Differential Diagnosis for Redness in Lower Limbs
Single Most Likely Diagnosis
- Cellulitis: This is a common bacterial skin infection that can cause redness, swelling, and warmth in the affected area, often accompanied by fever and malaise. The lower limbs are a frequent site for cellulitis due to factors like trauma, poor circulation, or immune compromise.
Other Likely Diagnoses
- Eczema/Dermatitis: Conditions like atopic dermatitis, contact dermatitis, or stasis dermatitis can cause redness and inflammation in the lower limbs. These conditions often have a chronic course and may be associated with itching.
- Varicose Eczema: Related to poor venous circulation, this condition leads to skin changes including redness, itching, and sometimes ulceration, typically around the ankles.
- Insect Bites or Stings: Reactions to insect bites or stings can cause localized redness, swelling, and itching in the lower limbs.
Do Not Miss Diagnoses
- Deep Vein Thrombosis (DVT): Although DVT typically presents with swelling and pain, it can sometimes cause redness and warmth in the affected limb. Missing this diagnosis can be fatal due to the risk of pulmonary embolism.
- Erythema Nodosum: A condition characterized by the sudden formation of painful, red nodules under the skin, often on the shins. It can be associated with various underlying conditions, including infections, autoimmune diseases, and medications.
- Necrotizing Fasciitis: A severe infection that destroys tissue under the skin, including fat and the tissue covering the muscles (fascia). It requires immediate medical attention and can be fatal if not treated promptly.
Rare Diagnoses
- Erythromelalgia: A disorder characterized by burning pain, heat, and redness in the hands and feet. It can be primary (genetic) or secondary to other conditions like myeloproliferative disorders.
- Chilblains: A condition that occurs in response to cold temperatures, causing small blood vessels in the hands and feet to become inflamed, leading to redness, itching, and sometimes ulcers.
- Livedo Reticularis: A mottled, purplish discoloration of the skin, typically on the legs, which can be associated with various conditions, including vasculitis, autoimmune diseases, and cold agglutinins.