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Serum Tryptase Levels in 114 Pediatric Patients with Cutaneous Mastocytosis
Saturday, March 3, 2018: 2:45 PM
S230EF (Convention Center)
Neha Seth, MD, , , , ,
RATIONALE: Cutaneous mastocytosis (CM) is classified into mastocytoma (M), urticaria pigmentosa (UP) renamed maculopapular CM (MPCM) and diffuse cutaneous mastocytosis (DCM). Serum tryptase level is a marker of mast cell burden and helps assess risk of systemic manifestations. Elevated levels often prompt studying internal organ involvement. We examined tryptase levels in pediatric CM patients.

METHODS: Retrospective review of CM patients seen at Texas Children’s Hospital from January 2006 to August 2017. Patients with CM diagnosis and positive Darier’s sign were included.

RESULTS: We identified 114 CM patients. There were 60 males and 54 females. Median age was 4 years (5 months-17 years). One hundred and two (89%) patients were diagnosed with UP, 10 (8.7%) with M and 4 (3.5%) with DCM. According to CM type, UP and M patients had median tryptase level of 5.6 ng/ml (2-19 ng/ml; normal < 10 ng/ml), and values for DCM patients were 18, 75, 160 and 283 ng/ml. Serum tryptase level was between 10-20 ng/mL in seven UP patients. Twelve (10.7%) patients with UP and M had systemic symptoms: pruritus, flushing, diarrhea. Only 3 of these patients with systemic symptoms had elevated tryptase. Bone marrow biopsy performed in one patient was normal. C-kit mutation was positive on skin biopsy in one patient but was not associated with elevated tryptase.

CONCLUSIONS: Serum tryptase levels obtained in this large cohort support the recommendation of limiting investigations for systemic mast cell disease in pediatric CM patients with serum tryptase < 20 ng/mL.