Cutaneous Mastocytosis

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With grateful thanks to Nancy Gould

The type in light blue is an easy to read translation

CUTANEOUS MASTOCYTOSIS — Cutaneous mastocytosis is an infiltrative skin disorder that can present with blisters in the newborn. The two main forms are urticaria pigmentosa (UP), which may consist of solitary or multiple lesions, and more rarely, diffuse cutaneous mastocytosis.

UP lesions consist of red-brown macules (small, flat spots), papules (small raised spots), and plaques (large flat or raised spots) that are distributed diffusely (all over the body) but are most commonly concentrated on the trunk. Palms and soles are generally not involved. Lesions urticate (form a hive) with rubbing or scratching (Darier's sign) as a result of mast cell degranulation(release of mast cell chemicals that are stored in granules inside the mast cell) and release of vasoactive substances (chemicals that cause blood vessels to change size). In newborns, UP lesions are more likely to blister or present as a mastocytoma, a firm solitary (benign) tumor

In diffuse cutaneous mastocytosis, large numbers of mast cells infiltrate the skin over large areas, causing round, tense bullae (blisters) and the development of thickened, leathery skin with accentuated markings. Darier's sign is also present. The skin lesions may be accompanied by flushing, hypotension (low blood pressure), wheezing, diarrhea, and gastrointestinal bleeding.

The clinical diagnosis is confirmed with skin biopsy that demonstrates dermal mast cell infiltrates (mast cells present in the deep layer of skin)   The mast cell infiltrates may be maximized by injecting local anesthesia without epinephrine adjacent to the lesion. (they mean that when a biopsy of a lesion is taken, the number of visible mast cells may be increased if a local anesthetic without epinephrine – adrenaline – is injected close to the place to be biopsied.  This keeps the mast cell granules from releasing their chemicals, allowing mast cells to be identified by the large number of granules inside the cell.)

Most patients with onset of cutaneous mast cell disease in infancy spontaneously improve or have total resolution by adolescence, with a low risk of involvement of other organs.(Most infants with skin mastocytosis will outgrow their disease, and it is very unlikely to turn into systemic mastocytosis) Symptomatic treatment of more extensive disease includes avoidance of histamine releasing medications such as opiates, aspirin, NSAIDS, and alcohol, and avoidance of exposure to extremes of temperature, as well as the use of antihistamines (H1 and H2 blockers), topical or intralesional (injected into individual spots), corticosteroids or oral cromolyn