Histoplasmosis of the central nervous system

Infectious Myelopathies

PURPOSE OF REVIEW

This article reviews infectious etiologies of spinal cord dysfunction, emphasizing the importance of recognizing common clinicoradiographic syndromes and interpreting them in the context of exposure risk and individual host susceptibilities.

RECENT FINDINGS

This article discusses the shifting spectrum of neurologic infectious diseases, the growing population of patients who are immunocompromised, and the emergence of effective antiretroviral therapies. In addition, it discusses new molecular and serologic tests that have the potential to enhance our ability to rapidly and accurately diagnose infectious diseases of the spine.

SUMMARY

When evaluating patients with suspected infectious myelopathies, it is imperative to narrow the range of pathogens under consideration. The geography, seasonality, and clinicoradiographic presentation and immunocompetence status of the patient define the range of potential pathogens and should guide testing and initial management.

Primary Central Nervous System Infection by Histoplasma in an Immunocompetent Adult

Central nervous system (CNS) infection by Histoplasma capsulatum is a rare disease in immunocompromised individuals in endemic areas. About one quarter of cases result from hematogenous dissemination. A 23-year-old upholsterer with chronic occipital headache had developed intracranial hypertension and dizziness, incoordination with ataxic gait, and acute confusion 5 months prior to admission. Laboratory examinations and chest roentgenogram were normal. Postcontrast T1-weighted MRI of the brain revealed a multiple ring-enhancing cerebellar, brain stem and parietal lobe lesions, and meningeal contrast enhancement. Cerebrospinal fluid culture was positive for H. capsulatum species complex, which was confirmed by phylogenetic analysis. Thirteen years after the diagnosis and treatment, there was no H. capsulatum recurrence; sequels related to complications due to the ventriculoperitoneal shunt. This case shows a primary neurological presentation of cerebral histoplasmosis, without meningitis or disseminated disease in nonimmune-compromised patient. The authors propose a categorization of the diagnosis of CNS histoplasmosis. Routine diagnostics of sibling species within the H. capsulatum complex proved to be difficult.

Cognitive impairment and memory loss associated with histoplasmosis: a case study

Histoplasmosis is a rare disease caused by inhalation of the fungus Histoplasma capsulatum. It can spread via cerebral circulation to the central nervous system as a manifestation of a disseminated infection; particularly in patients with immune suppression, which can result in isolated ring-enhancing lesions and inflammation in the brain. Of the reported disseminated histoplasmosis cases (approximately 1 in 2000 per year), only 5-20% have evidence of central nervous system involvement. This paper reviews a single case study of a 57-year-old female diagnosed with disseminated CNS histoplasmosis. Patient's complaints included reduced short-term memory, word-finding problems, and difficulty organizing, making decisions, getting lost while driving, recalling names, retaining information while reading, and slowed processing speed. There was also a history of mild depression and anxiety. Direct testing revealed deficits in multiple cognitive domains including complex attention, processing speed, semantic fluency, visual scanning, motor speed, set-shifting, naming, nonverbal memory, and verbal memory. Neuropsychological deficits suggest cortical and subcortical brain dysfunction, including anterior, temporal, and mesial-temporal regions. This case illustrates the need for neuropsychologists to understand histoplasmosis, the related pathophysiology, and the neuropsychological impact; particularly with the potential for delayed progression.

Fungal infection of a ventriculoperitoneal shunt: histoplasmosis diagnosis and treatment

BACKGROUND

Histoplasmosis is a fungal disease caused by Histoplasma capsulatum, commonly found in the Americas, and Histoplasma duboisii, located in Africa. In the United States, H. capsulatum is prevalent in the Ohio and Mississippi river valleys. In rare circumstances, central nervous system (CNS) histoplasmosis infection can be caused by shunt placement. We present a case report of a 45-year-old woman in whom CNS histoplasmosis developed after having a ventriculoperitoneal (VP) shunt placed for communicating hydrocephalus. A review of the literature on fungal infections after CNS shunt placement as well as treatment options for this subset of patients was undertaken.

METHODS

The PubMed database current to 1958 was filtered and limited to English-language articles. Fifty-eight articles were selected for review based on evidence of information regarding the fungal organism responsible for shunt infection, symptoms, treatment, and/or outcomes. Also included in this review is our case study.

RESULTS

A thorough analysis of the PubMed database revealed 58 reported cases of CNS shunt-related fungal infections in the English-language medical literature as well as 7 therapeutic agents used to treat patients in whom postshunt fungal infections developed.

CONCLUSIONS

We describe the steps in diagnosis of histoplasmosis after shunt placement, provide an effective therapeutic regimen, and review the present understanding of CNS fungal infections. The medical literature was surveyed to compare and analyze various CNS fungal infections that can arise from shunt placement as well as treatments rendered.

Pathology of tropical diseases

Tropical diseases affecting the central nervous system include infections, infestations, and nutritional deficiency disorders. This article discusses the commonly encountered diseases. The infections include bacterial, mycobacterial, fungal, parasitic, and viral infections with varied clinical manifestations. Imaging sensitivity and specificity for the prediction of the cause of infections has improved with application of advanced techniques. Microbial demonstration and histology remain the gold standard for diagnosis. Understanding the basis of imaging changes is mandatory for better evaluation of images. Nutritional disorders present with generalized and nonspecific imaging manifestations. The pathology of commonly encountered vitamin deficiencies is also discussed.

