Clinical and laboratory features of disseminated histoplasmosis during two large urban outbreaks

Disseminated adrenal histoplasmosis in an immunocompetent adult from Nepal: a case report

Introduction

Histoplasmosis is caused by the environmental fungus Histoplasma capsulatum. In immunocompromised patients, histoplasmosis can present as a disseminated infection that can involve the liver, lymph nodes, lungs, and adrenal glands. Disseminated histoplasmosis affecting the adrenal glands in an immunocompetent individual is a rare infection.

Case presentation

A 53-year-old male without HIV complained of weight loss of 15 kg in 6 months. Computed tomography (CT) scan of the abdomen was done, which showed bilateral adrenal gland hyperplasia with hepatosplenomegaly. Endoscopic ultrasound fine needle aspiration of the adrenal gland revealed numerous budding yeast forms of Histoplasma intracellularly within the macrophages. A diagnosis of disseminated adrenal histoplasmosis was made. Liposomal amphotericin B and itraconazole therapy was started.

Discussion

Disseminated histoplasmosis is commonly present in immunocompromised individuals. Immunocompetent individuals may also present with the disseminated form of the disease, which typically involves the adrenal glands. CT scan of the abdomen shows bulky adrenal glands with normal configuration, peripheral enhancement, and central hypodensities due to necrosis and/or hemorrhage. This might be a common presentation in other disseminated infections. Therefore, a definitive visualization of H. capsulatum in tissue specimens is the best method to confirm the diagnosis in a patient.

Conclusion

Physicians must be suspicious of disseminated adrenal histoplasmosis in patients presenting with enlarged adrenal glands, even in immunocompetent individuals who are from endemic regions. Histopathological or cytological evaluation is the best method to establish a diagnosis.

An Interesting Case of Disseminated Histoplasmosis in a Patient With Hemophagocytic Lymphohistiocytosis

Histoplasmosisis a common mycosis in North and Central America caused by Histoplasma capsulatum. Affected patients typically remain asymptomatic. However, in some individuals, histoplasmosis can present as a severe illness, usually occurring in patients with underlying risk factors such as the immunocompromised (e.g., acquired immunodeficiency syndrome (AIDS), treatment with immunosuppressive agents), and the elderly without underlying immunocompromised conditions. Here, we present a case of disseminated histoplasmosis diagnosed as an incidental finding on bone marrow biopsy while treating a hospitalized patient for hemophagocytic lymphohistiocytosis. The patient presented with weight loss, anorexia, fatigue, and generalized weakness. The patient was successfully treated with amphotericin B and eventually transitioned to itraconazole.

Histoplasma capsulatum Complement Fixation and Immunodiffusion Assay Sensitivity in Culture-Confirmed Cases of Histoplasmosis: a 10-Year Retrospective Review (2011 to 2020)

The detection of antibodies against Histoplasma capsulatum remains a frequently relied-on approach to diagnose histoplasmosis. We retrospectively assessed the performances of complement fixation (CF) and immunodiffusion (ID) assays for anti-Histoplasma antibody detection in patients with culture-confirmed histoplasmosis at Mayo Clinic (Rochester, MN) over a 10-year period (2011 to 2020). Among 67 culture-confirmed patients who also had H. capsulatum CF/ID testing ordered, 51 (67.1%) were immunocompromised, 34 (50.7%) had localized disease, and 51 (76.1%) presented with <3 months of symptoms before testing. H. capsulatum CF and/or ID testing was positive in 47 (70.1%) patients, with both assays being positive in 39 cases. CF was positive in 44 (65.7%) patients, with reactivity against both H. capsulatum mycelial and yeast antigens in 30 (68.2%) cases, whereas 11 (25%) and 3 (6.8%) individuals had antibodies to the CF yeast or mycelial antigen only, respectively. H. capsulatum ID was positive in 42 (62.7%) patients, with the presence of the M-band only or the H- and M-bands in 27 (64.3%) and 15 (35.7%) cases, respectively. Among 18 serially tested patients, 12 remained ID and/or CF positive at the final time point (median, 154 days; range, 20 to 480 days). Serial CF testing showed that antibodies to the mycelial antigen serorevert to negative more frequently (6/11) than antibodies to the yeast antigen (2/13). There was no statistically significant difference in antibody positivity relative to patient immune status, degree of disease dissemination, or symptom duration. Serologic testing remains a valuable asset to support the diagnosis of histoplasmosis, particularly when direct detection methods fail to identify an infection.

