Pulmonary Histoplasma Infection After Allogeneic Hematopoietic Stem Cell Transplantation: Case Report and Review of the Literature

A review of endemic mycoses after hematopoietic stem cell transplantation

BACKGROUND

Endemic mycoses after hematopoietic stem cell transplantation (HSCT) are rarely reported. We aimed to comprehensively review the clinical presentation and outcomes of endemic mycoses in this immunocompromised population.

METHODS

Multiple databases were reviewed from inception through May 31, 2023 using endemic fungi as keywords (e.g., coccidioides, histoplasma, blastomyces, talaromyces, and paracoccidioides). Only hematopoietic transplants were included.

RESULTS

There were 16 publications on endemic mycoses after HSCT that reported nine unique cases of histoplasmosis, seven coccidioidomycosis, and two talaromycosis. No cases of paracoccidioides and blastomycoses were identified. Fifteen cases were allogeneic hematopoietic transplant recipients and three were autologous. Many were male (14/18, 77.8%) and overall median age was 50 (range 21-75) years. Among the 16 patients with coccidiodomycosis or histoplasmosis, fever, cytopenias and disseminated disease were the most common clinical presentations, with median onset of 8 or 12 months after HSCT, respectively. Likewise, the two HSCT patients with talaromycosis presented with disseminated disease at 12 and 48 months after transplantation. The vast majority were not on effective azole prophylaxis at the time of presentation, and many had recent intensification of immunosuppression. Nine of 18 patients died (50%), and all deaths occurred among patients with disseminated endemic mycoses.

CONCLUSION

Endemic mycoses among HSCT are uncommon. Onset was late, after discontinuation of azole prophylaxis, or was associated with intensification of immunosuppression. Disseminated disease was a common presentation, manifested by fever and cytopenias. Attributable mortality was high, and emphasizes the need for a high index of clinical suspicion so that prompt diagnosis and treatment is provided.

Acute Colonic Perforation with Septic Shock Secondary to Disseminated Histoplasmosis in an Autologous Bone Marrow Transplant Recipient

Histoplasma capsulatum is an opportunistic pathogen which can lead to a wide variety of clinical presentations in the immunocompromised host. Post-transplant histoplasmosis in hematopoietic cell transplant recipients is exceedingly rare, with an incidence of <1%. We present a case of acute caecal perforation resulting from disseminated histoplasmosis in a patient who had undergone autologous bone marrow transplant for plasma cell dyscrasia. This is a 71-year-old patient who initially presented due to progressive weakness associated with shortness of breath.

Pulmonary Histoplasmosis: A Clinical Update

Histoplasma capsulatum, the etiological agent for histoplasmosis, is a dimorphic fungus that grows as a mold in the environment and as a yeast in human tissues. The areas of highest endemicity lie within the Mississippi and Ohio River Valleys of North America and parts of Central and South America. The most common clinical presentations include pulmonary histoplasmosis, which can resemble community-acquired pneumonia, tuberculosis, sarcoidosis, or malignancy; however, certain patients can develop mediastinal involvement or progression to disseminated disease. Understanding the epidemiology, pathology, clinical presentation, and diagnostic testing performance is pivotal for a successful diagnosis. While most immunocompetent patients with mild acute or subacute pulmonary histoplasmosis should receive therapy, all immunocompromised patients and those with chronic pulmonary disease or progressive disseminated disease should also receive therapy. Liposomal amphotericin B is the agent of choice for severe or disseminated disease, and itraconazole is recommended in milder cases or as "step-down" therapy after initial improvement with amphotericin B. In this review, we discuss the current epidemiology, pathology, diagnosis, clinical presentations, and management of pulmonary histoplasmosis.

Fungal infections in hematopoietic stem-cell transplant patients: a review of epidemiology, diagnosis, and management

