We report six patients with a previously undescribed but characteristic pustular dermatosis confined to the scalp. All the patients were elderly women who developed chronic, extensive, pustular, crusted and occasionally eroded lesions of the scalp which produced scarring alopecia. Investigations were essentially negative and skin biopsies showed only non-specific changes of atrophy and chronic inflammation, sometimes with increased plasma cells in the infiltrate. The condition did not respond to antibiotics, but was suppressed by potent topical steroids.

Eleven of 12 cases with erosive pustular dermatosis ofthe scalp gave a history of antecedent physical or infective trauma. We propose that this clinical disorder may be a non-specific inflammatory response to injury of ageing and sun-damaged scalps.Erosive pustular dermatosis ofthe scalp was described by Pye, Peachey and Burton in 1979.' They reported six cases, all elderly women, who presented with persistent erosions, pustulation and scarring confined to thc scalp. Histology showed a spectrum of changes including epidermal erosions, follicular destruction and chronic inflammatory infiltrates rich in plasma cells although none of these features were diagnostic in themselves. Response to antibiotics was poor, hut the condition was suppressed by potent topical steroids, suggesting an inflammatory rather than an infective aetiology. Since the original report we have collected a further 12 cases from clinics in Avon, Somerset and the Midlands and wish to draw attention to the high incidence of antecedent loca! trauma, which we feel is important in the pathogenesis of the disorder. PatientsSeven ofthe patients were men, five were women. Their mean age at presentation was 75 years, range 59-90. All presented with well defined areas of persistent crusting and adherent keratinous debris in the scalp, removal of which revealed moist superficial erosions and, often, pus.Discrete pustules and open erosions were sometimes evident. Scarring and loss of hair from the affected scalp were common. Six ofthe men and one ofthe women had longstanding physiological baldness prior to the onset of Ccorrespondence: I3r C^.

Summary and conclusions Twenty-five patients taking part in a controlled trial to compare azathioprine plus prednisone with prednisone alone in the treatment of pemphigoid were followed up for three years. Results showed that the addition of azathioprine 2 5 mg/kg body weight daily reduced the total maintenance dose of prednisone needed by about 45%, with no increase in serious side effects or mortality.The suggestion that azathioprine might increase the risk of disseminated malignancy in elderly patients was not supported.We conclude that in future trials the combination of azathioprine with prednisone should be used as the standard treatment for comparison.

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