Primary skin lesions

   Primary skin lesions are the initial, direct result of a skin pathology or disease process. They are categorized based on their appearance, size, and content. Below is a detailed explanation of primary skin lesions

1. Macule

Definition: A flat, non-palpable, discolored area of skin, usually less than 1 cm in diameter.

Example: Freckles, vitiligo patches.

Key Point: No change in skin texture or thickness.

2. Patch

Definition: A flat, non-palpable discoloration, similar to a macule but larger than 1 cm.

Example: Larger vitiligo patches, café-au-lait spots.

3. Papule

Definition: A raised, solid lesion less than 1 cm in diameter.

Example: Warts, insect bites.

Key Point: Palpable and well-defined.

4. Plaque

Definition: A raised, flat-topped lesion greater than 1 cm in diameter.

Example: Psoriasis plaques.

Key Point: Often formed by the coalescence of papules.

5. Nodule

Definition: A firm, raised lesion deeper in the dermis, greater than 1 cm in diameter.

Example: Lipomas, erythema nodosum.

6. Tumor

Definition: A large nodule, which can be benign or malignant.

Example: Fibromas, skin cancer lesions.

Key Point: Larger than 2 cm in diameter.

7. Vesicle

Definition: A small, fluid-filled blister less than 1 cm in diameter.

Example: Herpes simplex lesions, chickenpox vesicles.

8. Bulla

Definition: A large, fluid-filled blister greater than 1 cm in diameter.

Example: Bullous pemphigoid, burns.

9. Pustule

Definition: A small, raised lesion filled with pus.

Example: Acne pustules, impetigo.

10. Wheal

Definition: A transient, raised, erythematous lesion caused by dermal edema.

Example: Urticaria (hives), insect stings.

11. Cyst

Definition: A closed sac filled with liquid or semi-solid material, located deeper in the dermis or subcutaneous layer.

Example: Sebaceous cysts, epidermoid cysts.