Differential Diagnosis for Itchy Scalp
The patient presents with a history of dandruff, severe pruritis leading to scalp bleeding and abrasions, and hair loss in scratched areas. Here's a categorized differential diagnosis:
- Single Most Likely Diagnosis
- Severe dandruff or psoriasis: The patient's history of dandruff and the current presentation of severe pruritis, scalp bleeding, and hair loss are consistent with an exacerbation of psoriasis or severe dandruff, especially given the lack of medication.
- Other Likely Diagnoses
- Atopic dermatitis (eczema): Could be a contributing factor or the primary cause, given the severe pruritis and scratching leading to abrasions.
- Seborrheic dermatitis: An inflammatory skin condition that can cause a red, itchy, and flaky scalp, which aligns with the patient's symptoms and history.
- Fungal infections (e.g., ringworm of the scalp): Could cause itching, hair loss, and potentially bleeding if scratched severely.
- Do Not Miss Diagnoses
- Scalp lymphoma or cutaneous T-cell lymphoma: Although rare, these conditions can present with severe itching, skin lesions, and hair loss. Missing these diagnoses could be fatal.
- Bullous pemphigoid: An autoimmune skin disease that can cause severe itching and blistering. It's less common but critical not to miss due to its potential for significant morbidity.
- Rare Diagnoses
- Kerion: A rare but serious form of tinea capitis (fungal infection of the scalp) that can cause severe inflammation, itching, and hair loss.
- Alopecia areata: An autoimmune condition leading to hair loss, which could be exacerbated by or contribute to the patient's scratching and subsequent symptoms.
- Neurological causes of itching (e.g., neuropathic pruritus): Rare conditions where neurological issues lead to severe itching without a clear dermatological cause.