Dermatology is the branch of medicine concerned with the skin, hair, and nails, as well as the conditions associated with them. Basic knowledge of dermatology is essential for every physician, as approximately 50% of skin-related consultations are initially assessed by non-dermatologists. In the United States, the most common conditions seen by dermatologists include acne, actinic keratoses, non-melanoma skin cancers, benign tumors, and contact dermatitis. Skin lesions may be primary or secondary. Primary lesions (e.g., macules or papules) appear as a direct result of a disease process. Secondary lesions such as scales or ulcers may develop from primary lesions or result from external trauma (e.g., infections, scratching). Dermatological conditions can often be diagnosed based on patient history and physical examination but may require laboratory testing or biopsy to confirm the diagnosis. Dermatological diseases are managed with medication (topical and systemic) and procedures such as surgery, cryotherapy, radiotherapy, or phototherapy. Topical treatments are often the first choice because they cause fewer systemic side effects and are easily administered.
- Chief complaint: Begin with open-ended question to address the patient's main concerns.
- History of present illness
- Past medical history: Underlying diseases may be responsible for skin findings (e.g., erythema nodosum in chronic bowel disease).
- Drug history: Drug interactions may lead to skin irritations, so it is important to note any changes in the patient's drug regimen.
- Review of systems: Diseases such as diabetes, rheumatic diseases, infections, and endocrine disorders (hyperthyroidism) may lead to skin conditions.
- "Café au lait" spots in young children may be part of an inherited disease such as neurofibromatosis.
- Taking a family history of skin diseases helps to determine the correct diagnosis.
- Social history
- Goal: Examine the skin (including of the hands, mouth, and scalp) and nails to help in determining a working diagnosis or differentials and any potential diagnostic/management steps based on observations.
- Examination techniques
The hands, mouth, scalp, and nails should not be overlooked during a dermatological examination.
Skin examination 
- Determine the type of lesion: See primary skin lesions, secondary skin lesions, and complex skin lesions below.
- Describe lesion characteristics
|Alterations of the nails|
|Clinical findings||Possible underlying disease|
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|Alterations of the hands|
|Exam technique||Clinical findings||Possible underlying disease|
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Many systemic diseases can manifest with findings on the patient's hands.
|Overview of most common primary skin lesions|
|Nodule (dermatology)|| |
|Overview of most common secondary skin lesions|
|Excoriation (scratch marks)|
|Overview of complex skin lesions |
|Subtypes of hematomas = purpura||Nonpalpable purpura|| |
|Ecchymosis || |
| Palpable purpura || |
|Hypergranulosis|| || |
|Hyperkeratosis|| || |
Overview of management steps
The external nature of the skin allows a variety of treatment options, including:
- Systemic medications
- Topical medications
- Physical procedures
Types of topical preparations 
Drugs must be absorbed into the skin to be effective, so choosing the proper type of topical preparation for the pharmacological agent is important. Examples include:
- Lotions, foams, and gels
Topical steroids are the most frequently used topical treatment in dermatology.