How to Recognize Systemic Mastocytosis in a Patient, With Hussein Abbas, MD, PhD

Early recognition of a rash as something more has the potential to change lives if a clinician identifies systemic macrocytosis.

Systemic macrocytosis, a rare but impactful disease often first observed in the skin, was covered in a recent session at the 2025 Society of Dermatology Physician Associates (SDPA) Fall Conference, titled ‘When a Rash Is More than Skin Deep: Systemic Mastocytosis Essentials.’1 In an interview with HCPLive, the presenter and assistant professor at the University of Texas MD Anderson Cancer Center in Houston spoke about this talk.

“I think one of the main challenges that physicians face, and also patients face, is when they have a rare disease that they can't really diagnose,” Abbas explained. “Systemic mastocytosis is a very rare disease, but it's also a significant disease because it can really create a lot of symptom burden to patients, and also in some cases, can impact the longevity and how long people live and the quality of life that they have.”

In his session, Abbas sought to help attendees to explore some of the diagnostic pathways, key clinical clues, and strategies for collaborative management with hematology/oncology specialists.

“One of the main takeaways is that systemic mesocytosis is under-recognized, and working together is important [so that we] recognize it,” Abbas said. “Why is that? Because the first people who see the disease, most commonly are sometimes dermatologists or allergists, because patients can present with skin rashes in common cases, though not always. Or they could also present with allergies to things or reactions to things, recognizing, however, that this is systemic mastocytosis, which requires a workup, and that workup includes enzymes like tryptase from the blood.”

Abbas went on in his description of the session, noting most patients who have cutaneous mastocytosis also have disease elsewhere. He noted the cutaneous manifestations could be grouped into 3 main groups, 1 of which is referred to as maculopapular cutaneous mastocytosis (MPCM).

“This is when you have brown, reddish lesions,” Abbas said. “They could be the same shape around the skin, all over, and usually, if they're an adult, we can see them. You can recognize them by the brownish color and…when you try to palpate it or kind of stimulate that lesion, it can cause a reaction on the skin.”

For more tips on identifying systemic macrocytosis, view the full video posted above.

The quotes contained in this interview were edited for clarity.

Abbas did not have relevant financial disclosures of note.

References

1. Abbas H. When a Rash Is More than Skin Deep: Systemic Mastocytosis Essentials. Presented at the Society of Dermatology Physician Associates (SDPA) Fall Conference, November 5-9, San Antonio, TX.