Resident Editor: Janet Chu, M.D.
Faculty Editor: Ryan Arakaki, M.D.
BOTTOM LINE ✔ Accurately categorizing morphology and distribution is essential ✔ Cutaneous findings can often signal and reveal underlying systemic diseases |
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
Primary Lesion |
Definition |
Macule |
Nonpalpable, <0.5 cm in diameter |
Patch |
Nonpalpable, >0.5 cm in diameter |
Papule |
Palpable, <0.5 cm in diameter |
Plaque |
Palpable, >0.5 cm in diameter |
Nodule |
A palpable lesion that has a significant vertical component, generally > 1cm |
Vesicle |
Fluid-filled, <0.5 cm (fluid can be serosanguinous, hemorrhagic, purulent) |
Bullae |
Fluid-filled, >0.5 cm (fluid can be serosanguinous, hemorrhagic, purulent) |
Pustule |
Small (usually < 1cm) elevated lesion containing purulent material |
Cyst |
Firm, well-circumscribed lesion containing liquid or semisolid material |
Secondary Change |
Definition |
Erosion |
Loss of superficial epidermis |
Ulcer |
Loss of epidermis and part or all of dermis |
Scale |
Visible fragment of stratum corneum when shed from the skin |
Crust |
Dried liquid debris (serosanguinous or hemorrhagic) overlying skin lesion |
Lichenification |
Thickening of skin and accentuation of skin markings (indicates rubbing or scratching) |
Atrophy |
Fine, cigarette-paper like wrinkling, the epidermis may have semi-translucent quality |