Differential Diagnosis for Skin Lesions

The following differential diagnosis is organized into categories to help guide the thought process:

• Single Most Likely Diagnosis

  • Eczema (atopic dermatitis): This is a common condition characterized by itchy, inflamed skin, and is often seen in individuals with a history of allergies or asthma. The presentation of skin lesions, especially if they are itchy and located in typical areas such as the face, hands, or inside the elbows, makes eczema a likely diagnosis.

• Other Likely Diagnoses

  • Psoriasis: An autoimmune condition leading to thick, scaly, red plaques, often on the elbows, knees, or scalp. The appearance of well-defined, erythematous plaques can suggest psoriasis.
  • Contact Dermatitis: A type of skin inflammation caused by contact with irritants or allergens, leading to red, itchy, and sometimes blistered skin. This diagnosis is considered if the skin lesions are localized to areas that could have come into contact with an offending agent.
  • Acne: A skin condition that occurs when your hair follicles become plugged with oil and dead skin cells, leading to pimples, blackheads, or whiteheads, mainly on the face. If the lesions are predominantly on the face and include comedones, acne is a likely diagnosis.

• Do Not Miss Diagnoses

  • Skin Cancer (Melanoma, Basal Cell Carcinoma, Squamous Cell Carcinoma): Although less common, these conditions are critical to identify early due to their potential for serious morbidity and mortality. Any new or changing skin lesion, especially those that are asymmetric, have irregular borders, color variation, diameter larger than 6mm, or are evolving, should raise suspicion for skin cancer.
  • Infectious Diseases (e.g., Cellulitis, Abscess, Impetigo): These conditions can present with skin lesions and require prompt treatment to prevent spread and complications. Signs of infection such as redness, warmth, swelling, and pus should not be overlooked.
  • Autoimmune Disorders (e.g., Lupus, Dermatomyositis): These conditions can manifest with skin lesions among other systemic symptoms. A thorough review of systems and examination is necessary to consider these diagnoses.

• Rare Diagnoses

  • Sarcoidosis: A condition in which inflammatory cells clump together in various organs, including the skin, leading to lesions or rashes. It's considered rare but should be thought of in cases where skin lesions are accompanied by systemic symptoms or findings suggestive of multi-organ involvement.
  • Cutaneous T-Cell Lymphoma (Mycosis Fungoides): A rare type of cancer that initially presents in the skin, causing lesions that can mimic more common skin conditions. It's a diagnosis to consider in cases where skin lesions are persistent and unresponsive to typical treatments.