Itchy Scalp
This might appear a mundane symptom to the GP, but it can cause the patient significant distress. It’s usually a welcome presentation, as it’s perceived as a quickie – one of those problems in which a brief examination can be performed at the same time as an equally brief history. This approach generally pays dividends, but the problem can sometimes be more complicated than it might at first appear.
Differential diagnosis
Common Diagnoses
- Head Lice
- Seborrhoeic Eczema
- Psoriasis
- Lichen Simplex
- Impetigo (May be Underlying Head Lice or Eczema)
Occasional Diagnoses
- Allergic/Contact Eczema
- Other Fungal Infections
Rare Diagnoses
- Stress/Depression
- Viral Infection (e.g. Chickenpox – a Common Problem but only Rarely Presents with Scalp Itch)
Ready reckoner
Key distinguishing features of the most common diagnoses
| Head Lice | Seborrhoeic Eczema | Psoriasis | Lichen Simplex | Impetigo | |
|---|---|---|---|---|---|
| Scaly Scalp | No | Yes | Yes | Possible | No |
| Pustular Lesions | Possible | No | No | No | Yes |
| Skin Lesions Elsewhere | No | Possible | Possible | Possible | Possible |
| Visible Egg Cases | Yes | No | No | No | No |
| Chronic Problem | No | Possible | Yes | Possible | No |
Possible investigations
- It is highly unlikely that any investigations will be required at all. Confirmation of a fungal infection may be obtained via fluorescence under a Wood’s light or by microscopy and culture of scalp and hair samples.
Top Tips
- Whatever the actual diagnosis, scratching will perpetuate or complicate the problem and so should be discouraged.
- Consider examining the skin and nails, as these may provide useful additional clues.
- The diagnosis in a child is very likely to be head lice; the list of differentials increases the older the patient.
Red Flags
- Scalp impetigo in a child – particularly if it relapses rapidly – suggests an underlying problem such as head lice or eczema. This needs treating too, or the symptom will persist.
- In an otherwise puzzling case, consider psychological causes – stress and depression can sometimes present with scalp itching.