Skin inflammatory (nontumor)
Dermal non-granulomatous granulocyte-rich reaction patterns
Mastocytosis of skin

Topic Completed: 1 August 2011

Minor changes: 27 March 2019

Copyright: 2002-2019,, Inc.

PubMed Search: Mastocytosis [title] skin

Mowafak Hamodat, M.B.Ch.B., M.Sc.
Page views in 2019: 7,862
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Cite this page: Hamodat M Mastocytosis of skin. website. Accessed June 7th, 2020.
Definition / general
  • Either urticaria pigmentosa, solitary mastocytoma, diffuse and erythrodermic cutaneous mastocytosis or telangiectasia macularis eruptiva perstans
Clinical features
  • At birth or during the first 3 months of life
  • May present with flushing attacks due to high histamine content
  • Spontaneous involution frequently occurs
  • CD117 mutations in patients with mastocytosis
  • Urticaria pigmentosa: most common form of mastocytosis of skin; usually childhood onset of multiple brown macules; systemic variant is malignant and involves liver, spleen, bone marrow, lymph nodes and occasionally peripheral blood (mast cell leukemia)
  • Darier's sign: stroking skin releases histamine, causing hives
  • Dermatographism: dermal edema resembling hives due to stroking with pointed instrument

  • Description:
    • Solitary lesion, or small group as part of urticaria pigmentosa
    • Affect extremities and trunk, not palms and soles
    • May blister
    • Red, brown pink or yellow nodules, or plaques measuring up to 1.0 cm
Case reports
Clinical images

Images hosted on other servers:

Various images

Urticaria pigmentosa


Microscopic (histologic) description
  • Within the macules and plaque, mast cells are predominantly in papillary dermis
  • Mast cells are round or spindle shaped with abundant eosinophilic cytoplasm, distinct cytoplasmic boundaries, large pale nuclei
  • Eosinophils are often present
  • Also edema of papillary dermis, subepidermal vesiculation
  • Bullous mastocytosis may be diagnosed by Tzank smear; infiltrate may be slight and perivascular
  • In telangiectasia macularis eruptive perstans, features may be subtle, with increased mast cells around dilated superficial capillaries, basal cell hyperpigmentation of overlying epidermis, superficial lymphohistiocytic infiltrate
Microscopic (histologic) images

Contributed by Mark R. Wick, M.D





Toluidine blue


Breast skin

Urticaria pigmentosa, breast skin

Leder stain, breast

Case of the Week #344


Toluidine blue

Positive stains
Differential diagnosis
  • Chronic dermatitis, nodular prurigo, and venous stasis: typically associated with granulation tissue and foci of neovascularization
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