Chapter 1: Introduction to Clinical Dermatology
Morphology: Primary Lesions
Primary Lesions
The primary lesion is the true state of the illness when it first appears or is unchanged by outside forces such as infection or scratching. When evaluating skin disease, it is helpful to find the primary lesions.
| Macule | A flat lesion with no surface change <1cm in diameter. |
| Patch | A flat lesion with no surface change >1cm in diameter. |
| Papule | A raised or scaly lesion <1cm in diameter. |
| Plaque | A raised or scaly lesion >1cm in diameter. |
| Vesicle | A fluid-filled lesion <1cm in diameter. |
| Bullae | A fluid filled lesion >1cm in diameter. Flacid bullae: Thin walled, ruptures easily, rarely seen intact. Tense bullae: Thick walled, appears tense. |
| Pustule | A superficial cavity containing purulent material, usually <1cm in diameter. |
| Nodule | A raised, solid lesion involving the dermis and/or subcutaneous tissue, usually >1cm diameter. |
| Wheal | A transient, elevated lesion due to superficial edema, often pink to red with surrounding pallor. |
| Telangiectasia | Persistent dilation of superficial blood vessels in the skin. |
| Comedone | Plugged secretions of a pilosebaceous unit (a hair follicle and its accompanying sebaceous gland) Open comedone: Small 1-2mm white to skin coloured papule Closed comedone: Small 1-2mm papules with a brown-black central opening. |
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