Hemophagocytic lymphohistiocytosis secondary to progressive disseminated histoplasmosis presenting as cellulitis

Histoplasmosis-associated hemophagocytic lymphohistiocytosis is a rate but lethal disease in immunocompromised hosts. Unusual clinical presentations make diagnosing invasive fungal infection even more challenging. Here we present a case of hemophagocytic lymphohistiocytosis secondary to progressive disseminated histoplasmosis presenting as cellulitis in a patient with systemic lupus erythematous. A high index of suspicion combined with histopathology and molecular diagnostic techniques are important to establish an accurate and timely diagnosis of opportunistic infections in immunocompromised patients.

A comparison of presentations and outcomes of histoplasmosis across patients with varying immune status

Few large cohorts have examined histoplasmosis in both immunocompromised and immunocompetent patients. We describe the differences in presentations and outcomes of histoplasmosis by immune and dissemination status. We assembled a retrospective cohort of adult patients diagnosed with histoplasmosis from 2002 to 2017. Patients were grouped by immune status: people living with HIV (PLWH), patients who were HIV negative but had other-immunocompromise (OIC), and immunocompetent patients. Patients were further classified into asymptomatic lung nodule (ALN), localized and disseminated disease groups, and outcomes were compared across patients by these immune status categories We identified 261 patients with histoplasmosis: 54 (21%) PLWH, 98 (38%) OIC, and 109 (42%) immunocompetent. Disseminated disease was more common among PLWH than among other groups (P < .001). In localized disease, median time from symptom onset to diagnosis was longer in immunocompetent patients than in other groups (P = .012), and was not significant in disseminated disease. The 90-day mortality was higher in PLWH (25%) and OIC (26%) with localized disease compared to the immunocompetent group (4%) (P = .009), but this difference was not seen in disseminated disease. Patients with localized disease had lower 90-day mortality (14%) compared to those with disseminated disease (21%) (P = .034). We conclude that immunocompetent individuals present with fewer typical symptoms, laboratory findings, and radiographic features of Histoplasma infection, leading to potential delays in diagnosis in this group. Despite this, immunocompetent patients have lower 90-day mortality in localized disease, and do not experience increased 90-day mortality in disseminated disease.

LAY SUMMARY

This article examines how the signs and symptoms of histoplasmosis vary by immune status and dissemination status. Immunocompetent patients with localized disease present with fewer typical signs and symptoms, are diagnosed later, but despite this have lower 90-day mortality.

Crohn's disease or histoplasmosis? A case of severe disseminated histoplasmosis mimicking Crohn's disease and literature review

Disseminated histoplasmosis (DH) often mimics other diseases, leading to misdiagnosis and delays in treatment. We present a patient who developed DH after treatment with immunosuppressants for an initial diagnosis of inflammatory bowel disease (IBD). Upon diagnosing her with DH, liposomal amphotericin B was started, and she eventually recovered after a prolonged hospitalization. Intrabdominal histoplasmosis has many similarities with IBD. Treatment with immunosuppressants in undiagnosed histoplasmosis can lead to dissemination with potentially catastrophic results.

Case Report: Hemophagocytic Lymphohistiocytosis Caused by Disseminated Histoplasmosis in a Venezuelan Patient with HIV and Epstein-Barr Virus Reactivation Who Traveled to Japan

We describe a Venezuelan visitor to Japan who was diagnosed with hemophagocytic lymphohistiocytosis (HLH). The patient was also diagnosed with human immunodeficiency virus (HIV) and Epstein-Barr virus infection by the Western blot and polymerase chain reaction (PCR) tests, respectively. The cause of HLH was considered to be these two infections at first; however, the patient did not recover with antiretroviral/anti-herpes virus therapy. Thereafter, diagnosis of disseminated histoplasmosis was confirmed with an antigen detection test, culture, and PCR test of blood, urine, and bone marrow, and the patient improved gradually after the initiation of liposomal amphotericin B. This case highlights the importance of ruling out endemic mycosis as a cause of HLH even if other probable causes exist in patients from endemic areas.

Rabbit Antithymocyte Globulin Causes Blastomyces and Histoplasma Antigenemia

Rabbit antithymocyte globulin (rATG) is known to yield false-positive Histoplasma antigenemia. The fourth generation MiraVista Histoplasma antigen assay was modified to block this effect (MiraVista Diagnostics, Indianapolis, Indiana). We report a case of rATG-induced false-positive Blastomyces and Histoplasma antigenemia in a lung transplant recipient despite modifications of these antigen assays.

Pathologic Features of Infectious Gastritis

This manuscript presents a review of infectious causes of gastritis aimed at the practicing anatomic pathologist. We shall highlight unique histologic findings and clinical attributes that will assist those analyzing endoscopically obtained mucosal biopsies of the stomach or resection specimens.

