Resident Editor: Janet Chu, M.D.

Faculty Editor: Ryan Arakaki, M.D. 

Background 

• Skin findings can often reveal underlying systemic conditions 
• Accurate diagnosis depends upon the correct categorization of a skin lesion’s morphology and distribution. Incorrect categorization can lead to an incorrect differential diagnosis.  

History

• Description: duration, evolution, distribution, morphology 
• Associated symptoms: pruritus, pain, swelling, warmth  
• Chronic medical conditions: e.g., lupus & other connective tissue disorders, HIV & other immunosuppressed states (such as organ transplant), liquid and solid malignancies 
• Medications: timing of new medications, non-prescribed medications such as OTCs, vitamins, herbal medications, recent chemotherapy 
• Prior treatments: topical and systemic therapies and associated response to therapy 

Physical Exam

• Differential diagnosis is guided by morphology and distribution of the skin lesion(s) 
• Morphology: 
  • Identify primary lesion (see Table 1) 
  • Color 
  • Size 
  • Shape (e.g., round, ovoid, annular, polygonal, linear) 
  • Borders (Well-defined or ill-defined) 
  • Configuration (e.g., grouped, discrete, coalescing) 
  • Secondary changes (e.g., scale, crust, eroded, ulcerated, lichenified) 
  • Lack of secondary change suggests predominantly dermal process 
• Distribution (e.g., photo distributed, flexural surfaces, extensor surfaces, diffuse, acral, mucosal involvement) 

Table 1: Basic Dermatology Terminology