Histoplasmoma: Isolated central nervous system infection with Histoplasma capsulatum in a patient with AIDS

Brain tumour? - Cerebellar histoplasmosis as a solitary mass lesion

A 50-year-old man who had been living in Thailand presented with a history of falls, deteriorating vision and weight loss over several months. He had been admitted to a hospital in Thailand where he was given a diagnosis of multiple sclerosis. Neurological examination revealed a mild ataxic gait and lateral nystagmus, but no other abnormalities. He tested positive for human immunodeficiency virus with a CD4 cell count of 16 cells/µL. Brain magnetic resonance imaging was suggestive of an intrinsic neoplasm and he underwent stereotactic brain biopsy which showed numerous yeast-like organisms. Panfungal polymerase chain reaction was positive for Histoplasma capsulatum. He received liposomal amphotericin B for six weeks, followed by itraconazole, and started antiretroviral therapy four weeks into treatment. He developed an immune reconstitution inflammatory syndrome which responded well to steroids. Six months after diagnosis, he has no neurological symptoms or signs and remains on itraconazole. Isolated bulky central nervous system histoplasmomas are exceedingly rare. A clinical suspicion of immunosuppression was key in making this diagnosis.

What, where and why: exploring fluorodeoxyglucose-PET's ability to localise and differentiate infection from cancer

PURPOSE OF REVIEW

To review the utility of FDG-PET imaging in detecting the cause of fever and infection in patients with cancer.

RECENT FINDINGS

FDG-PET has been shown to have high sensitivity and accuracy for causes of neutropenic fever, leading to higher diagnostic certainty in this group. Recent advances in pathogen-specific labelling in PET to identify Aspergillus spp. and Yersinia spp. infections in mice, as well as differentiating between Gram-positive, Gram-negative and mycobacterial infections are promising.

SUMMARY

Patients with cancer are vulnerable to infection and fever, and the causes of these are frequently unclear using conventional diagnostic methods leading to high morbidity and mortality, length of stay and costs of care. FDG-PET/CT, with its unique complementary functional and anatomical information as well as its whole-body imaging capability, has demonstrated use in detecting occult infection in immunocompromised patients, including invasive fungal and occult bacterial infections, as well as defining extent of infection. By demonstrating disease resolution following treatment and allowing earlier cessation of therapy, FDG-PET acts as a key tool for antimicrobial and antifungal stewardship. Limitations include at times poor differentiation between infection, malignancy and sterile inflammation, however, exciting new technologies specific to infectious pathogens may help alleviate that issue. Further prospective randomised research is needed to explore these benefits in a nonbiased fashion.

Appearance of CNS histoplasmosis on 18F-FDG PET/CT with MRI correlation

Disseminated histoplasmosis is an opportunistic infection encountered in immunocompromised patients such as those with human immunodeficiency virus infection/acquired immune deficiency syndrome. Involvement of the central nervous system (CNS) can occur in 5–20% of cases of disseminated histoplasmosis, and CNS histoplasmosis can be very difficult to diagnose via conventional imaging modalities such as CT or MRI. The role of ¹⁸F-fludeoxyglucose positron emission tomography/CT scan in the diagnosis of CNS histoplasmosis has not been established. A 66-year-old female presented with dizziness and unsteady gait and was diagnosed with human immunodeficiency virus infection and CNS histoplasmosis. In this report, we present the MRI and ¹⁸F-fludeoxyglucose positron emission tomography/CT image findings.

Central Nervous System Histoplasmosis in Acquired Immunodeficiency Syndrome

BACKGROUND

Involvement of the central nervous system (CNS) by Histoplasma capsulatum in AIDS is uncommon and not easily recognized.

MATERIALS AND METHODS

CNS histoplasmosis cases from our institution were identified by a retrospective chart review from 2004-2014. A thorough literature search was performed for additional cases and their characteristics were compared. Clinical findings, treatment and outcomes are discussed.