Sepsis-like histoplasmosis in a kidney transplant patient

Histoplasmosis is a fungus infection that mainly affects immunosuppressed patients. The authors present a case of a kidney transplant recipient who developed sepsis-like histoplasmosis, na atypical but severe manifestation of the disease. The fungus was found in blood and in a skin biopsy, and the treatment with liposomal amphotericin resulted in hepatotoxicity.

Imported endemic mycoses in Spain: Evolution of hospitalized cases, clinical characteristics and correlation with migratory movements, 1997-2014

Endemic mycoses are systemic fungal infections. Histoplasmosis is endemic in all temperate areas of the world; coccidioidomycosis and paracoccidioidomycosis are only present in the American continent. These pathogens are not present in Spain, but in the last years there has been an increase of reported cases due to migration and temporary movements. We obtained from the Spanish hospitals records clinical and demographic data of all hospitalized cases between 1997 and 2014. There were 286 cases of histoplasmosis, 94 of Coccidioidomycosis and 25 of paracoccidioidomycosis. Overall, histoplasmosis was strongly related to HIV infection, as well as with greater morbidity and mortality. For the other mycoses, we did not find any immunosuppressive condition in most of the cases. Although we were not able to obtain data about clinical presentation of all the cases, the most frequently found was pulmonary involvement. We also found a temporal correlation between the Spanish population born in endemic countries and the number of hospitalized cases along this period. This study reflects the importance of imported diseases in non-endemic countries due to migratory movements.

H. capsulatum: A Not-So-Benign Cause of Pericarditis

The common causes of pericarditis and its course are benign in the majority of cases. Thus, further testing is usually not pursued and treatment for a presumptive viral etiology with nonsteroidal agents and steroids has been an accepted strategy. We present a patient with pericarditis who was unresponsive to first-line therapy and was subsequently found to have necrotizing granulomas of the pericardium with extensive adhesions and fungal elements seen on tissue biopsy. Serologic testing confirms active H. capsulatum infection, and he responded well to Itraconazole treatment. In patients with pericarditis who fail standard therapy with NSAIDs and steroids, it is suggested that they undergo thorough evaluation and that histoplasmosis be considered as an etiology, especially in endemic regions.

Histoplasmosis mimicking non-Hodgkin lymphoma in a 40-year-old man with AIDS

In patients with acquired immunodeficiency syndrome (AIDS), advanced immunosuppression is associated with atypical presentation of dermatological conditions. Our patient presented with a single crusted plaque over the lower lip and large tender cervical lymphadenopathy. The enzyme-linked immunosorbent assay for human immunodeficiency virus was found to be positive, and his CD4+ lymphocyte cell count was 4 cells/mm³. The presence of multiple histoplasma spores in the biopsies from the crusted plaque over lip and cervical lymph node helped in the confirmation of the diagnosis of histoplasmosis, and the patient showed significant improvement within two months of treatment with conventional injection amphotericin B initially followed by oral itraconazole.

The Simultaneous Occurrence of Histoplasmosis and Cryptococcal Fungemia: A Case Report and Review of the Literature

Simultaneous infections with Cryptococcus neoformans and Histoplasma capsulatum are rare and typically occur in immunocompromised individuals, particularly AIDS patients. Because both of those fungi can spur the development of latent infections, it is generally unknown which organism was first present. The diagnosis of one fungus can hide the diagnosis of the other, leading to underdiagnoses and poor prognosis. We report a case of C. neoformans and H. capsulatum co-infection. We also performed a systematic review of the literature. Our patient, a 69-year-old HIV-negative man, presented with a 9-month history of a productive cough, dyspnea and wheezing. His history showed chronic obstructive pulmonary disease and type II diabetes mellitus (DM). Pulmonary lesions of unidentified etiology were noted. Cryptococcal involvement of the central nervous system was confirmed, and C. neoformans and H. capsulatum were also isolated from blood cultures. In the literature, we found ten cases of simultaneous histoplasmosis and cryptococcosis. Including our patient, all of the cases were located in North America and Latin America, except for two, one Indian and one African diagnosed in France. AIDS was the main predisposing factor, followed by DM and age >60 years. Several diagnostic methods were employed. A blood culture and bronchoalveolar lavage (BAL) culture resulted in the growth of C. neoformans in most of the cases. H. capsulatum was more often detected in BAL and bone marrow cultures. Although co-infection by these pathogens is severe, it can be cured if it is diagnosed and treated early. We emphasized the importance of clinical suspicion and differential diagnosis of systemic mycoses.

