Skin nonmelanocytic tumor

Lymphoma and related disorders (see also Lymphoma chapter)


Cutaneous mastocytosis

Topic Completed: 1 July 2012

Minor changes: 15 October 2020

Copyright: 2003-2021,, Inc.

PubMed search: Mast cell disorders [title] skin

Christopher S. Hale, M.D.
Mowafak Hamodat, M.B.Ch.B., M.Sc.
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Cite this page: Hale CS., Hamodat M. Cutaneous mastocytosis. website. Accessed December 3rd, 2021.
Definition / general
  • Most cutaneous mast cell disorders have a good prognosis
  • Mastocytosis: monomorphic population of mast cells with rare eosinophils
  • Telangiectasia macularis eruptive perstans (TMEP): telangiectatic light or dark brown macules
  • Urticaria pigmentosa: common form of mastocytosis, numerous small yellow brown papules, become hives when rubbed
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

Contributed by Mark R. Wick, M.D.

Breast skin

Images hosted on other servers:

Erythematous macules with telangiectasia

Telangiectatic macules in the scapular area

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 #344


Toluidine blue

Positive stains
Differential diagnosis
  • Normal skin or dermatoses: must search to find mast cells even with special stains
  • Chronic dermatitis, nodular prurigo, and venous stasis: typically associated with granulation tissue and foci of neovascularization
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