Open Access
Feature Article

Scalp pruritus – scratching for answers

Open Access
Feature Article

Scalp pruritus – scratching for answers

SARAH ROSE ADAMSON, RACHAEL DAVENPORT, ALVIN H. CHONG, Peter Foley

Figures

© nobeastsofierce/ shutterstock.com
© nobeastsofierce/ shutterstock.com
Dr Adamson is a Dermatology Research and Education Fellow at the Skin Health Institute, Melbourne; and a Dermatology Fellow at The Royal Women’s Hospital, Melbourne. Dr Davenport is a Dermatology Registrar at St Vincent’s Hospital, Melbourne. Adjunct Associate Professor Chong is a Specialist Dermatologist at St Vincent’s Hospital, Melbourne; Head of the Transplant Dermatology Clinic and Producer of Spot Diagnosis Podcast at Skin Health Institute, Melbourne. Associate Professor Foley is the Director of Research at the Skin Health Institute, Melbourne; Head of Dermatology Research at St Vincent’s Hospital, Melbourne; and Associate Professor of Dermatology at The University of Melbourne, Melbourne, Vic.

Scalp pruritus often occurs in the context of generalised whole-body pruritus. The medication history may reveal a pharmacological cause. Common triggers include opioids, NSAIDs, antihypertensive drugs, especially thiazide diuretics, lipid-lowering drugs, such as statins, and antibiotics. In rare cases, generalised pruritus is associated with an underlying disease process, including malignancy. In patients with lymphoma, pruritus can be associated with systemic symptoms such as night sweats and weight loss.

Investigations for patients with chronic pruritus on noninflamed skin who do not respond to therapy depend on the clinical findings. Basic investigations can include a full blood count, measurement of electrolytes, thyroid function tests, iron studies and chest radiography.

In patients with unexplained scalp pruritus, empirical treatment may be helpful. Tar-based shampoos are useful as they have antipruritic properties. If itch persists then systemic therapies may be used, including antihistamines and antidepressants such as doxepin and selective serotonin reuptake inhibitors.

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Is there a role for punch biopsy in the work-up for scalp pruritus?

Biopsies can be very helpful in reaching a diagnosis; however, scalp biopsies are ideally performed in a controlled setting (e.g. by a dermatologist) because of the associated risk of bleeding and the need for dermatopathologist expertise in interpreting the results. Biopsies can be useful in differentiating conditions such as psoriasis from eczema, and for diagnosing lichen simplex chronicus, lichen planopilaris and, occasionally, folliculitis. A scalp biopsy is useful for diagnosing dermatitis herpetiformis; however, ideally the biopsy would be taken from a more typical body site other than the scalp.

When should patients be referred?

Referral to a dermatologist is recommended in cases of persistent diagnostic uncertainty and disease that does not respond to treatment. Early dermatology referral is essential for patients with dermatitis herpetiformis, lichen planopilaris and other types of scarring alopecia. 

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Conclusion

Scalp pruritus is a common symptom that can be associated with a range of dermatological conditions. It is important to identify distinguishing features in the patient’s history and examination results to make an accurate diagnosis. Sometimes, a therapeutic trial is needed before the diagnosis is known.     MT

 

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COMPETING INTERESTS: Dr Adamson, Dr Davenport and Associate Professor Chong: None. Associate Professor Foley has served as a Consultant, Investigator, Speaker or Advisor for, or received research or travel grants from  AbbVie, Amgen, Arcutis, Aslan, AstraZeneca, Boehringer Ingelheim, Bristol Myers Squibb, Celtaxsys, Dermira, Eli Lilly and Company, Evelo, Galderma, GenesisCare, Janssen, Kymab,  LEO Pharma, MedImmune, Novartis, Pfizer, Regeneron, Reistone Biopharma, Sanofi Genzyme, Sun Pharma, Teva and UCB Pharma.