New clinical phenotypes of fungal infections in special hosts

Incidence of invasive fungal infections increases over time with the rise in at-risk populations; in particular, patients with acquired immunodeficiencies due to immunosuppressive therapies such as anti-tumour necrosis factor-α (TNF-α) treatment, cirrhosis or burns. Some primary immunodeficiencies (PID) can also predispose selectively to invasive fungal diseases. Conversely, some atypical fungal diseases can reveal new PID. Deep dermatophytosis, Candida central nervous system infections or gastrointestinal disease, or disseminated phaeohyphomycosis-revealed CARD9 deficiency. Most patients with inherited chronic mucocutaneous candidiasis were found to carry STAT1 gain-of-function mutations. The spectrum of fungal susceptibility and clinical presentation varies according to the PID. Among acquired immunodeficiencies, immunosuppressive treatments such as TNF-α blocker therapy, which has revolutionized autoimmune disorder treatment, may be complicated by endemic mycosis, aspergillosis, pneumocystosis or cryptococcosis. Burn patients with damaged skin barrier protection are susceptible to severe Candida infections and filamentous fungal infections (such as Aspergillus spp., Mucorales). Moreover, patients with cirrhosis are at increased risk of fungal infections. Therefore, physicians should think of any potential underlying acquired or inherited immunodeficiency in a patient developing an atypical fungal infection, or of a potential fungal disease in the context of an atypical presentation in specific hosts.

Update on the spectrum of histoplasmosis among hispanic patients presenting to a New York City municipal hospital: A contemporary case series

Histoplasma capsulatum is the most common endemic mycosis worldwide. Although most of the globe's largest urban hubs fall outside this organism's regions of endemicity, clinicians practicing in a metropolis like New York City or Los Angeles must nevertheless remain vigilant for histoplasmosis because of the large immigrant population that is served by its hospitals. H. capsulatum infection ranges from asymptomatic pulmonary infection to life-threatening diffuse pneumonia with dissemination. The early years of the AIDS epidemic first introduced U.S. clinicians working in areas previously unfamiliar with histoplasmosis to newly immunocompromised patients from endemic regions presenting with disseminated H. capsulatum originally acquired in their home countries. Improvement in HIV prevention and therapeutics has reduced the frequency of such cases. Herein we report three cases of histoplasmosis encountered in our New York City institution over the last three years to emphasize that awareness of this infection remains mandatory for the frontline urban clinician.

Histoplasmosis infections worldwide: thinking outside of the Ohio River valley

In the United States, histoplasmosis is generally thought to occur mainly in the Ohio and Mississippi River Valleys, and the classic map of histoplasmosis distribution reflecting this is second nature to many U.S. physicians. With the advent of the HIV pandemic reports of patients with progressive disseminated histoplasmosis and AIDS came from regions of known endemicity, as well as from regions not thought to be endemic for histoplasmosis throughout the world. In addition, our expanding armamentarium of immunosuppressive medications and biologics has increased the diagnosis of histoplasmosis worldwide. While our knowledge of areas in which histoplasmosis is endemic has improved, it is still incomplete. Our contention is that physicians should consider histoplasmosis with the right constellations of symptoms in any febrile patient with immune suppression, regardless of geographic location or travel history.

A complementary tool for management of disseminated Histoplasma capsulatum var. capsulatum infections in AIDS patients

In South America, disseminated histoplasmosis due to Histoplasma capsulatum var. capsulatum (H. capsulatum), is a severe and frequent opportunistic infection in AIDS patients. In areas outside the USA where specific-Histoplasma antigen detection is not available, the diagnosis is difficult. With the galactomannan antigen (GM) detection, a test commonly used for invasive aspergillosis diagnosis, there is a cross-reactivity with H. capsulatum that can be helpful for the diagnosis of histoplasmosis. The aim of this study was to evaluate the GM detection for the diagnosis of disseminated histoplasmosis in AIDS patients. The performance of the GM detection was evaluated with serum collected in French Guiana where H. capsulatum is highly endemic. Sera from AIDS patients with disseminated histoplasmosis occurring from 2002 to 2009 and from control HIV-positive patients without histoplasmosis were tested with the GM detection and Histoplasma-specific antibody detection (IEP). In 39 AIDS patients with proven disseminated histoplasmosis, the sensitivity of the Histoplasma IEP was only 35.9% and was linked to the TCD4+ lymphocyte level. For the GM detection, the sensitivity (Se) was 76.9% and specificity (Sp) was 100% with the recommended threshold for aspergillosis diagnosis (0.5). The test was more efficient with a threshold of 0.4 (Se: 0.82 [95% CI: 0.66-0.92], Sp: 1.00 [95% CI: 0.86-1.00], LR+: >10, LR-: 0.18). This study confirms that the GM detection can be a surrogate marker for the diagnosis of disseminated histoplasmosis in AIDS patients in endemic areas where Histoplasma EIA is not available.

