Why Are My Knees Purple?

The appearance of purple skin on your knees warrants attention as it can sometimes indicate an underlying medical condition. The most concerning reason for purple knees could be dermatomyositis, though other possibilities exist.

Here's a breakdown of potential causes:

• Dermatomyositis:

  • This is an inflammatory disease that affects the muscles and skin.
  • A key sign is the presence of purple or violaceous plaques (flat, raised patches) on the knees. This specific skin manifestation is known as Gottron's sign. Unlike lesions associated with many other diseases, which tend to be red, Gottron's sign is characteristically purple.
  • Other symptoms of dermatomyositis may include muscle weakness, fatigue, and a rash on other parts of the body.

• Other Potential Causes:

  • Bruising: Trauma or injury to the knee area could cause bruising, resulting in a purple discoloration.
  • Poor Circulation: Conditions that impair blood flow to the legs and knees might lead to a bluish or purplish hue.
  • Vasculitis: Inflammation of blood vessels (vasculitis) could also cause skin changes, including purple discoloration.
  • Medications: Certain medications can rarely cause skin discoloration.
  • Hyperpigmentation: Though less common, abnormal pigment deposition could lead to darkening of the skin. However, this is less likely to appear abruptly as purple.

What to Do:

• Consult a Doctor: It is crucial to see a doctor or dermatologist promptly. They can evaluate your symptoms, perform a physical exam, and order appropriate tests to determine the cause of the purple discoloration. Early diagnosis and treatment of dermatomyositis, in particular, are important to manage the disease effectively.
• Provide Information: Be prepared to tell your doctor about any other symptoms you're experiencing, any medications you're taking, and any recent injuries to your knees.

In summary, while a bruise is a common and benign cause of purple knees, the possibility of dermatomyositis warrants immediate medical evaluation. Don't delay seeking professional medical advice.