What is the best way to describe a single itchy skin lesion with defined borders?

Describing a Single Itchy Lesion with Defined Borders

A single itchy skin lesion with well-defined borders should be described by documenting its size (diameter in centimeters or millimeters), shape (round, oval, or irregular), color characteristics, surface features (scaling, crusting, vesiculation), and the quality of the border (sharp demarcation versus gradual transition). 1

Essential Descriptive Elements

Border Characteristics

• Document whether borders are sharply demarcated or gradually blend into surrounding skin - this is a critical distinguishing feature that helps differentiate between various dermatologic conditions 1
• Note if borders are regular (smooth, circular/oval) versus irregular (jagged, notched, or asymmetric) 1
• Irregular borders with asymmetry raise concern for melanoma and warrant urgent evaluation 1

Size Measurement

• Measure and record the diameter in centimeters or millimeters at the longest axis 1
• Lesions ≥5 cm are more likely to represent erythema migrans from Lyme disease if in appropriate clinical context 1
• Lesions ≥6 mm with other concerning features warrant melanoma evaluation 1
• Mark borders with ink and reassess in 24-48 hours if uncertain whether lesion is expanding 1

Color and Pigmentation

• Document whether the lesion is erythematous, hyperpigmented, hypopigmented, or demonstrates color heterogeneity 1
• Multiple shades of brown and black within a single lesion suggest melanoma 1
• Homogeneous erythema versus central clearing or target-like appearance helps distinguish conditions like erythema migrans 1

Surface Characteristics

• Note presence or absence of scaling - scaling suggests eczematous processes or chronic lesions 1, 2
• Document any vesicles, pustules, crusting, or oozing - these indicate acute inflammatory processes 1
• Vesicular lesions without significant pruritus may represent erythema migrans rather than contact dermatitis 1
• Lichenification (thickened skin with accentuated markings) indicates chronicity 1, 3

Pruritus Quality

• Quantify itch intensity using a 0-10 scale where 0 is no itch and 10 is maximal itching 1
• Mild itch is common in many conditions; intense pruritus suggests atopic dermatitis, contact dermatitis, or bullous pemphigoid 1
• Burning, stinging, or tingling accompanying itch suggests neuropathic origin 1

Critical Pitfalls to Avoid

Do Not Overlook Red Flags

• Any lesion with irregular borders, color heterogeneity, diameter >6 mm, and recent evolution requires melanoma evaluation 1
• Inflammation (reddish tinge), crusting, oozing, or bleeding in a pigmented lesion are concerning features 1
• Painful lesions lasting >48 hours with systemic symptoms may indicate urticarial vasculitis requiring biopsy 4

Context-Dependent Interpretation

• A lesion present while a tick is attached or developing within 48 hours of tick removal is likely hypersensitivity, not erythema migrans 1
• Lesions in unusual locations for cellulitis (axilla, popliteal fossa, abdomen) favor erythema migrans over bacterial infection 1
• Diaper area involvement in infants is rarely atopic dermatitis 3

Documentation Standards

• Photograph the lesion if possible and mark borders to track evolution 1
• Record anatomic location precisely using standard terminology 1
• Note any associated symptoms beyond pruritus (pain, burning, numbness) 1

Algorithmic Approach to Description

1. Measure diameter at longest axis in cm/mm 1
2. Assess border quality: sharp/defined versus blurred/gradual 1
3. Evaluate border regularity: smooth/round versus irregular/asymmetric 1
4. Document color: homogeneous versus heterogeneous, specific hues present 1
5. Examine surface: flat versus raised, presence of scale/vesicles/crust 1
6. Quantify pruritus: 0-10 scale, quality of sensation 1
7. Note evolution: stable, expanding, or changing over 24-48 hours 1