Histoplasmosis infection in patients with rheumatoid arthritis, 1998-2009

Background

Patients with rheumatic diseases including rheumatoid arthritis (RA) are at increased risk for infections related to both the disease and its treatments. These include uncommonly reported infections due to histoplasmosis.

Methods

Medical record review of all patients with a diagnosis of RA who developed new histoplasmosis infection in an endemic region between Jan 1, 1998 and Jan 30, 2009 and who were seen at Mayo Clinic in Rochester, Minnesota was performed.

Results

Histoplasmosis was diagnosed in 26 patients. Most patients were on combination therapies; 15 were on anti-tumor necrosis factor (anti-TNF) agents, 15 on corticosteroids and 16 on methotrexate. Most received more than 6 months of itraconazole and/or amphotericin treatment. Two patients died of causes unrelated to histoplasmosis. Anti-TNF treatment was restarted in 4/15 patients, with recurrence of histoplasmosis in one.

Conclusions

In this largest single center series of patients with RA and histoplasmosis in the era of immunomodulatory therapy, we found that most patients had longstanding disease and were on multiple immunomodulatory agents. Most cases were pulmonary; typical signs and symptoms of disease were frequently lacking.

Epidemiology of endemic systemic fungal infections in Latin America

Although endemic mycoses are a frequent health problem in Latin American countries, clinical and epidemiological data remain scarce and fragmentary. These mycoses have a significant impact on public health, and early diagnosis and appropriate treatment remain important. The target population for endemic disease in Latin America is mostly represented by low-income rural workers with limited access to a public or private health system. Unfortunately, diagnostic tools are not widely available in medical centers in Latin America; consequently, by the time patients are diagnosed with fungal infection, many are already severely ill. Among immunocompromised patients, endemic mycoses usually behave as opportunistic infections causing disseminated rather than localized disease. This paper reviews the epidemiology of the most clinically significant endemic mycoses in Latin America: paracoccidioidomycosis, histoplasmosis, and coccidioidomycosis. The burdens of disease, typically affected populations, and clinical outcomes also are discussed.

"Ohio River valley fever" presenting as isolated granulomatous hepatitis: a case report

Histoplasmosis is endemic to the midwestern and east central states in the United States near the Mississippi and the Ohio River valleys. Ninety-nine percent of patients exposed to histoplasmosis develop only subclinical infection. Liver involvement as a part of disseminated histoplasmosis is well known; however, isolated hepatic histoplasmosis without any other stigmata of dissemination is extremely rare and the literature is limited to only two case reports. We present a rare case of isolated granulomatous hepatitis due to histoplasmosis in a 35-year-old female with dermatomyositis receiving low-dose prednisone and methotrexate. There was no evidence of fungal dissemination elsewhere. High clinical suspicion is critical for early diagnosis and treatment.

Infectious diseases and the liver

The liver plays an important role in host defense against invasive microorganisms. The effect of microbial pathogens on the liver can vary greatly, presenting with a wide variety of manifestations from asymptomatic increases in aminotransaminases, acute liver failure, hepatic fibrosis, and cirrhosis. In evaluating the liver manifestations of a potential infectious pathogen, diagnosis of some of the less common infectious pathogens is dependent on a high level of suspicion and recognition of some of the key diagnostic clues. Successful diagnosis can only be accomplished through a careful history, including travel and exposures, physical examination, and appropriate microbiologic studies. This article reviews the involvement of the liver during systemic infections with organisms that are not considered to be primarily hepatotropic.

Common and emerging fungal pulmonary infections

Fungal pulmonary infections are becoming more prevalent as a consequence of the rising prevalence of immunocompromised patients. Besides ubiquitous opportunistic fungi such as Aspergillus spp and geographically delimited mycoses, fungi that were previously thought to be of uncertain pathogenicity, such as hyaline and dematiaceous molds, are increasingly being diagnosed as the causes of invasive disease in profoundly immunosuppressed hosts. Overall progress in the clinical management of fungal pulmonary infections has been slow compared with other areas of infectious diseases. However, recent encouraging advances in fungal diagnostics and therapeutics have resulted in improved clinical outcomes, particularly in vulnerable patient populations such as solid organ or allogeneic hematopoietic stem cell transplant recipients. This article provides an overview of endemic mycoses and other emerging fungal pulmonary infections. Recent developments in terms of the diagnosis and clinical management of these infections are also discussed.

