Diagnostic evaluation
Following a thorough history and physical exam, the diagnosis of cutaneous mastocytosis can be made based on clinical findings.5 It can be confirmed by a punch biopsy of the lesion and measurement of serum tryptase levels; higher levels have been shown to correlate to the number of mast cells in the skin and the child’s cutaneous disease burden.2,4 Ordering baseline tryptase levels can also help distinguish children at risk for severe episodes of mast cell activation from those who may just have a mild case.6
If the patient exhibits symptoms suggestive of systemic mastocytosis (an abnormal increase in mast cells in extracutaneous organs, including bone marrow) or there is suspicion for malignancy, efforts must be made to rule out these more serious diagnoses. A complete white blood cell count with differential, metabolic profile with liver enzymes, and sedimentation rate should be obtained.4
Treatment
The treatment of cutaneous mastocytosis is symptomatic, as it is typically a benign disease. The goal of therapy is to prevent mast cell activation, and hence the symptoms that occur when mast cells release their mediators, by avoiding obvious triggers.4
NSAIDs have been reported to cause mast cell mediator release and should therefore be avoided. Since extremes in temperature—particularly heat—can lead to mast cell activation, it is important to control the temperature of a bath or swimming pool and to be wary of exposure to air conditioning. Though easier said than done, soothing crying babies and children is also helpful, as irritability is a known trigger. Management of anxiety and avoidance of stress when possible is recommended.2
Treatment usually begins with H1 and H2 blockers. Cetirizine and diphenhydramine work to control the itching, while ranitidine and famotidine help manage gastric acid secretion when there are symptoms of abdominal pain and peptic ulcer disease.3 Hydroxyzine is effective in controlling both itch and gastric acid secretion.4 Water-soluble cromolyn sodium cream helps to decrease the itch and flare of a mastocytoma; the oral form is also effective.3 Another option to relieve itching is to apply topical corticosteroids with an occlusive dressing.
An epinephrine auto-injector is recommended due to the risk for anaphylaxis; this risk, however, has not been clearly established in cutaneous mastocytosis, specifically in DCM. During an acute and severe flare that induces hypotension, wheezing, and/or laryngeal edema, epinephrine should be administered while the child is lying down.3,4
Surgical excision can be considered when other treatment options fail, or if the lesion is located on the scalp, flexure area, palm, or sole.3,4