Podcast Summary: Derms on Drugs

Episode Title: “Psoriasiform Dermatitis and Idiopathic Erythroderma – The Derms on Drugs Clear Up Some Murky Topics”

Date: February 21, 2025
Hosts: Dr. Matt Zirwas, Dr. Laura Ferris, Dr. Tim Patton
Guest: Dr. Amber Atwater

Episode Overview

In this lively episode, the Derms on Drugs crew—Drs. Matt Zirwas, Laura Ferris, and Tim Patton—dive into two particularly challenging and often perplexing areas of clinical dermatology: psoriasiform dermatitis and idiopathic erythroderma. Special guest Dr. Amber Atwater, renowned in the field of contact dermatitis, joins the team to break down recent research, share career anecdotes, and discuss what to do when biopsies and diagnoses aren’t clear.

The episode is a playful, peer-oriented exchange with plenty of laughs, but delivers practical, up-to-date guidance for clinicians navigating these ambiguous dermatologic conditions.

Key Discussion Points

1. High-Parameter Immunophenotyping in Idiopathic Erythroderma

(01:27–09:35)

• Featured Article: Cornman et al., “Targeted dual biologic therapy for erythroderma of unknown etiology guided by high parameter peripheral blood immunophenotyping” (Nature Scientific Reports).
• Case Study: The panel discusses a remarkable case where deep blood immunophenotyping led to uncovering a unique T-cell cytokine signature (producing both IL-13 and IL-17) in a patient with unclassifiable erythroderma.
• Treatment Innovation: The patient was treated with both dupilumab and secukinumab, with dramatic improvement—an example of extreme personalized medicine.
• Clinical Pearl: Immunophenotyping may evolve into a feasible method to “target a patient’s very specific pathology,” though practicality today is limited by cost and access.

Notable Quote:

"This is personalized medicine to the max...I did a peer to peer, and this reminds me of those patients who are like, 'I want to know the root cause.' And you're like, 'You don't.'” – Dr. Laura Ferris (03:30)

• The group riffs on the realities of clinical practice, with Dr. Patton humorously suggesting,

  “You say that this guy is erythrodermic atopic because you can find some sponge on the biopsy. That gets him on the Doopie, then you give them Reflumelast… There, I just saved you $7 million.” (06:37)

• They discuss the practical first-line approach—methotrexate, cyclosporine, or dupilumab when “the diagnosis isn’t clear,” and briefly debate JAK inhibitors for broad immunosuppression (08:13–09:35).

2. Deep Dive: Psoriasiform Dermatitis Retrospective Study

(10:44–30:18)

• Featured Guest/Study: Dr. Amber Atwater discusses her retrospective cross-sectional analysis of 13 years’ worth of patients with biopsies showing “psoriasiform dermatitis” at Duke University.
• Main Findings:
  • About 1/3 eventually diagnosed with psoriasis
  • About 1/3 had dermatitis (subtypes: chronic dermatitis, allergic contact, atopic dermatitis)
  • About 1/3 had other diagnoses (e.g., lichenoid derm, CTCL, etc.)
• Anatomic Location Clues:
  • Scalp involvement ➔ Psoriasis likely
  • Face ➔ Suggests dermatitis
  • Anogenital area ➔ “Probably never going to figure out what the heck you’ve got.” (13:54)
• Publishing Realities: Dr. Atwater shares the struggle of getting the paper published after six rejections and revisions—“there’s a whole storyline there” (15:25).

Notable Quote:

“If you have it on your scalp, you probably have psoriasis. If you have it on your face, you probably have dermatitis of some sort…other than that, we don’t know.” – Dr. Matt Zirwas (13:39)

3. Patch Testing: When Is It Really Appropriate?

(17:32–23:51)

• The hosts and Dr. Atwater debate the value and overuse of patch testing.

• Dr. Atwater shares that, in her experience, referrals are usually appropriate:

  “I often think it's appropriate and sometimes it's, you know, wrongdiagnosis.com and that's appropriate too, because I can actually help the patient… The only thing the patient cares about…is clearing their skin.” (18:44)

• Dr. Ferris wonders: is benefit in patch testing, or the “thoughtful approach to the patient” that comes with being a dermatitis specialist? Dr. Atwater agrees it’s multifactorial.

• They discuss practical criteria for referring to patch testing, factoring in disease distribution (e.g., hands and eyelids= higher suspicion for allergy) and the importance of not committing patients to lifelong systemic therapy if avoidable.