Treatment of endemic mycoses

The endemic mycoses are a diverse group of diseases caused by thermally dimorphic fungi. While they share many characteristics, each has unique aspects with regards to their clinical course, diagnosis and management. Diagnosis may be difficult and delayed owing to the varied manifestations and wide differential diagnosis. Historically, treatment has been with amphotericin B, which has been limited by its significant toxicity. The advent of the azole class of medications has allowed for safer alternatives to amphotericin B. The azoles have become the mainstay of treatment for many, if not most, forms of these diseases. Guidelines have been released for the management of each of the North American endemic mycoses; however, many questions remain as to the best strategies for the diagnosis and management of various manifestations of these diseases.

Epidemiology of invasive mycoses in North America

The incidence of invasive mycoses is increasing, especially among patients who are immunocompromised or hospitalized with serious underlying diseases. Such infections may be broken into two broad categories: opportunistic and endemic. The most important agents of the opportunistic mycoses are Candida spp., Cryptococcus neoformans, Pneumocystis jirovecii, and Aspergillus spp. (although the list of potential pathogens is ever expanding); while the most commonly encountered endemic mycoses are due to Histoplasma capsulatum, Coccidioides immitis/posadasii, and Blastomyces dermatitidis. This review discusses the epidemiologic profiles of these invasive mycoses in North America, as well as risk factors for infection, and the pathogens' antifungal susceptibility.

Unusual otolaryngological manifestations of certain systemic bacterial and fungal infections in children

OBJECTIVE

Systemic bacterial and fungal infections may sometimes present local manifestations within otolaryngological district whose early detection may be useful in establishing a correct diagnosis and more appropriate treatment. This paper reviews certain systemic bacterial and fungal diseases presenting ENT manifestations in the pediatric population from an otolaryngological perspective.

METHODS

A medline searching for specific issues was performed in order to achieve more information as possible with regards to ENT manifestation of systemic bacterial and fungal infections. Limits for pediatric age were used. Two separate sections for bacterial and fungal disease are included. The section on systemic bacterial infections considers cat-scratch disease, Lyme borreliosis, actinomycosis, Lemierre's syndrome and congenital syphilis, and the section on systemic fungal infections includes candidiasis, aspergillosis and histoplasmosis.

CONCLUSIONS

Pediatricians and ear, nose and throat (ENT) specialists, approaching head and neck disorders in children, should therefore consider them among the possible differential diagnoses. This means that physicians need to recognize the first head and neck manifestations of systemic infections promptly in order to be able to treat them efficaciously and avoid the dangerous systemic spreading of the infective process.

[Primary cutaneous histoplasmosis: case report on an immunocompetent patient and review of the literature]

This report describes a case of primary cutaneous histoplasmosis in a 45-year-old male. The presentation consisted of an erythematous nodule on the back of the right hand, accompanied by nontender regional lymphadenomegaly that developed following local trauma that occurred during military training in a tunnel inhabited by bats. Histological examination of a biopsy specimen from the skin lesion showed granulomatous infiltrate, but did not show fungal elements. Culturing of this material, incubated in Sabouraud agar, showed growth of Histoplasma capsulatum. No evidence of systemic involvement or immunosuppression was found. Treatment with 400 mg/day of itraconazole orally for six months resulted in complete remission of the lesion, which was maintained one year after the end of the treatment.

Fungal Infections

The incidence of invasive fungal infections has increased dramatically over the past two decades, mostly due to an increase in the number of immunocompromised patients.1–4 Patients who undergo chemotherapy for a variety of diseases, patients with organ transplants, and patients with the acquired immune deficiency syndrome have contributed most to the increase in fungal infections.5 The actual incidence of invasive fungal infections in transplant patients ranges from 15% to 25% in bone marrow transplant recipients to 5% to 42% in solid organ transplant recipients.6,7 The most frequently encountered are Aspergillus species, followed by Cryptococcus and Candida species. Fungal infections are also associated with a higher mortality than either bacterial or viral infections in these patient populations. This is because of the limited number of available therapies, dose-limiting toxicities of the antifungal drugs, fewer symptoms due to lack of inflammatory response, and the lack of sensitive tests to aid in the diagnosis of invasive fungal infections.1 A study of patients with fungal infections admitted to a university-affiliated hospital indicated that community-acquired infections are becoming a serious problem; 67% of the 140 patients had community-acquired fungal pneumonia.8

Systemic histoplasmosis: a 15-year retrospective institutional review of 111 patients