RESULTS

A total of 5 cases from our institution were identified. They had a clinical presentation that included classic signs of meningitis, often with evidence of disseminated involvement, and was typically severe with important neurological impairment. These cases were treated with antifungal agents, including a lipid amphotericin B formulation and azole drugs, but eventually 3 experienced nonresolution of their disease likely because of lack of adherence to therapy and died from their infection. The clinical presentation, treatment and outcome of these cases did not significantly differ from cases found in the review of the literature.

CONCLUSIONS

Clinicians practicing in endemic areas should be aware of this rare but serious form of histoplasmosis. The recognition of 5 cases of CNS histoplasmosis in AIDS patients from a single institution suggests that histoplasmosis should be included in the differential diagnosis of the CNS complications of AIDS.

Histoplasmosis with Deep CNS Involvement: Case Presentation with Discussion and Literature Review

Central nervous system (CNS) histoplasmosis is rare and difficult to diagnose because it is often overlooked or mistaken for other pathologies due to its nonspecific symptoms. A 32-year-old Hispanic man with advanced acquired immunodeficiency virus presented with altered mental status and reported confusion for the past 3 months. He had a Glasgow Coma Scale of 12, repetitive nonfluent speech, and a disconjugate gaze with a right gaze preference. Lung computed tomography (CT) findings indicated a pulmonary histoplasmosis infection. Magnetic resonance imaging of the brain revealed a ring-enhancing lesion in the left caudate nucleus. A CT-guided left retroperitoneal node biopsy was performed and indicated a benign inflammatory process with organisms compatible with fungal yeast. Treatment with amphotericin B followed by itraconazole was initiated in spite of negative cerebrospinal fluid (CSF) cultures and proved effective in mitigating associated CNS lesions and resolving neurologic deficits. The patient was discharged 3 weeks later in stable condition. Six weeks later, his left basal ganglia mass decreased. Early recognition of symptoms and proper steps is key in improving outcomes of CNS histoplasmosis. Aggressive medical management is possible in the treatment of intracranial deep mass lesions, and disseminated histoplasmosis with CNS involvement can be appropriately diagnosed and treated, despite negative CSF and serology studies.

Disseminated histoplasmosis: a comparative study of the clinical features and outcome among immunocompromised and immunocompetent patients

BACKGROUND

Disseminated histoplasmosis is a chronic granulomatous disease caused by the dimorphic fungus, Histoplasma capsulatum. Clinical presentation can vary from the acute pulmonary to the chronic disseminated form. In India, disseminated histoplasmosis often presents with pyrexia of unknown origin with a presentation similar to 'disseminated tuberculosis' involving the adrenal glands and bone marrow. Due to rarity of the disease, data are lacking regarding its clinical presentation and outcome among immunocompromised and immunocompetent patients.

METHODS

During January 2000 to December 2010, we identified 37 patients of disseminated histoplasmosis and attempted to characterize the differences between immuno- compromised and immunocompetent patients. Demographic characteristics, clinical presentation, risk factors, laboratory findings, diagnostic yield, treatment received and prognosis were noted and compared between the two groups.

RESULTS

Eleven of 37 patients with disseminated histo- plasmosis were immunocompromised and 26 were immuno- competent. Comparison of their clinical features showed a higher frequency of skin lesions in the immunocompromised compared to the immunocompetent group (54.5% v. 11.5%). Pancytopenia and anaemia were more common among the immunocompromised (81.8%) compared to the immunocompetent (46.2%) group. In the immuno- compromised patients, the diagnosis was made most often by bone marrow aspirate and culture (72.7%) compared to the immunocompromised group where the diagnosis was most often obtained by adrenal gland biopsy and fungal cultures (57.7%). The cure rate was significantly higher in the immunocompetent group (73% v. 45%).

CONCLUSION

The clinical presentation and outcome of patients with disseminated histoplasmosis differs among immunocompromised and immunocompetent patients.