Differential Diagnosis for Itchy Chest, Underarms, and Face
Single Most Likely Diagnosis
- Atopic Dermatitis (Eczema): This condition is characterized by itchy, inflamed skin and is common in areas such as the chest, underarms, and around the face. The distribution and symptoms described fit well with atopic dermatitis, especially if the patient has a history of allergies or asthma.
Other Likely Diagnoses
- Contact Dermatitis: This could be due to an allergic reaction or irritant exposure, leading to itchy skin in the affected areas. Common culprits include soaps, detergents, or new cosmetics.
- Seborrheic Dermatitis: This condition causes scaly patches, red skin, and stubborn dandruff, often affecting oily areas of the body like the face and, less commonly, the chest and underarms.
- Dry Skin (Xerosis): Especially during dry weather or with excessive bathing, dry skin can become itchy and affect various parts of the body, including the chest, underarms, and face.
Do Not Miss Diagnoses
- Scabies: A parasitic infection caused by the mite Sarcoptes scabiei, leading to intense itching, especially at night, and can affect any part of the body, including the face in severe cases or in immunocompromised patients.
- Bullous Pemphigoid: An autoimmune disease that can cause large blisters and itchy skin. Although less common, it's critical to diagnose due to its potential severity and need for specific treatment.
- Cutaneous T-Cell Lymphoma (Mycosis Fungoides): A rare type of skin cancer that can present with itchy skin lesions, patches, or plaques, often on the chest, back, and face.
Rare Diagnoses
- Pityriasis Rosea: Characterized by a rash that starts with a single patch (herald patch) followed by an eruption of smaller patches, typically on the trunk, but can occasionally involve the face and underarms.
- Dermatitis Herpetiformis: An autoimmune blistering disorder associated with celiac disease, characterized by intensely itchy, blistering skin, usually on the elbows, knees, and buttocks, but can occasionally affect other areas.
- Erythroderma (Exfoliative Dermatitis): A condition where there is widespread scaling, redness, and peeling of the skin, often accompanied by itching, which can be life-threatening if not properly managed.