To our knowledge, an institutional review of systemic histoplasmosis has not been conducted in the United States since the major outbreaks in Indianapolis in 1978-4982. We conducted a retrospective review of all patients with systemic histoplasmosis diagnosed at Mayo Clinic over a 15-year period. The case definitions employed were based on an international consensus statement by the European Organization for Research and Treatment of Cancer/Invasive Fungal Infections Cooperative Group (EORTC/IFICG) and the National Institute of Allergy and Infectious Diseases Mycoses Study Group (MSG). One hundred eleven patients with systemic histoplasmosis were identified between January 1, 1991, and December 31, 2005. Of these, 78 patients had disseminated histoplasmosis and 55 patients had Histoplasma capsulatum fungemia. The mean age of patients was 55 years, 66% were male, and 98% were white. Fifty-nine percent of patients were immunocompromised. Fever was the most frequently reported symptom (63%), followed by respiratory complaints (43%) and weight loss (37%). The peripheral white blood cell count was <3000 cells/mm in 28%, hemoglobin was <10 g/dL in 29%, and platelet count was <150,000 cells/mm in 41% of patients. Liver enzymes were elevated (alanine aminotransferase >60 U/L in 39%, aspartate aminotransferase >60 U/L in 27%), alkaline phosphatase was >200 U/L in 55%, and albumin was <3.5 g/dL in 70%. Serologic and histopathologic examinations were each positive in 75% of cases, Histoplasma urine antigen screening was positive in 80%, and H. capsulatum was culture positive in 84%. Forty-seven percent of patients were sequentially treated with an amphotericin B-containing product followed by itraconazole, 31% received itraconazole alone, and 7% received an amphotericin B-containing product only. Another 13% of patients did not receive antifungal treatment, and the remaining 2% did not have treatment data available. Sixty percent of patients required hospitalization, and in hospital mortality was 6% with a median survival time of 61 days. The relapse rate was 9%, with a median relapse-free survival of 857 days. Systemic histoplasmosis should be suspected in patients who have lived in endemic areas with fever, bone marrow suppression, and elevated hepatic enzymes, particularly if they are immunocompromised. Evaluation including a combination of Histoplasma serologic screening, urine antigen assay, and fungal culture will secure the diagnosis in most cases.

Production and evaluation of reagents for detection of Histoplasma capsulatum antigenuria by enzyme immunoassay

The detection of urinary Histoplasma capsulatum polysaccharide antigen (HPA) by enzyme immunoassay (EIA) has proven useful for the presumptive diagnosis of histoplasmosis in AIDS patients. Assay limitations include (i) detection of a largely uncharacterized antigen and (ii) difficulty in reproducibly generating antibodies for use in the EIA. To improve antibody production for use in this test and to better understand the antigen being detected, we compared rabbit antibodies elicited using various immunization schedules, routes, and H. capsulatum-derived antigens. Antibodies were evaluated by EIA for their ability to detect purified H. capsulatum C antigen (C-Ag) and antigenuria. Reported as enzyme immunoassay (EI) units (the A(450) with antigen divided by the A(450) without antigen), results demonstrated that intravenous immunization of rabbits with whole, killed yeast-phase cells (yeast-i.v. regimen) produced antibodies giving the highest EI values in the C-Ag EIA (mean EI units +/- standard deviation, 14.9 +/- 0.6 versus 6.4 +/- 0.4 for rabbits immunized with C-Ag versus 2.4 +/- 0.3 for all other regimens combined). Yeast-i.v. antibodies were highly sensitive for the detection of antigenuria in patients with histoplasmosis, as shown by the following results: 12/12 patients compared to 10/12, 6/12, 3/12, and 3/12, respectively, for antibodies from rabbits immunized with (i) C-Ag; (ii) whole, killed yeast-phase cells administered subcutaneously and intramuscularly; (iii) yeast-phase culture filtrates; and (iv) HPA-positive urine. Rabbits immunized using the yeast-i.v. regimen also gave higher peak antibody titers than rabbits immunized by any other regimen (P < 0.03), and their antibodies were most comparable in reactivity to antibodies produced for use in the standard HPA-EIA test (P < 0.001). Therefore, rabbits immunized using the yeast-i.v. regimen produced the most sensitive antibodies with the highest titers for detection of C-Ag and antigenuria in histoplasmosis patients.

Improvements in diagnosis of histoplasmosis

Understanding the uses and limitations of a battery of laboratory methods is essential to diagnose histoplasmosis. Antigen detection and serology are valuable adjuncts to histopathology and culture. Improvements incorporated into the second-generation Histoplasma antigen assay have increased its sensitivity and specificity for diagnosis of histoplasmosis. More recently, the antigen assay has been modified to provide quantitation, which improves reproducibility and facilitates monitoring antigen clearance during treatment. Furthermore, detection of antigen in bronchoalveolar lavage fluid increases the sensitivity for diagnosis of pulmonary histoplasmosis. Serological tests for antibodies are also useful, but may be falsely negative in immunosuppressed patients. In addition, elevated antibody titres persist for several years following initial infection, complicating their interpretation. Although histopathology may provide for rapid diagnosis, its sensitivity is < 50% in patients with disseminated disease and even lower in pulmonary histoplasmosis. Polymerase chain reaction has been described, but sensitivity is less than that of histopathology. Culture, although highly specific, has notable limitations, including insensitivity, a need for invasive procedures and delayed growth. This review provides the background for understanding the role of a battery of diagnostic methods in histoplasmosis. Tests facilitating a rapid diagnosis are expected to improve the outcome in patients with severe disease.

