What Does Cutaneous Mastocytosis Look Like?

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Patient Presentation
While sitting in clinic, a pediatrician noticed that all the medical students and residents were filing into a patient room, and then filed out a few minutes later. She asked her colleague what was so interesting with the patient. “Oh, a 6-month-old male has a solitary mastocytoma and none of the learners had seen one. The Darier sign was really good for them to see and the baby was fine. The mom was happy to know what it was,” she replied.

Discussion
Mastocytosis is group of diseases where there is pathological accumulation of mast cells in different tissues. Cutaneous involvement is one of the most common, but other tissues can include bone marrow, gastrointestinal tract, lymph nodes, liver, or spleen. Systemic mastocytosis usually also has some cutaneous involvement.

Cutaneous involvement has three subtypes:

  • Solitary (1-3 lesions) – 10-15%
  • Maculopapular cutaneous mastocytosis also called urticaria pigmentosa – most frequent form, 70-80% of children
  • Diffuse cutaneous mastocytosis – 5-13%

Mastocytosis overall has a prevalence of 9 per 100,000 persons. In the pediatric age group about 80% have cutaneous mastocytosis. Most patients present in infancy especially the first year, especially the first 6 months. Mastocytosis is associated with the c-KIT gene which regulates stem cell division and activation mutations which result in abnormal proliferation of melanocytes and mast cells.

Diagnosis is clinical but serum tryptase can be elevated in systemic mastocytosis and can assist in diagnosis. Serum tryptase is normal in cutaneous mastocytosis. Biopsy usually is not needed but can be helpful if the diagnosis is in doubt. Most patients are treated symptomatically with avoidance of triggers (see below) and antihistamines as mainstays. Long term most patients (80%) have resolution or minimization of their lesions and symptoms by puberty.

Learning Point
The presentation of the cutaneous lesions can be variable but often are:

  • Round or oval shape
  • 1-5 cm in diameter
  • Red-brown, yellow brown in color
  • Indurated and/or erythematous
  • Leathery or peau d’orange appearance and/or consistency
  • Margins are sharp or indistinct

An image search of cutaneous mastocytosis can be found here.

When rubbed or irritated they can degranulate and release histamine and other vasoactive mediators producing an urticarial reaction with erythema, edema and elevation and/or pruritis of the lesion and surrounding area. This reaction is termed Darier sign. Darier sign is often considered pathognomic but it can also be seen sometimes in juvenile xanthogranuloma or cutaneous lesions of acute lymphocytic leukemia. An absent Darier sign does not exclude cutaneous mastocytosis either. An image search of Darier Sign can be found here.

Patients can present with pruritis, flushing, and urticaria of the lesions. Some families will say that the size of the lesion varies. With more aggressive lesions, blistering can occur. Triggers usually are mechanical irritation of the lesion, trauma, physical exercise, various food/drink ingestion (e.g. spicy foods, hot beverages), temperature changes (e.g. showers, pools, etc.) medications (anti-inflammatory, antibiotics, opiates, contrast, etc.) and venom such as hymenoptera stings. Anaphylaxis is very uncommon but more likely with systemic mastocytosis. Rarely occurring but oncological progression can happen with systemic mastocytosis. Systemic mastocytosis may present with other problems such as organomegaly, organ pain, organ failure, and problems such as tachycardia or syncope which are part of not full-blown anaphylaxis as well.

Additional information about mast cell disorders can be found here

Questions for Further Discussion
1. What is histiocytosis?
2. What causes brown skin lesions? A review can be found here
3. What causes red skin lesions? A review can be found here
4. How do you treat anaphylaxis?

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for this topic: Skin Pigmentation Disorders

To view current news articles on this topic check Google News.

To view videos related to this topic check YouTube Videos.

Schenck OL, Blechman AB, Kaley JR, Greer KE. Large hyperpigmented plaques on the trunk of a newborn. Cutis. 2017;99(4):230;261;264.

Leung AKC, Lam JM, Leong KF. Childhood Solitary Cutaneous Mastocytoma: Clinical Manifestations, Diagnosis, Evaluation, and Management. Curr Pediatr Rev. 2019;15(1):42-46. doi:10.2174/1573396315666181120163952

Der Sarkissian SA, Sebaratnam DF. Darier sign in mastocytoma. Medical Journal of Australia. 2021;214(5):206-206. doi:10.5694/mja2.50947

Popadic S, Lalosevic J, Lekic B, Gajic-Veljic M, Bonaci-Nikolic B, Nikolic M. Mastocytosis in children: a single-center long-term follow-up study. Int J Dermatol. 2023;62(5):616-620. doi:10.1111/ijd.16612

Author
Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa

Published