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Mastocytosis in adults
Other Resources UpToDate PubMed

Mastocytosis in adults

Contributors: Erin X. Wei MD, Belinda Tan MD, PhD, Noah Craft MD, PhD, Susan Burgin MD
Other Resources UpToDate PubMed


Mastocytosis is a term broadly referring to tissue mast cell hyperplasia. This proliferation is generally classified as either cutaneous, with or without systemic involvement, or systemic without cutaneous disease. Mastocytosis most commonly manifests as cutaneous disease (urticaria pigmentosa, mastocytoma), seen more often in children with involvement typically limited to the skin. In contrast, adult cutaneous variants frequently have systemic disease. 

Systemic mastocytosis is a less common myeloproliferative variant that is further stratified based on clinical criteria as well as on associated mutations, namely activating c-kit mutations. In general, there is no age or sex predilection.

The 2016 World Health Organization (WHO) classification includes:
  • Cutaneous mastocytosis:
    1. Cutaneous mastocytoma
    2. Maculopapular cutaneous mastocytosis (urticaria pigmentosa)
    3. Diffuse mastocytosis
  • Systemic mastocytosis:
    1. Indolent systemic mastocytosis
    2. Smoldering systemic mastocytosis
    3. Systemic mastocytosis with hematologic neoplasm
    4. Aggressive systemic mastocytosis
    5. Mast cell leukemia
    6. Mast cell sarcoma
Patients first need to be assessed to determine whether they have cutaneous mastocytosis or systemic mastocytosis. Cutaneous mastocytosis most commonly affects children. Systemic mastocytosis typically affects adults. All adults with mastocytosis need to have a full workup to exclude systemic mastocytosis.

In adults, cutaneous mastocytosis is defined by:
  1. Typical skin lesions.
  2. Positive Darier sign and/or a positive skin histology.
  3. Absence of criteria sufficient to diagnose systemic mastocytosis in staging examinations.
Once the diagnosis of cutaneous mastocytosis is established, the cutaneous findings can be subclassified as above.


D47.01 – Cutaneous mastocytosis

397016004 – Systemic Mast Cell Disease

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Differential Diagnosis & Pitfalls

Maculopapular cutaneous mastocytosis:
  • Nevus telangiectaticus (eg, Port-wine stain)
  • Glomus tumor
  • CREST syndrome
  • Fabry disease
  • Telangiectasia secondary to underlying liver disease
  • Ephelides
  • Common acquired nevus
  • Poikiloderma vasculare atrophicans
  • Poikiloderma of Civatte – typically seen in the neck region
  • Rosacea – typically seen on the face
  • Generalized essential telangiectasia
  • Urticaria
Systemic mastocytosis:
  • Mast cell activation syndrome – The more recently termed mast cell activation syndrome (MCAS) describes patients who have multiple mast cell mediator-induced symptoms that do not meet the WHO criteria (see Best Tests) for diagnosis of systemic mastocytosis when other underlying diseases have been excluded. 
  • Pheochromocytoma – Patients with an underlying pheochromocytoma present with paroxysms of hypertension, tachycardia, and diaphoresis. Pallor is often seen during these paroxysms, with flushing following resolution of the attack. 
  • Carcinoid syndrome – Patients with foregut carcinoid tumors may suffer from carcinoid syndrome, which classically manifests with GI complaints. Chronic watery diarrhea with associated weight loss is the most frequent complaint; however, patients may also note abdominal pain, constipation, and nausea. A persistent and intense salmon-pink to red flushing occurs in these patients. As opposed to foregut carcinoid tumors, patients with midgut tumors typically demonstrate a more cyanotic flushing. Due to an acquired niacin deficiency, pellagra-like cutaneous symptoms are also seen.
  • Generalized essential telangiectasia 
  • Urticaria

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Last Reviewed:11/05/2023
Last Updated:11/06/2023
Copyright © 2024 VisualDx®. All rights reserved.
Mastocytosis in adults
A medical illustration showing key findings of Mastocytosis in adults (Constitutional)
Clinical image of Mastocytosis in adults - imageId=739466. Click to open in gallery.  caption: 'A myriad of light brown and reddish macules and thin papules, some discrete and some confluent, on the back and arms.'
A myriad of light brown and reddish macules and thin papules, some discrete and some confluent, on the back and arms.
Copyright © 2024 VisualDx®. All rights reserved.