Introduction to Dermatology | The Basics | Describing Skin Lesions (Primary & Secondary Morphology)

Summary

This introductory dermatology lesson focuses on describing skin lesions using primary and secondary morphology. It covers distinguishing flat versus raised lesions, sizes, and consistencies, such as macules, papules, vesicles, and nodules. The video also explains lesions caused by bleeding under the skin, like petechiae, purpura, and ecchymosis. It touches on secondary morphology aspects like lesion color, texture, and shapes, including terms like annular, linear, and serpiginous. Common skin conditions such as urticaria, ulcers, and hyperkeratosis are discussed, offering a detailed guide for recognizing and describing various skin conditions.

Takeaways

• 🟡 Introduction to dermatology: covering methods of describing skin lesions and common types.
• 🔍 Primary morphology: categorized by whether a lesion is flat or raised, and its size (less or greater than 10mm).
• 📏 Flat lesions less than 10mm are macules; flat lesions greater than 10mm are patches.
• ⬆️ Raised lesions less than 10mm are papules; raised lesions greater than 10mm are plaques.
• 💧 Liquid-filled raised lesions less than 10mm are vesicles, while greater than 10mm are bullae.
• 🧫 Pus-filled raised lesions are pustules, and solid raised lesions are nodules.
• 🩸 Bleeding under the skin results in petechiae (less than 3mm), purpura (3-10mm), and ecchymosis (greater than 10mm).
• 🌡️ Urticaria refers to red, rounded, raised rashes, commonly known as hives.
• 🔄 Secondary morphology focuses on color, shape, texture, and location, with specific terms for shapes like annular (rounded), linear, and serpiginous (snake-like).
• 🧴 Textures of lesions include hyperkeratosis (thickened skin), varicose (irregular raised dark lesions), and indurated (thickening from swelling or edema).

Q & A

What is primary morphology in dermatology?

Primary morphology refers to the initial appearance of a skin lesion, focusing on whether it is flat or raised, its size, and constituency. It helps in categorizing skin lesions as macules, patches, papules, plaques, vesicles, and others.

How do you differentiate between a macule and a patch?

Both macules and patches are flat skin lesions, but a macule is less than 10 millimeters in size, while a patch is greater than 10 millimeters.

What terms are used to describe raised skin lesions, and how are they categorized?

Raised skin lesions are categorized by size and contents. If less than 10 millimeters, it's a papule; if greater than 10 millimeters, it's a plaque. If liquid-filled, small ones are called vesicles, and larger ones are bullae. Pus-filled lesions are pustules, while solid raised lesions are nodules.

What is the difference between vesicles and bullae?

Vesicles are raised, liquid-filled lesions that are less than 10 millimeters in size, while bullae are larger, liquid-filled lesions greater than 10 millimeters.

What are petechiae, purpura, and ecchymosis, and how are they related to bleeding under the skin?

Petechiae are small, non-palpable lesions caused by bleeding under the skin, less than 3 millimeters in size. Purpura are larger areas of hemorrhage, 3-10 millimeters, which may or may not be palpable. Ecchymosis is a large, non-palpable area of bleeding greater than 10 millimeters.

What is urticaria and what causes it?

Urticaria, also known as hives, is a red, raised, round rash caused by allergic reactions. It's characterized by redness, swelling, and itching.

What is the difference between an ulcer and an erosion?

An ulcer is a larger skin lesion that affects both the epidermis and part of the dermis, while an erosion only involves the epidermis, the top layer of the skin.

What does 'non-blanchable' mean in the context of skin lesions?

Non-blanchable refers to skin lesions that do not lose their color when pressure is applied. This is common in bleeding under the skin, like petechiae, purpura, and ecchymosis.

What does the term 'telangiectasia' refer to?

Telangiectasia refers to small, dilated blood vessels near the skin's surface. These are visible as red or purple lines on the skin.

How do secondary morphologies help describe skin lesions?

Secondary morphologies provide further details about skin lesions, including their color, shape (e.g., round, linear, coin-shaped), texture (e.g., rough, smooth), and location. This helps in more accurately identifying and diagnosing skin conditions.