Clinical Approach to MCAS Diagnosis and Cutaneous Mastocytosis

Children 

Adults

Average age at onset 

< 2 years [27, 35-37] 

36 years [38]

Associated with SM 

- Rarely

- Consider bone marrow biopsy if:

- Usually

- BM bx in most cases, especially if tryptase > 20 

- Hepatosplenomegaly,  lymphadenopathy 

- Tryptase > 100 mg/dL or  rising over time 

- Severe systemic symptoms 

- D816V mutation in peripheral blood

mg/dL, there is presence of systemic disease and/or MCA [1]

Maculopapular CM

- Monomorphic 

- Polymorphic

70-90% [27, 35, 36]

- Less common [1] 

- More common [1]

Typical 

- More common [1] 

- Rare

Mastocytoma 

10-35% [27, 35, 36] 

Exceptionally rare

Diffuse CM (DCM) 

Rare (1-5%) [27, 35, 36] 

Exceptionally rare

D816V 

27-43% [27, 35, 36, 39] 

80-90% [4, 35, 36]

Elevated serum tryptase 

- Rare in CM and mastocytoma

- Common in DCM [27]

Systemic symptoms (pruritus, flushing, GI)

20-65%, especially in DCM [27, 35, 36]

Common

Anaphylaxis 

< 10% (usually in DCM) [35, 36, 40]

50% [40]