4. Biopsies in “Sponge Derm” – Utility and Limitations

(25:57–28:47)

• The value of biopsies for non-resolving or generalized dermatitis is debated.
• Dr. Ferris points out that 8% of patients from Dr. Atwater’s study ended up with a diagnosis of cutaneous T-cell lymphoma (CTCL), making biopsies sometimes useful for ruling out more serious conditions.
• Dr. Atwater advises high suspicion for CTCL in generalized, chronic cases, especially in Black patients, where their data showed elevated risk.

5. The Non-Diagnosis: “Dermatitis, Unspecified”

(28:47–32:32)

• The panel ponders whether this is a real entity or “just a placeholder”—it’s the most common inflammatory dermatosis in the AAD DataDerm registry.
• Dr. Atwater suggests that chronic dermatitis and “unspecified” are often atopic dermatitis spectrum, especially post-2017 with widespread use of dupilumab and similar treatments.

Notable Quote:

"My 2017 version… would say 'unspecified dermatitis.' The now corrupt pharma version of me… I do believe in this AD spectrum disorder." – Dr. Amber Atwater (30:18)

• All panelists agree that “dermatitis unspecified” is useful clinically, even if as a billing or management placeholder.

6. Trivia Segment: Allergens of the Year

(32:32–41:39)

• Trivia theme: Allergens of the Year, with quirky historical notes and competitive banter.

  1. Lash Lure Disaster: The answer is paraphenylenediamine, not formaldehyde—the culprit behind 1930s cosmetic-related ocular reactions and subsequent FDA regulation (34:10).
  2. Bacitracin: Derived from Bacillus subtilis, isolated from a girl named Margaret Tracy (37:13).
  3. Allergen Elements: Four “elemental” allergens of the year: nickel, cobalt, chromium, and gold (39:29).

• Dr. Atwater is declared this week’s trivia winner!

Memorable Quotes

• “This is personalized medicine to the max.” – Dr. Laura Ferris (03:30)
• “You say that this guy is erythrodermic atopic because you can find some sponge on the biopsy... There, I just saved you $7 million.” – Dr. Tim Patton (06:37)
• “If you have it on your scalp, you probably have psoriasis. If you have it on your face, you probably have dermatitis... other than that, we don’t know.” – Dr. Matt Zirwas (13:39)
• “Patch testing is not the rule, it’s the exception… I’ve had acne sent to me for patch testing. I’m not going to patch test them.” – Dr. Amber Atwater (20:39)
• “My 2017 version… would say 'unspecified dermatitis.' The now corrupt pharma version of me… I do believe in this AD spectrum disorder.” – Dr. Amber Atwater (30:18)
• “That is going to conclude our deep dive for the day.” – Dr. Matt Zirwas (32:32)

Timestamps for Key Segments

• 00:19–01:27: Show introduction and guest announcement
• 01:27–06:08: Personalized immunophenotyping in erythroderma
• 06:08–09:35: Practical treatment approaches for idiopathic erythroderma; immunology banter
• 10:44–15:25: Introduction and methods/results of psoriasiform dermatitis study
• 17:32–23:51: Patch testing, when to do it, and approach to dermatitis patients
• 25:57–28:47: The role of biopsy in ambiguous dermatoses and suspicion for CTCL
• 28:47–32:32: The utility and philosophy of “dermatitis unspecified”
• 32:32–41:39: Trivia: Allergens of the Year and clinical pearls for hair dye allergies

Resources & Takeaways

• Personalized Medicine is on the Horizon: High-parameter immunophenotyping could inform dual biologic therapy but is (currently) impractical for most.
• Psoriasiform Dermatitis = Diagnostic Uncertainty: Expect “a third, a third, a third” distribution for final diagnoses (psoriasis/derm/other).
• Patch Testing: Use clinical judgment; consider especially for classic allergy distribution, but don’t overuse for non-specific eczematous rashes.
• Biopsy Utility: Key for ruling out malignancy (CTCL); otherwise, often limited for distinguishing between types of dermatitis.
• “Dermatitis unspecified” is a clinical tool, but likely represents atopic dermatitis spectrum in most cases.
• Trivia & App Recommendation: For contact dermatitis evaluations, the updated CAMP app is highly recommended.

For Listeners

If you navigate skin rashes in the trenches, this episode arms you with smart, real-world strategies, and demystifies complicated cases with evidence and expert banter. Whether deciding if a patient truly needs a patch test, wrestling with ambiguous biopsy results, or just enjoying some “derm nerd” trivia, you'll walk away with practical pearls.