Key distinguishing features of the most common diagnoses
|Androgenic||Seborrhoeic Dermatitis||Alopecia Areata||Allergic Dermatitis||Tinea Capitis|
|Abnormal Skin on Body||No||Possible||No||Possible||Possible|
|Exclamation Mark Hairs||No||No||Yes||No||No|
|Patchy Hair Thinning||Yes (M) No (F)||Yes||Yes||Yes||Yes|
|Scaling and Weeping||No||Yes||No||Possible||Yes|
Possible:Wood’s light test, hair and scales for mycology.
Small Print:FBC, ESR/CRP, U&E, TFT, FSH/LH, prolactin, autoimmune tests, syphilis serology.
- Microsporum infections will fluoresce green under a Wood’s (UV) light.
- Send scrapings and hair for mycology if the scalp looks abnormal.
- FBC, ESR/CRP and autoimmune tests may help identify autoimmune causes, e.g. SLE.
- Syphilis serology: Old-fashioned, but syphilis is on the increase.
- U&E, TFT, FSH/LH, prolactin will effectively screen for endocrinopathy.
- Alopecia areata is occasionally associated with other autoimmune diseases. Further assessment is sensible, even at a later consultation.
- Remember that in telogen effluvium, the traumatic event – such as a significant illness or childbirth – will have taken place about 4 months before the onset of hair loss, so the connection is unlikely to be made by the patient.
- The patient invariably fears total hair loss – ensure that this is broached and that a realistic prognosis is given.
- Lymphadenopathy in association with alopecia may suggest an infective process – consider bacterial folliculitis.
- Alopecia areata has a particularly poor prognosis if there are several patches, there is loss of eyebrows or eyelashes, or if it begins in childhood.
- Scarring alopecia should prompt the clinician to look for general signs of lupus erythematosus.
- Trichotillomania in children is usually simply due to habit; in adults, though, it is more often a sign of significant psychological disturbance.