Differential Diagnosis for Annular Lesion on Posterior Shoulder
- Single most likely diagnosis
- Tinea corporis (ringworm): This is a common fungal infection in children, characterized by a well-circumscribed, annular lesion with a rough, scaly border and a clear center. The lesion's appearance and location on the posterior shoulder, without symptoms, make this diagnosis likely.
- Other Likely diagnoses
- Nummular eczema: This condition presents with coin-shaped, well-circumscribed lesions that can be rough and scaly. Although it's more common in adults, it can occur in children, especially if there's a history of atopic dermatitis.
- Granuloma annulare: This is a benign skin condition that can appear as a ring-shaped lesion with a rough texture. It's more common in children and young adults, and its cause is unknown.
- Seborrheic keratosis: Although more common in adults, seborrheic keratoses can occur in children. They appear as well-circumscribed, rough lesions that can be darkened, but they tend to be smaller than 2 inches.
- Do Not Miss diagnoses
- Malignant melanoma: Although rare in children, it's crucial to consider melanoma in the differential diagnosis of any new or changing skin lesion, especially if it's pigmented and has an irregular border. Early detection is vital for treatment and prognosis.
- Inflammatory or infectious conditions (e.g., erythema migrans, the rash of Lyme disease): These conditions can present with annular lesions and may have significant consequences if left untreated.
- Rare diagnoses
- Sarcoidosis: This is a systemic disease that can cause skin lesions, including annular ones. However, it's rare in children and would typically be accompanied by other systemic symptoms.
- Annular lichen planus: This is a rare variant of lichen planus, which can present with annular lesions. However, it's more common in adults and would typically be accompanied by other symptoms like pruritus.