Differential Diagnosis
- Single most likely diagnosis
- Atopic dermatitis (eczema): The presence of bumps around the hairline, combined with a history of asthma, suggests an allergic or atopic etiology. The denial of new soap or shampoo reduces the likelihood of an irritant contact dermatitis.
- Other Likely diagnoses
- Contact dermatitis: Despite the denial of new soap or shampoo, it's still possible that the patient has developed an allergic contact dermatitis to a product or substance. Other possibilities include seborrheic dermatitis, given the location around the hairline.
- Tinea capitis (ringworm of the scalp): This fungal infection can cause bumps, scaling, and hair loss, and is more common in children. The non-productive cough could be unrelated or a sign of an allergic reaction.
- Allergic reaction: An allergic reaction to an insect bite, food, or environmental allergen could cause bumps around the hairline and a non-productive cough, especially if the patient has a history of asthma.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Meningitis: Although the presentation is not typical, meningitis can cause a rash and respiratory symptoms, including cough. It's essential to consider this diagnosis, especially if the patient has a fever, headache, or stiff neck.
- Tuberculosis (TB): TB can cause a chronic cough and skin lesions, although this would be an unusual presentation. It's crucial to consider TB in patients with a history of exposure or immunocompromised status.
- Rare diagnoses
- Sarcoidosis: This autoimmune disease can cause skin lesions, respiratory symptoms, and other systemic manifestations. However, it's relatively rare in children and would require further evaluation.
- Histoplasmosis: This fungal infection can cause skin lesions, respiratory symptoms, and other systemic manifestations, but it's relatively rare and usually associated with specific geographic or environmental exposures.