosis: a case series

BACKGROUND

Children with rheumatic diseases (cRD) receiving immunosuppressive medications (IM) are at a higher risk for acquiring potentially lethal pathogens, including Histoplasma capsulatum (histoplasmosis), a fungal infection that can lead to prolonged hospitalization, organ damage, and death. Withholding IM during serious infections is recommended yet poses risk of rheumatic disease flares. Conversely, reinitiating IM increases risk for infection recurrence. Tumor necrosis factor alpha inhibitor (TNFai) biologic therapy carries the highest risk for histoplasmosis infection after epidemiological exposure, so other IM are preferred during active histoplasmosis infection. There is limited guidance as to when and how IM can be reinitiated in cRD with histoplasmosis. This case series chronicles resumption of IM, including non-TNFai biologics, disease-modifying anti-rheumatic drugs (DMARDs), and corticosteroids, following histoplasmosis among cRD.

CASE PRESENTATION

We examine clinical characteristics and outcomes of 9 patients with disseminated or pulmonary histoplasmosis and underlying rheumatic disease [juvenile idiopathic arthritis (JIA), childhood-onset systemic lupus erythematosus (cSLE), and mixed connective tissue disease (MCTD)] after reintroduction of IM. All DMARDs and biologics were halted at histoplasmosis diagnosis, except hydroxychloroquine (HCQ), and patients began antifungals. Following IM discontinuation, all patients required systemic or intra-articular steroids during histoplasmosis treatment, with 4/9 showing Cushingoid features. Four patients began new IM regimens [2 abatacept (ABA), 1 HCQ, and 1 methotrexate (MTX)] while still positive for histoplasmosis, with 3/4 (ABA, MTX, HCQ) later clearing their histoplasmosis and 1 (ABA) showing decreasing antigenemia. Collectively, 8/9 patients initiated or continued DMARDs and/or non-TNFai biologic use (5 ABA, 1 tocilizumab, 1 ustekinumab, 3 MTX, 4 HCQ, 1 leflunomide). No fatalities, exacerbations, or recurrences of histoplasmosis occurred during follow-up (median 33 months).

CONCLUSIONS

In our cohort of cRD, histoplasmosis course following reintroduction of non-TNFai IM was favorable, but additional studies are needed to evaluate optimal IM management during acute histoplasmosis and recovery. In this case series, non-TNFai biologic, DMARD, and steroid treatments did not appear to cause histoplasmosis recurrence. Adverse events from corticosteroid use were common. Further research is needed to implement guidelines for optimal use of non-TNFai (like ABA), DMARDs, and corticosteroids in cRD following histoplasmosis presentation.

Paediatric Histoplasmosis 2000-2019: A Review of 83 Cases

Histoplasmosis is an endemic fungal infection that is confined to specific geographical regions. Histoplasma spp. are primary pathogens that cause disease in both immunocompetent and immunocompromised patients, ranging from a single-organ (mostly affecting the lungs) infection to life-threatening disseminated disease. Knowledge about the clinical epidemiology relies on data from adult populations; little is known about the patient and disease characteristics in the paediatric population. Therefore, a structured review of published cases of paediatric histoplasmosis between 2000 and 2019 was performed. A literature search of PubMed was conducted and the epidemiological and clinical data from 83 cases were analysed. The mean age at presentation was 9.5 ± 5.5 years, and 51% were girls. Two-thirds of the children were immunocompromised. The majority of children presented with disseminated disease. The most frequently observed clinical symptoms were respiratory symptoms, alongside non-specific systemic features, including fever, myalgia, fatigue and weight loss. The mortality rate was 11%. Histoplasmosis affects children of any age. Being immunocompromised is a risk factor for severe and disseminated disease. The lack of specific presenting features leads to underreporting and delay in diagnosis. To improve the recognition and outcome of histoplasmosis in childhood, increased awareness and surveillance systems are warranted.

Advances in Understanding Human Genetic Variations That Influence Innate Immunity to Fungi

Fungi are ubiquitous. Yet, despite our frequent exposure to commensal fungi of the normal mammalian microbiota and environmental fungi, serious, systemic fungal infections are rare in the general population. Few, if any, fungi are obligate pathogens that rely on infection of mammalian hosts to complete their lifecycle; however, many fungal species are able to cause disease under select conditions. The distinction between fungal saprophyte, commensal, and pathogen is artificial and heavily determined by the ability of an individual host's immune system to limit infection. Dramatic examples of commensal fungi acting as opportunistic pathogens are seen in hosts that are immune compromised due to congenital or acquired immune deficiency. Genetic variants that lead to immunological susceptibility to fungi have long been sought and recognized. Decreased myeloperoxidase activity in neutrophils was first reported as a mechanism for susceptibility to Candida infection in 1969. The ability to detect genetic variants and mutations that lead to rare or subtle susceptibilities has improved with techniques such as single nucleotide polymorphism (SNP) microarrays, whole exome sequencing (WES), and whole genome sequencing (WGS). Still, these approaches have been limited by logistical considerations and cost, and they have been applied primarily to Mendelian impairments in anti-fungal responses. For example, loss-of-function mutations in CARD9 were discovered by studying an extended family with a history of fungal infection. While discovery of such mutations furthers the understanding of human antifungal immunity, major Mendelian susceptibility loci are unlikely to explain genetic disparities in the rate or severity of fungal infection on the population level. Recent work using unbiased techniques has revealed, for example, polygenic mechanisms contributing to candidiasis. Understanding the genetic underpinnings of susceptibility to fungal infections will be a powerful tool in the age of personalized medicine. Future application of this knowledge may enable targeted health interventions for susceptible individuals, and guide clinical decision making based on a patient's individual susceptibility profile.