urticaria pigmentosa (UP)

Introduction

A generalized cutaneous mastocytosis.

Epidemiology

onset between birth & 2 years of age

Clinical manifestations

• slightly tan macules to slightly raised papules/nodules
• dermatographism
• bright red flushing
  • spontaneous
  • following rubbing of skin
  • ingestion of alcohol or other mast-cell degranulating agents
• widespread symmetric distribution
• a few to > 100 lesions

Differential diagnosis

• Histiocytosis
• secondary syphilis
• sarcoid
• histiocytoma
• non-X histiocytosis

More general terms

• mastocytosis

Additional terms

• Darier's sign
• dermatographism