Run the List – Episode Summary

Podcast: Run the List
Episode: Blastomycosis
Date: August 11, 2025
Host: Walker Redd
Guest: Dr. Matthew Pullin (Assistant Professor, Infectious Diseases, University of Minnesota)

Overview

This episode targets medical trainees and practitioners, shedding light on the often-overlooked endemic fungal infection: blastomycosis. Walker Redd welcomes Dr. Matthew Pullin, an infectious disease specialist, to guide listeners through the clinical presentation, diagnosis, and management of blastomycosis, using a rich case study to highlight diagnostic challenges, current epidemiology, and practical clinical pearls.

Case Presentation (03:00)

Patient: 45-year-old man

• History: Metabolic-associated liver disease, hypertension
• Symptoms:
  • Large, purple-black enlarging lesions on trunk, flank, thighs (non-tender, non-pruritic)
  • Sharp ankle pain
  • Mild, self-resolving respiratory illness two months prior after clearing rotting wood in rural Pennsylvania
  • No current respiratory complaints; stable vitals; well-appearing
• Exam: Lesions per history; grimace with ankle weight bearing; lungs clear

Initial Reaction:
Walker: “Honestly if I was seeing this patient, one of my first thoughts would be that I probably need to get the help of an infectious disease doctor.” (04:13)

Key Discussion Points & Insights

Recognizing Blastomycosis (04:29)

• Classic Presentation:
  Dr. Pullin: “This is a pretty classic presentation for disseminated blastomycosis. The tricky part...is that it can have a really varied presentation. About half of those infected...will remain asymptomatic and self resolve. But the most common symptomatic presentation is the classic respiratory syndrome, typically called the pneumonia, that doesn't improve with antibiotics.” (04:30)

• Sites of Dissemination: Skin, bones, genitourinary tract, and CNS

Importance of Exposure History (05:21)

• Geography & Environment:
  Blastomyces found in soil/rotting wood, especially in the Ohio River Valley
• Reservoirs:
  “Classically, we used to call this the hunter's disease, because hunting dogs would get blastomycosis. Even today, we see this pattern of someone coming in with respiratory symptoms...and then they say, hey, you know, my dog had similar symptoms...Dogs...disturb those spores and kick them up into the air, which leads to their human being infected as well.” (05:48)

Epidemiological Shifts (06:55)

• Expanding Endemic Range:
  “More recent studies...have shown that the geographic range...are expanding. Part of that is just revealing what was probably there the whole time...also the climate’s changing—it’s getting warmer and more humid everywhere, which is what these fungi love.” (07:05)

Clinical Presentations (08:00)

Pulmonary Disease

• Ranges from mild subacute pneumonia to ARDS
• Mortality with ARDS: nearly 50%
• Mimics: Bacterial pneumonia, TB, malignancy
• “Imaging findings...are pretty widely variable and often not very helpful…patchy opacities to cavitary lesions to the super unhelpful tree and bud appearance…” (08:34)

Extrapulmonary Disease (09:25)

• Disseminated Disease: Occurs in 25–40% of cases
  • Skin: 40–80% of disseminated cases—papulopustular, verrucous plaques, ulcerated nodules, abscesses
  • Bones: 5–25%—osteomyelitis, abscess/sinus tracts, septic arthritis
  • GU tract: <10%
  • CNS: 5–10%—meningitis, mass lesions; more common in immunocompromised

Diagnostic Approach (11:15)

Core Principle

“The old adage of tissue is the issue applies. If you can biopsy something, biopsy it…that can lead you to a quick diagnosis just by a preliminary pathology exam that shows budding yeast.” (11:19)

Modalities

• Biopsy: Of skin/bone lesions—broad-based budding yeast on stains (e.g., GMS)
• Antigen Testing: Blood, urine, CSF, BAL
  • Caveat: Cross-reactivity with other endemic fungi (Histoplasma, Talaromyces, Paracoccidioides)
• Cultures: May take up to 5 weeks
• Emerging Diagnostics: PCR/next generation sequencing (not routine yet)

Treatment Principles (13:14)

• Severity Determines Regimen: “The main break point is amphotericin or no amphotericin.” (13:15)
• Mild–Moderate Pulmonary or Disseminated (no CNS):
  • Oral azole (most often itraconazole) for 6–12 months
• Severe Disease, CNS involvement, or Immunocompromised:
  • Liposomal amphotericin B induction (1–2 weeks+)
  • Step down to itraconazole (oral)
  • Life-long suppression for certain immunocompromised patients
• Itraconazole Caveats:
  • Drug-drug interactions, GI side effects, variable absorption
  • If intolerant: posaconazole or voriconazole (less data)
  • Always get ID involved for complicated cases

Top Three Clinical Pearls (15:39)

1. Blastomycosis Mimics Many Other Diseases:
   “So your workup just isn't quite making sense with your working diagnosis and they have a compatible exposure history—think blastomycosis.”
2. Diagnostics:
   “Consider tissue in your diagnostics combined with antigen testing.”
3. Treatment:
   “Itraconazole is the most well studied oral therapy and should be preceded by induction therapy with liposomal amphotericin in severe cases, CNS disease or any infection in an immunocompromised patient.”

Notable Quotes & Memorable Moments

• Memorability of the “Hunter’s Disease”:
  “...my dog had similar symptoms a couple weeks before me.” (06:09)
• Classic idiom:
  “Tissue is the issue.” (11:16)
• Host enthusiasm:
  “This case presentation...is one of the more interesting case presentations we've ever done on Run the List and I'm so excited for you to be here today, Matt.” (02:39)
• Pearl delivery:
  “Love it.” (15:08)—Dr. Pullin, regarding calling ID for complicated management

Additional Resource (16:10)

Dr. Pullin’s Research:

“If you have any patients with blastomycosis or histoplasmosis or coccidioidomycosis, please send them our way. The website is fungalstudy.org—we're doing a large nationwide online study looking at patient reported outcomes and treatment responses. All they have to do is answer online surveys and we'd love to hear from people out there...” (16:24)

Important Timestamps

• Exposure and Initial Presentation: 03:00–05:08
• Epidemiology Shift: 06:55–07:47
• Pulmonary and Extrapulmonary Manifestations: 08:00–10:50
• Diagnostic Approach: 11:15–12:57
• Treatment Overview: 13:14–15:18
• Key Clinical Pearls: 15:39–16:41

Tone & Language

• Conversational, practical, and high-yield.
• Jargon appropriate for trainees but accessible.
• Frequent repeated emphasis on real-world diagnostic challenges and actionable steps.

A compact but comprehensive look at blastomycosis, this episode is an exemplar for trainees wanting to deepen their clinical reasoning for rare yet regionally significant infections.