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Patient Case: Disseminated Histoplasmosis

Patient Case: Disseminated Histoplasmosis

Discussion

Chief Complaint: “I’ve had a persistent fever, weight loss, and a cough for the past month.”

History of Present Illness:
A 51-year-old man presents with fever, night sweats, chronic cough, and unintentional weight loss of 7 kg (15 lbs) over the past month. He also complains of fatigue and occasional shortness of breath. He works in construction and recently renovated an old building, which had bird and bat droppings in the attic.

He has a history of HIV, but he has been off antiretroviral therapy (ART) for the past year. He denies recent travel outside the country, sick contacts, or tuberculosis exposure.

Past Medical History:

  • HIV (last CD4 count unknown)
  • No known drug allergies

Physical Examination:

  • Vitals: Fever (38.5°C), tachycardia, mild tachypnea
  • Skin: A few erythematous papules with central ulceration
  • Lungs: Bilateral crackles at lung bases
  • Abdomen: Mild hepatosplenomegaly
  • Neurologic: No focal deficits

Diagnosis:
The combination of fever, weight loss, chronic cough, skin lesions, and hepatosplenomegaly in an immunocompromised patient with recent exposure to bat droppings suggests disseminated histoplasmosis, caused by Histoplasma capsulatum.

Diagnostic Tests:

  • Chest X-ray: Diffuse interstitial infiltrates
  • Serum and urine Histoplasma antigen tests: Positive
  • Fungal blood cultures: Pending
  • Skin biopsy of lesion: Shows yeast-filled macrophages on PAS stain

Management Plan:

  • Induction therapy: IV liposomal amphotericin B for 2 weeks
  • Consolidation therapy: Oral itraconazole for at least 12 months
  • Restart ART after antifungal treatment is established
  • Monitor for immune reconstitution inflammatory syndrome (IRIS)

The patient is counseled on the importance of ART adherence and avoiding environments with bird or bat droppings, which can harbor Histoplasma capsulatum.

Questions
  1. What is the most likely diagnosis in this patient?
    a) Tuberculosis
    b) Disseminated histoplasmosis
    c) Pneumocystis pneumonia (PCP)
    d) Cryptococcal meningitis
  2. Which exposure history increases the risk of histoplasmosis?
    a) Swimming in freshwater lakes
    b) Handling pet reptiles
    c) Exposure to bird and bat droppings
    d) Eating undercooked meat
  3. What is the most appropriate initial treatment for disseminated histoplasmosis in this patient?
    a) Oral fluconazole
    b) IV amphotericin B
    c) Trimethoprim-sulfamethoxazole
    d) IV ceftriaxone
  4. Why should ART initiation be delayed in this patient?
    a) To prevent immune reconstitution inflammatory syndrome (IRIS)
    b) To allow full clearance of Histoplasma before restarting ART
    c) Because antifungal therapy interferes with ART
    d) Because ART is ineffective in fungal infections
Reveal answers

Answers

  1. (b) Disseminated histoplasmosis – The patient's fever, weight loss, respiratory symptoms, skin lesions, and hepatosplenomegaly in the context of HIV and bat/bird exposure strongly suggests disseminated histoplasmosis, a common opportunistic infection in immunocompromised individuals.
  2. (c) Exposure to bird and bat droppings – Histoplasma capsulatum thrives in soil contaminated with bird and bat droppings, often found in caves, old buildings, and chicken coops. Inhalation of fungal spores can lead to infection.
  3. (b) IV amphotericin B – Severe disseminated histoplasmosis requires IV liposomal amphotericin B for at least two weeks, followed by oral itraconazole for maintenance therapy.
  4. (a) To prevent immune reconstitution inflammatory syndrome (IRIS) – Delaying ART initiation helps avoid IRIS, a severe inflammatory response that can worsen symptoms if the immune system rapidly recovers while fungal infection is still present. ART is usually restarted 2–4 weeks after antifungal therapy begins.

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