The advent of bone marrow transplant has opened doors to a different approach and offered a new treatment modality for various hematopoietic stem-cell-related disorders. Since the first bone marrow transplant in 1957, there has been significant progress in managing patients who undergo bone marrow transplants. Plasma-cell disorders, lymphoproliferative disorders, and myelodysplastic syndrome are the most common indications for hematopoietic stem-cell transplant. Despite the advances, invasive fungal infections remain a significant cause of morbidity and mortality in this high-risk population. The overall incidence of invasive fungal infection in patients with hematopoietic stem-cell transplant is around 4%, but the mortality in patients with allogeneic stem-cell transplant is as high as 13% in one study. Type of stem-cell transplant, conditioning regimen, and development of graft-versus-host disease are some of the risk factors that impact the risk and outcomes in patients with invasive fungal infections. Aspergillus and candida remain the two most common organisms causing invasive fungal infections. Molecular diagnostic methods have replaced some traditional methods due to their simplicity of use and rapid turnaround time. Primary prophylaxis has undoubtedly shown to improve outcomes even though breakthrough infection rates remain high. The directed treatment has seen a significant shift from amphotericin B to itraconazole, voriconazole, and echinocandins, which have shown better efficacy and fewer adverse effects. In this comprehensive review, we aim to detail epidemiology, risk factors, diagnosis, and management, including prophylaxis, empiric and directed management of invasive fungal infections in patients with hematopoietic stem-cell transplant.

Histoplasma capsulatum Infection in an Allogeneic Hematopoietic Stem Cell Transplant Patient Receiving Voriconazole Prophylaxis

Histoplasma capsulatum infection is a rare complication in the allogeneic stem cell transplant patients. Minimal guidance exists on how to appropriately manage histoplasmosis in these patients. We report a patient who developed Histoplasma pneumonia while receiving voriconazole prophylaxis at a therapeutic trough level. The patient experienced significant clinical improvement after initiation of itraconazole pharmacotherapy. We recommend a lower threshold for evaluation for histoplasmosis in allogeneic hematopoietic stem cell transplant recipients who live in endemic regions, regardless of their antifungal prophylactic regimen.

A Case of Pulmonary Histoplasmosis Presenting with Hypercalcemia and Altered Mental Status in a Patient Following Allogeneic Hematopoietic Stem Cell Transplantation

Patient: Male, 75-year-old

Final Diagnosis: Pulmonary histoplasmosis

Symptoms: Altered mental status • cough • shortness of breath

Medication: —

Clinical Procedure: —

Specialty: Pulmonology

Pulmonary infectious complications after hematopoietic stem cell transplantation: a practical guide to clinicians

PURPOSE OF REVIEW

The current review highlights the most relevant articles on lung infections following hematopoietic stem cell transplantation (HCT) published over the last year. Between 30 and 50% of HCT recipients will develop pulmonary infiltrates. These pulmonary complications may be infectious (caused by virus, bacteria, fungi, or protozoa) or noninfectious (e.g., fluid overload, heart failure, transfusion reactions like transfusion associated lung injury and transfusion-associated circulatory overload, drug reactions, engraftment syndrome, idiopathic pneumonia syndrome, diffuse alveolar hemorrhage, cryptogenic organizing pneumonia, and bronchiolitis obliterans syndrome).

RECENT FINDINGS

New data on the yield of bronchoscopy and bronchoalveolar lavage (BAL), the prevalence and clinical manifestations of respiratory viruses and the usefulness of molecular techniques for diagnosis have been published. In addition, guidelines or meta-analyses on the management of neutropenic fever, serological diagnosis of fungal infections and diagnosis and management of Pneumocystis and aspergillosis have been published.

SUMMARY

Respiratory viruses are important pathogens after HCT. PCR in the BAL is becoming the diagnostic modality of choice for a variety of infections. The best approach for the empirical management of pulmonary infiltrates following HCT remains to be defined.

Histoplasmosis in transplant recipients

Histoplasma capsulatum is a dimorphic fungus that most often causes asymptomatic infection in the immunocompetent population. In immunocompromised patients, including solid organ transplant (SOT) and hematopoietic cell transplant (HCT) recipients, however, it is likely to cause severe life-threatening infection. Post-transplant histoplasmosis (PTH) in SOT is uncommon with an incidence of ≤1% and is even rarer in HCT patients. The majority of PTH in SOT is diagnosed in the first 2 years following transplantation. Histoplasmosis may result from endogenous reactivation of latent infection, de novo post-transplant acquisition, and donor-derived infection. Disseminated infection is common. Fever is the most common symptom and clinical features are often nonspecific, but patients with disseminated infection may present with a septic picture. Other features, including pancytopenia and hepatosplenomegaly, may not be prominent early in the course of illness. Contemporary histoplasma antigen assays are the most sensitive tests but cross-reactivity with antigens of other fungi, including with Aspergillus galactomannan, is not uncommon. Treatment should be continued for at least a year. Histoplasma antigen levels have prognostic value and can be used to monitor the response to therapy. The attributable mortality is approximately 10%. Routine screening of donors and recipients is not currently recommended.