Harrison Nguyen, MD, MBA, MPH, is a double board-certified dermatologist/Mohs micrographic surgeon and clinical researcher in Houston, Texas.

Harrison Nguyen, MD, MBA, MPH

A session was presented by Harrison Nguyen, MD, MPA, MPH, at the 

Society of Dermatology Physician Associates (SDPA) 2025 Fall Conference

 in San Antonio, titled ‘Patterns in Red and Purple: Decoding Vasculitis in the Skin.’

, Nguyen, a clinical assistant professor of dermatology at Baylor College of Medicine, spoke on the pathways driving chronic spontaneous urticaria (CSU).

 In this interview, Nhuyen highlighted his session on vasculitis, responding to questions about the hallmarks of this cutaneous condition.

What Are the Hallmarks of Cutaneous Vasculitis? With Harrison Nguyen, MD, MBA, MPH

"Vasculitis is often presents on the skin, and what's important to understand is that vasculitis is often a reaction, as opposed to a primary disease,” Nguyen explained. “So, the job as dermatologists and dermatology clinicians is to be able to recognize that it's vasculitis and then to put our detective hats on to see if there's any important drivers of this reactive pattern. The majority of the time…we can treat symptomatically, but in the situations where there are other conditions that may be driving vasculitis, it's important for us to identify those.

Nguyen went on to describe other elements in his talk. Dermatologists, Nguyen noted, are often the individuals to whom vasculitis first presents, and patients can be afraid of this condition.

“It can present differently based on the type of vasculitis,” Nguyen expressed. “We often classify it based on the vessel size. So small vessel vasculitis, medium vessel vasculitis, and large vessel vasculitis, present differently. Small vessel vasculitis often presents with papules and often in the lower extremities, as it gets larger vessels, and then we start to see things like retiform purpura ulcers. But it's important for us to do the right workup to make this diagnosis. A biopsy is important.”

Nguyen continued his discussion of the session on cutaneous vasculitis, highlighting the approach to a biopsy for this condition.

“Biopsies are being done, but I hope that we can emphasize that it's important to also do a “DIF’ or a direct immunofluorescence biopsy,” Nguyen said. “Also, the selection of the lesion can be helpful. We don't want too fresh of a lesion, and we don't want it too old of a lesion either, because that can actually distort the interpretation. So really, a lesion that's 24 to 48 hours in age is the right time, right lesion to biopsy.”

For any additional information on this topic, view the full video posted above. To find out more about the conference, view the latest coverage.

The quotes implemented in this interview summary were edited for clarity.

Nguyen had no relevant financial disclosures of note.

Nguyen H. Patterns in Red and Purple: Decoding Vasculitis in the Skin. Presented at the Society of Dermatology Physician Associates (SDPA) Fall Conference, November 5-9, San Antonio, TX.

Nguyen H. Immune Pathways Driving Chronic Spontaneous Urticaria, With Harrison Nguyen, MD, MBA, MPH. HCPLive. November 10, 2025. 

https://www.hcplive.com/view/immune-pathways-chronic-spontaneous-urticaria-harrison-nguyen-md-mba-mph

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In this segment of his SDPA Fall interview, Nguyen highlighted his second talk ‘Patterns in Red and Purple: Decoding Vasculitis in the Skin.’

Harrison Nguyen, MD, MPA, MPH, gave an interview with 

 in San Antonio regarding his conference talk on 

Nguyen serves as a clinical assistant professor of dermatology at Baylor College of Medicine. His session, titled ‘The Itch Within: Immune Pathways Driving Chronic Spontaneous Urticaria,’ featured a discussion of the evolving understanding of the immunologic mechanisms in CSU, including the roles of mast cell disregulation, autoimmunity, and type 2b inflammation.

Immune Pathways Driving Chronic Spontaneous Urticaria, With Harrison Nguyen, MD, MBA, MPH

“CSU can be a tremendously impactful condition, with wheels lasting 6 weeks or longer,” Nguyen said. “What we know is more heterogeneous than I think we had originally anticipated. And this is why some patients don't respond to high-dose antihistamines, why they don't respond to treatment with omalizumab. What we did was we took a dive into the mast cell.”

Nguyen highlighted emerging basic science discoveries and their relationship with practical clinical insights in the CSU space. He was asked how such immune pathways inform diagnostic approaches and decision-making related to therapeutics.

“What we did was we took a dive into the mast cell,” Nguyen said. “I compared the mast cell to Dwight Schrute from The Office. For 

 fans out there, it's Dwight Schrute who is wreaking havoc on the body. So with Dwight Schrute and the mast cell, he can be activated by two different pathways, a type one and a type 2b. Type one is dependent on IgE, which leads to activation of the mast cell, and type 2b is more dependent on IgG. 50% of patients will have an overlap of the two.”

Nguyen touched on several key elements of the mast cell with this analogy, highlighting different pathways, such as the BTK pathway, leading to degranulation in the mast cell.

“But then we also looked at type 2 inflammation, which I compared to Michael Scott in 

,” Nguyen explained. “He's the one who is creating the environment that leads to Dwight Schrute wreaking havoc. So if we can block type 2 inflammation, especially blockade of IL-4 and IL-13, it can improve patient symptoms with CSU.”

Nguyen sought to allow for a greater appreciation of the immunopathogenesis of CSU as well as its implications for current and future strategies for management of the disease.

For more information on CSU, view the full video posted above. To find out more from the conference, view our 

The quotes used in this interview were edited for clarity.

Nguyen had no relevant financial disclosures of note

Nguyen H. The Itch Within: Immune Pathways Driving Chronic Spontaneous Urticaria. Presented at the Society of Dermatology Physician Associates (SDPA) Fall Conference, November 5-9, San Antonio, TX.

This interview features Nguyen discussing his SDPA talk titled ‘The Itch Within: Immune Pathways Driving Chronic Spontaneous Urticaria.’

Harrison Nguyen, MD, MBA, MPH

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