Histoplasma-associated inflammatory pseudotumour of the kidney mimicking renal carcinoma

A 56-year-old female, originally from Suriname, with an otherwise unremarkable previous medical history was found to have a renal mass highly suspicious for renal cancer for which a nephrectomy was performed. Within the kidney, a tumourous mass was found which, on histological examination, showed an inflammatory pseudotumour caused by Histoplasma capsulatum. Further investigations revealed an idiopathic CD4(+) lymphopenia. Mass lesions mimicking a malignant tumour caused by infection with Histoplasma have rarely been described. To the best of our knowledge, this is the first report of a Histoplasma-associated inflammatory pseudotumour mimicking cancer occurring in the kidney.

Histoplasma capsulatum yeast phase-specific protein Yps3p induces Toll-like receptor 2 signaling

Histoplasma capsulatum is a common cause of fungal infection in certain geographic areas, and although most infections are asymptomatic, it is capable of causing histoplasmosis, a disseminated, life-threatening disease, especially in immunocompromised individuals. A deeper understanding of this host-pathogen interaction is needed to develop novel therapeutic strategies to counter lethal infection. Although several lines of evidence suggest that this fungus is neurotropic in HIV patients, little is known about the immunobiology of Histoplasma infection in the central nervous system [CNS]. The goal of the present study was to understand the innate neuroimmune mechanisms that recognize H. capsulatum during the initial stages of infection. Using a 293T stable cell line expressing murine Toll-like receptor 2 [TLR2], we show here that TLR2 recognizes H. capsulatum cell wall protein Yps3p and induces the activation of NF-κB. In further experiments, we tested the ability of Yps3p to induce signaling from TLR2 in primary microglial cells, the resident brain macrophages of the CNS. Our data show that H. capsulatum Yps3p induced TLR2 signaling in wild-type microglia, but not in microglia isolated from TLR2 KO mice, confirming that Yps3p is a ligand for TLR2. Furthermore, Yps3p-induced TLR2 signaling was suppressed by vaccinia virus-encoded TLR inhibitors. This is the first demonstration of a fungal protein serving as a TLR ligand and mediating signaling in primary brain cells.

[Disseminated and central nervous system Histoplasma capsulatum infection mimicking neoplasm: difficulties in diagnosis, failure in management]

INTRODUCTION

Infection with Histoplasma capsulatum (Hc) is a rare importing disease in metropolitan France, the most often minor but sometimes letal in its spread form.

EXEGESIS

A 58 years old French man, HIV seronegative, was admitted for an alteration of its general condition, disorder and buccal ulcerations. He had a prostate cancer history and came back in France after 17 years in Central Africa. The imaging showed numerous cerebral nodes, a bilateral adrenal tumor, and pulmonary calcifications. Histoplasmosis diagnosis has been done after neurosurgical cerebral biopsy which displayed characteristic Hc. The sick man died 4 months later with multivisceral failures, in spite of amphotericine B treatment followed by oral then intraveinous itraconazole.

CONCLUSION

Even in an old tropical residence, ones can be able to conjure up a deep exotic fungal infection, and most specifically Hc histoplasmosis, in front of meaningful multivisceral lesions. Disseminated histoplasmosis (HD) with neurological location is misleading, mimicking tuberculosis or cancer. In order to obtain formal mycological evidence, ones have to make adapted biopsies. Antifungal agents must take into account medicinal interaction. Therefore, prognosis is bad, according to inoculum, immunodeficiency, age of disease and diagnosis delay.

Intramedullary histoplasmosis spinal cord abscess in a nonendemic region: case report and review of the literature

An immunocompetent patient from a nonendemic region developed a rare intramedullary thoracic histoplasmoma. A native Arizonan, with no history of travel to endemic regions, received 3 months of itraconazole for confirmed gastrointestinal histoplasmosis at an outside institution. Two years later she experienced the rapid onset of paraplegia and lost bowel and bladder function. Magnetic resonance imaging demonstrated a ring-enhancing intramedullary lesion at T2 and signal abnormality from C2 to T5. Emergent T2-T3 laminectomy was performed with ultrasonographically guided intradural exploration and midline myelotomy. The intramedullary abscess was drained. She was nonambulatory, but motor function was partially restored. An Ommaya reservoir was later placed to deliver amphotericin and a new antifungal agent, voriconazole. Magnetic resonance imaging confirmed that the infection had resolved. Intramedullary spinal histoplasmoma is a rare manifestation of disseminated histoplasmosis, particularly in nonendemic regions. Surgery for focal mass lesions and aggressive antifungal chemotherapy are the optimal treatment. Newer central nervous system-penetrating antibiotics show promise in refractory cases.

Epididymal histoplasmosis diagnosed by isolation of Histoplasma capsulatum from semen

An autochthonous case of epididymal histoplasmosis masquerading as tuberculosis in a 55-year-old male patient is reported from India. It was diagnosed by culture of Histoplasma capsulatum from semen and by demonstration of the fungus upon re-examination of epididymal biopsy sections previously misinterpreted as tuberculous granuloma. The patient's main complaints were painful epididymal swelling, occasional fever and cough. He was treated successfully by excision of epididymis and vas deferens combined with amphotericin B therapy. This is believed to be the first case of epididymal histoplasmosis to be reported outside the American continent and the fourth of its type reported in the English literature. The case is also noteworthy in that H. capsulatum was isolated for the first time from semen, and it underlines the importance of mycological culture of semen specimens for diagnosis of genitourinary infections of obscure etiology.

Successful medical treatment of a spinal histoplasmoma

A woman with previously treated disseminated histoplasmosis was admitted with progressive paraparesis. Magnetic resonance imaging showed multifocal cerebritis and spinal histoplasmoma. She recovered following a second treatment with amphotericin B. This is the fourth reported patient with intramedullary spinal histoplasmoma, and the first demonstrating successful treatment of the lesion with medical therapy alone.