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A 4-month-old with rash on torso
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A 4-month-old accompanied his mother with history of a rash on his trunk. Mother reports no symptoms such as shortness of breath, diarrhea, joint swelling or fever. Baby is otherwise healthy. On examination, there are multiple macules ranging in color from tan to yellow to red (Figure 1). Urtication and erythema surrounded one of the macules after gentle scratching. A punch biopsy was done (Figure 2).
Results of the punch biopsy reveal dense mast cell infiltration in the perivascular and interstitial areas.
Can you spot the rash?
Diagnosis: Mastocytosis
Mastocytosis: accumulation of mast cells in the skin and other organs. WHO consensus classification includes: 1) cutaneous mastocytosis, a benign disease in which mast cell infiltration is confined to the skin; seen in young children with a tendency to regress spontaneously; 2) systemic mastocytosis, mainly in adults; involves at least one extracutaneous organ; and 3) extracutaneous mastocytoma, either presenting as benign mastocytoma or malignant mast cell sarcoma.
On examination, there are multiple macules ranging in color from tan to yellow to red (left figure). Urtication and erythema surrounded one of the macules after gentle scratching. A punch biopsy was done (right figure).
Image:Philip A
Mutations in c-kit are considered to play a key role in the pathogenesis of mastocytosis.
Several forms of cutaneous mastocytosis exist. Urticaria pigmentosa typically presents in early childhood, with 50% of cases occurring in those aged younger than 6 months. Few to numerous macules, papules, nodules and vesicles with variable tan to grey pigmentation may be present.
Mast cell degranulation must be avoided in extensive cases to prevent possible anaphylaxis. Chemicals that induce mast cell degranulation include alcohol, aspirin, opiates, scopolamine, amphotericin B and tubocurarine, among others. Pruritus, diarrhea, shortness of breath, joint pains and fatigue are variably present. Mild trauma such as scratching or rubbing usually leads to itching and urtication with surrounding erythema (Darier’s sign).
Solitary mastocytoma is a single nodular accumulation of mast cells.
Diffuse cutaneous mastocytosis is characterized by diffuse involvement of the entire skin surface.
Treatment is not usually recommended because spontaneous resolution occurs in most cases without systemic disease. Relief of pruritus with antihistamines is considered first-line symptomatic treatment. Other treatment options include photochemotherapy (UVA light and psoralen) or topical corticosteroids.
For more information:
Joseph Philip Peter, MD, and Katherine Swan, MPAS, PA-C, are from Crestview Pediatrics and Adolescent Center, a private practice in Crestview, Fla. Joseph Philip Peter, MD, can be reached at: Crestview Pediatrics & Adolescent Center, 332 Medcrest Drive, Crestview, FL 32536.
Disclosure: Peter and Swan report no relevant financial disclosures.