Disseminated histoplasmosis in a patient with sarcoidosis: a controversial relationship and a diagnostic dilemma

Acute Disseminated Histoplasmosis with Atypical Lymphocytosis in an Immunocompetent Host

65 year-old-male presented with a one-week history of high grade fever, fatigue and confusion which began abruptly two days after a cystoscopy procedure. Past medical history included pulmonary sarcoidosis diagnosed by mediastinal lymph biopsy, diabetes and hypertension. On admission he was febrile and confused with stable vital signs. Initial workup included negative Head CT and lumbar puncture. Blood work revealed normal metabolic and liver function tests with progressive anemia, thrombocytopenia and atypical lymphocytosis of 15–20%. Blood, urine and respiratory cultures all were negative for bacteria and. A bone marrow biopsy was done given the abnormal lymphocytes in peripheral smear, revealing budding yeast consistent with Histoplasma capsulatum. Histoplasma antigen was positive in urine and eventually blood and bone marrow grew H. capsulatum. Patient was started on amphotericin-B for diagnosis of disseminated histoplasmosis. After a 2 week period of amphotericin B, patient was switched to oral Itraconazole to complete 12 months course of treatment.

The intricate relationship of histoplasmosis and sarcoidosis: a case report

Introduction

Histoplasmosis is an endemic mycosis with most cases of clinical illness reported in North and Central America. Rarely, patients develop progressive disseminated histoplasmosis with extrapulmonary manifestations. These infections are fatal if not appropriately treated.

Case presentation

We report a case of progressive disseminated histoplasmosis presenting with fever, progressive dyspnea, and pancytopenia in a 51-year-old Caucasian man who had been treated with chronic steroids for a diagnosis of sarcoidosis made 20 years previously. His presentation was initially mistaken for sarcoidosis but, fortunately, laboratory results showed hematologic abnormalities, and the diagnosis of histoplasmosis was made by bone marrow biopsy.

Conclusions

Sarcoidosis reduces T cell activity, and the addition of steroids for treatment causes further immunosuppression and vulnerability for development of a disseminated infection. The diagnosis of histoplasmosis depends mainly on clinical presentation and host factors. Although there are diagnostic laboratory tests available, clinicians may need to diagnose histoplasmosis by history and physical examination alone and treat empirically, since awaiting Histoplasma-specific laboratory results would delay initiation of treatment. Primary care providers, hospitalists, and subspecialists alike should be aware of the overlap in clinical and radiological presentations of sarcoidosis and histoplasmosis, and when and how to pursue diagnostic testing for endemic mycoses, since these infections can be fatal in immunosuppressed patients without appropriate treatment.

Histoplasmosis: a clinical and laboratory update

Infection with Histoplasma capsulatum occurs commonly in areas in the Midwestern United States and Central America, but symptomatic disease requiring medical care is manifest in very few patients. The extent of disease depends on the number of conidia inhaled and the function of the host's cellular immune system. Pulmonary infection is the primary manifestation of histoplasmosis, varying from mild pneumonitis to severe acute respiratory distress syndrome. In those with emphysema, a chronic progressive form of histoplasmosis can ensue. Dissemination of H. capsulatum within macrophages is common and becomes symptomatic primarily in patients with defects in cellular immunity. The spectrum of disseminated infection includes acute, severe, life-threatening sepsis and chronic, slowly progressive infection. Diagnostic accuracy has improved greatly with the use of an assay for Histoplasma antigen in the urine; serology remains useful for certain forms of histoplasmosis, and culture is the ultimate confirming diagnostic test. Classically, histoplasmosis has been treated with long courses of amphotericin B. Today, amphotericin B is rarely used except for severe infection and then only for a few weeks, followed by azole therapy. Itraconazole is the azole of choice following initial amphotericin B treatment and for primary treatment of mild to moderate histoplasmosis.

Fungal infections as a complication of therapy for sarcoidosis

BACKGROUND

Treatment of symptomatic sarcoidosis usually includes systemic immunosuppressive agents. These agents may render the patient more susceptible to opportunistic infections. In addition, the fungal infection may be difficult to distinguish from the underlying sarcoidosis.

AIM

To examine the presentation and management of invasive fungal infections in sarcoidosis patients.

DESIGN

Retrospective record review.

METHODS

We reviewed the notes of all sarcoidosis patients (n = 753) seen at our clinic over an 18-month period.

RESULTS

Seven patients (0.9%) with previously diagnosed sarcoidosis developed fungal infections: two each with Histoplasma capsulatum and Blastomyces dermatitidis and three others with Cryptococcus neoformans. No cases of invasive aspergillus or tuberculosis were identified. The diagnosis of fungal infection was made by bronchoscopy (four cases), open-lung biopsy (one case), bone-marrow aspirate (one case), and spinal fluid examination (one case). All patients were receiving corticosteroids at the time of worsening chest X-ray or clinical status. Four patients were also receiving methotrexate prior to infection. No patient with systemic fungal infection was receiving either infliximab or cyclophosphamide. All patients responded to anti-fungal therapy and a reduction in immunosuppression.

DISCUSSION

Fungal infections occur rarely in treated patients with sarcoidosis. Deterioration of chest X-ray, especially a localized infiltrate, warrants investigation.

Histoplasmosis

The diagnosis of histoplasmosis depends on recognition of the different clinical manifestations of infection, accompanied by knowledge of the accuracy and limitations of tests used for diagnosis of fungal infections. Although most infections are asymptomatic, histoplasmosis can be severe, or even fatal, in patients who have experienced a heavy exposure, have underlying immune defects, or develop progressive disease that is not recognized and treated. This article provides an up-to-date clinical review of histoplasmosis, focusing on recognition, diagnosis, and management.