Dermatology is the branch of medicine dedicated to diagnosing and treating conditions of the skin, hair, nails, and mucous membranes. It covers everything from common rashes and acne to skin cancer detection and cosmetic procedures. About 6 million people in the U.S. are treated for some form of skin cancer each year alone, making dermatology one of the most widely encountered medical specialties.
What Dermatology Covers
The skin is the body’s largest organ, and dermatology’s scope extends well beyond its surface. The field encompasses hair disorders, nail conditions, and even the mucous membranes of the mouth and genitals. A standardized anatomical vocabulary developed through international consensus includes 513 unique terms organized across nine levels of detail, reflecting just how precisely dermatologists map the body’s surface when examining and treating patients.
The conditions dermatologists manage fall into three broad categories. Medical dermatology focuses on diseases: eczema (atopic dermatitis), acne, warts, skin infections and abscesses, psoriasis, and benign or malignant growths. Surgical dermatology involves removing skin cancers, cysts, and other lesions. Cosmetic dermatology addresses appearance, including injectable treatments, laser procedures for scarring or sun damage, and anti-aging skincare regimens. A single dermatologist may practice across all three areas or specialize in one.
Common Conditions Dermatologists Treat
The conditions that bring people to a dermatologist most often are atopic dermatitis (eczema), acne, skin infections and abscesses, warts, and benign skin growths like moles and cysts. Many of these overlap with what primary care doctors see, but dermatologists bring specialized tools and training to cases that are persistent, unusual, or potentially dangerous.
Skin cancer is among the most serious conditions in dermatology’s scope. In 2021, over 90,000 Americans were diagnosed with melanoma, the deadliest form of skin cancer, and roughly 8,000 people die from it each year. Early detection through regular skin exams is one of dermatology’s most important public health contributions, since melanoma caught early has a far better prognosis than melanoma that has spread.
Chronic inflammatory diseases like psoriasis and severe eczema have also become a major focus. These conditions involve an overactive immune response in the skin, and newer biologic therapies can now target specific parts of that immune process. Some biologics block the inflammation-driving proteins that cause skin cells to proliferate too quickly, while others prevent certain immune cells from migrating into the skin in the first place. These treatments have transformed outcomes for patients who previously cycled through creams and pills without lasting relief.
How Dermatologists Diagnose Skin Conditions
Dermatologists rely on a mix of non-invasive and invasive techniques. The most common non-invasive tool is dermoscopy, a handheld device with magnification and polarized light that lets a dermatologist see structures beneath the skin’s surface invisible to the naked eye. Dermoscopy helps distinguish a harmless mole from a potentially cancerous one and can often confirm a diagnosis without any cutting at all.
When dermoscopy isn’t conclusive, a skin biopsy remains the gold standard. A small sample of tissue is removed, processed, and examined under a microscope. Dermoscopy also guides where to biopsy, helping the dermatologist target the most suspicious area of a lesion rather than sampling blindly. Other diagnostic methods include scraping the skin surface to test for fungal infections and clipping nails or pulling hairs for microscopic evaluation.
Mohs Surgery and Skin Cancer Removal
One of dermatology’s most precise surgical techniques is Mohs micrographic surgery, used primarily for skin cancers with a high risk of recurrence or those located in areas where preserving healthy tissue matters most: the face, ears, eyelids, nose, lips, hands, feet, and genitals. The procedure is performed in stages while the patient waits.
First, the visible tumor is outlined and removed. Then a thin layer of surrounding tissue is taken at a 45-degree angle, divided into sections, color-coded, and mapped. That tissue is frozen, sliced horizontally, and examined under a microscope so that virtually 100% of the outer and deep margins can be checked for remaining cancer cells. If any cancer remains, the map tells the surgeon exactly where to go back and remove more. This cycle repeats until the margins are clear, then the wound is closed with stitches, a skin flap, or a graft. The result is complete tumor removal with the smallest possible loss of healthy skin.
How to Become a Dermatologist
Becoming a board-certified dermatologist requires a minimum of 12 years of education and training after high school. That includes four years of college, four years of medical school, and four years of postgraduate training. The first postgraduate year is a clinical internship in a field like internal medicine, surgery, pediatrics, or emergency medicine. The remaining three years are spent in a dermatology-specific residency program accredited by the Accreditation Council for Graduate Medical Education (ACGME).
Dermatology residencies are among the most competitive in medicine. After completing training, physicians sit for a certification exam administered by the American Board of Dermatology, whose stated mission is to set high standards for dermatologists to earn and maintain board certification.
Recognized Subspecialties
After completing a general dermatology residency, some dermatologists pursue additional fellowship training in one of three ACGME-accredited subspecialties:
- Dermatopathology: The microscopic study of skin tissue samples, combining expertise in both dermatology and pathology to diagnose diseases at the cellular level.
- Micrographic Surgery and Dermatologic Oncology: Advanced training in Mohs surgery and the management of skin cancers. Starting in 2026, all dermatologists must complete an accredited fellowship in this area before taking the subspecialty certification exam.
- Pediatric Dermatology: Focused on skin conditions unique to or common in infants, children, and adolescents, including birthmarks, genetic skin disorders, and childhood eczema.
Medical vs. Cosmetic Dermatology
The simplest way to understand the split: medical dermatology aims to cure disease and protect skin health, while cosmetic dermatology aims to improve appearance. A medical dermatologist is who you see for a suspicious mole, a painful rash, or a skin infection. A cosmetic dermatologist is who you see for wrinkle-reducing injectables, laser treatments to fade acne scars or spider veins, or guidance on anti-aging skincare products.
In practice, the line blurs frequently. Treating severe acne is medical dermatology, but addressing the scars it leaves behind is often cosmetic. Many dermatologists offer both, and the training is the same. The distinction matters most for insurance: medical dermatology visits are typically covered, while cosmetic procedures generally are not.