Differential Diagnosis for Nummular Eczema
- Single most likely diagnosis
- Atopic dermatitis: This is often considered due to the similar appearance and symptoms of nummular eczema, which can sometimes be a manifestation of atopic dermatitis. The presence of a personal or family history of atopy (asthma, allergies) can support this diagnosis.
- Other Likely diagnoses
- Contact dermatitis: Both irritant and allergic contact dermatitis can present with coin-shaped lesions similar to nummular eczema, especially if the causative agent is something that comes into contact with the skin in a localized, circular pattern.
- Psoriasis: Plaque psoriasis can sometimes present with circular lesions, although they typically have a thicker, more scaly appearance than nummular eczema.
- Seborrheic dermatitis: While seborrheic dermatitis more commonly affects the scalp, face, and central chest, it can occasionally present with lesions on the extremities that might be confused with nummular eczema.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Cutaneous T-cell lymphoma (Mycosis fungoides): This rare condition can mimic many dermatoses, including nummular eczema, especially in its early stages. It's crucial to consider this diagnosis, especially if the lesions are persistent and not responding to typical treatments.
- Infectious diseases (e.g., ringworm, erythema migrans): Certain infectious diseases can present with circular lesions. For example, tinea corporis (ringworm) can cause circular, itchy lesions, and erythema migrans (the rash of Lyme disease) often appears as a circular, expanding lesion.
- Rare diagnoses
- Granuloma annulare: This condition can present with circular lesions, although they are typically more papular and less eczematous than nummular eczema.
- Necrobiosis lipoidica: A rare condition that can cause circular, necrotic lesions, often on the lower legs. It's associated with diabetes mellitus and can be mistaken for nummular eczema, although it typically has a more distinctive appearance.