Patch dermatology refers to the study and treatment of skin lesions called patches. A patch is defined as a large, flat area of discoloration on the skin, greater than 1 cm in diameter. It's a type of macule, meaning it's non-palpable (not raised above the skin surface).
Understanding Patches
Patches are characterized by their:
- Size: Larger than 1 centimeter in diameter.
- Shape: Irregular or well-defined.
- Texture: Flat and smooth.
- Color: Varies depending on the cause, ranging from brown or red to hypopigmented (lighter than surrounding skin).
Examples of Patches
Several conditions can manifest as patches on the skin. Examples include:
- Freckles: Small, brown patches caused by sun exposure.
- Flat moles (Nevi): Usually brown or black, ranging in size and shape.
- Tattoos: Permanent pigmentation of the skin.
- Port-wine stains: Flat, reddish-purple birthmarks.
- Infectious rashes: Patches seen in conditions like rubella, measles (often accompanied by other lesions), and rickettsial infections.
- Allergic drug eruptions: Patches that develop as a reaction to medication.
Diagnosis and Treatment
Diagnosing the cause of a patch requires a thorough examination by a dermatologist. The doctor will consider the patient's medical history, the patch's appearance, location, and any associated symptoms. Treatment varies depending on the underlying cause, ranging from simple observation to medical intervention. For example, treatment of a port-wine stain might involve laser therapy, while an allergic drug eruption requires discontinuation of the offending medication.