American histoplasmosis in developing countries with a special focus on patients with HIV: diagnosis, treatment, and prognosis

PURPOSE OF REVIEW

Histoplasmosis due to Histoplasma capsulatum var capsulatum is a frequent systemic fungal infection in the Americas. Diagnostic and therapeutic options differ between North and South America. Disseminated histoplasmosis is an AIDS-defining infection. Prognostic factors of potentially severe presentations must be evaluated in order to facilitate the initial therapeutic choice.

RECENT FINDINGS

Patients with HIV with disseminated infections presenting with severe pulmonary and renal impairment have a poor prognosis. Cutaneous presentations are more frequent in HIV patients in South America than in North America. A murine model has shown that South American isolates have a greater virulence that North American isolates. These differences are due in part to diagnostic delays in resource-poor countries.

SUMMARY

Direct examination of May-Grünwald-Giemsa-stained smears or tissues in suspected histoplasmosis is a simple means of confirming the diagnosis in resource-poor settings. Studies of prognostic factors should further refine indication criteria to guide first-line treatment choice between amphotericin B and itraconazole. The association of tuberculosis and histoplasmosis is frequent in HIV patients and presents diagnostic and therapeutic challenges that may be difficult to resolve in resource-poor settings. It is important that affordable generic drugs for treating histoplasmosis be made widely available in resource-poor countries.

Chest Pain Resulting From Histoplasmosis Pericarditis

Histoplasmosis is an endemic disease in many regions of the United States. Physicians must be aware of the clinical syndromes and take advantage of epidemiologic clues when diagnosing histoplasmosis pericarditis. Clinicians must also be familiar with the uses and limitations of a battery of serologic and mycologic tests. Finally, further clinical trials are needed to study the role of antifungal therapy in the treatment of histoplasmosis pericarditis.

Histoplasmosis: a review for clinicians from non-endemic areas

Histoplasmosis is an important systemic mycosis in the Americas, Asia, and Africa. Increasingly cases are recognised in nonendemic areas. Proper management requires recognition of the clinical syndromes caused by Histoplasma capsulatum infection, familiarity with the uses and limitations of the diagnostic tests, an understanding of the indications for treatment and role of specific antifungal agents. This review will address these issues with the goal of providing physicians in non-endemic areas sufficient information to suspect, diagnose, and treat patients with histoplasmosis.

Disseminated histoplasmosis in a liver transplant recipient

A 61-yr-old liver transplant recipient presented with abdominal cramping and nonbloody diarrhea resulting in orthostasis. Multiple ulcerations throughout the colon were seen during endoscopy, and biopsies from the ulcer edges revealed histoplasmosis. Treatment with a course of itraconazole improved the diarrhea. The patient later presented with pericarditis and symptomatic pleural effusions, the latter of which was confirmed to be a result of disseminated histoplasmosis. Treatment with amphotericin B led to resolution. Histoplasmosis should be considered in liver transplant patients with diarrhea and large ulcers in the colon. The presence of disseminated histoplasmosis should be ruled out once colonic histoplasmosis has been diagnosed.

Isolated central nervous system histoplasmosis in immunocompetent hosts: a series of 11 cases

Histoplasmosis of the central nervous system occurs in a significant percentage of patients with Histoplasma capsulatum infection, but has usually been described in association with immunosuppression and/or disseminated histoplasmosis. We aim to review the clinical and laboratory features of isolated histoplasmosis of the central nervous system in the immunocompetent host by presenting a series of 11 cases with this condition. Most of these patients presented with headache, meningeal irritation signs and mental status changes, comprising a somewhat different picture from that described in immunosuppressed patients. Moreover, almost all patients had signs of ventricular dilatation in neuroimaging studies, and 8 of the 11 patients had a ventriculoperitoneal shunt at the time of diagnosis, suggesting hydrocephalus to be an important feature of this condition and/or the possibility of shunt infection by the fungus. Immunodiffusion analysis of the cerebrospinal fluid appeared to be the most efficient way to reach the diagnosis and should be considered in immunocompetent patients with chronic lymphocytic meningitis, especially in those who have ventricular shunt or live in endemic areas of Histoplasma capsulatum.