Acne necrotica is a pustular eruption of the scalp in older patients, usually men. Some consider this a variant of rosacea.
Scattered pustules that rapidly break or are excoriated form crusts in the scalp. Patients often complain of significant itch. Some patients may have typical pimples on the face as well, ala rosacea.
No treatment is curative. A potent topical steroid (e.g., betamethasone) may be applied BID. Use of a daily medicated shampoo may help. If these measures fail, or more aggressive therapy is desired, oral doxycycline (e.g., 100 mg BID) or minocycline (e.g., 100 mg BID) may be given. Sometimes amoxicillin 500 mg BID is effective when the tetracyclines are not.
Rarely in resistant cases, isotretinoin may be given.
One patient of mine did well using chlorhexidine topical (e.g., Hibiclens) to clean the scalp daily in the shower. Another kept his pustules away using tar shampoo 2/week.