Two shave biopsies were taken, 1 in the center of a previous SCC site with hyperkeratosis, the other in a site not previously affected by SCC but with the physical features of a pustule. Biopsy results from both sites were consistent with erosive pustular dermatosis, an unusual inflammatory disorder that mimics SCC.
Erosive pustular dermatosis of the scalp is an uncommon dermatitis that usually affects older women but may appear in men and women of all ages. It can mimic many other conditions that can affect the scalp, including seborrheic dermatitis, psoriasis, actinic keratosis, and SCC.
The exact causative mechanism is not understood, and cases may develop spontaneously. Rough papules, pustules, crusts, and ulcers develop and (apart from the pustules) share many features of actinic keratoses, SCCs, and field cancerization. The presence of pustules helps point to the diagnosis.
Triggers include previous surgery or physical trauma, burns, skin or hair grafts, and treatment of actinic keratoses with imiquimod, 5-fluourouracil, or photodynamic therapy. Some autoimmune diseases (including Hashimoto thyroiditis, autoimmune hepatitis, and rheumatoid arthritis) have been linked to disease occurrence and severity.1
Treatment includes potent or super-potent topical steroids such as clobetasol 0.05% ointment. Topical tacrolimus 0.1% ointment and calcipotriene 0.005% cream have been reported as steroid alternatives. Paradoxically, photodynamic therapy, while associated with triggering disease, has also been used therapeutically. Systemic immunomodulators such as cyclosporine 3 mg/kg/d or prednisone 0.5 to 1 mg/kg/d may be needed in severe cases. Antibiotics including topical dapsone 5% gel, systemic dapsone from 50 mg bid to tid, and doxycycline have been helpful due, in part, to their immunomodulatory effects.1,2
This patient was told to apply topical triamcinolone 0.1% ointment around and over ulcers and pustules and to take doxycycline 100 mg twice daily. The patient cleared well after 6 weeks. He continued to apply topical triamcinolone every few days as maintenance therapy.
He had some mild recurrence after discontinuing all topical and oral therapy, so he currently is being maintained on topical clobetasol 0.05% ointment every other day. He comes in for follow-up appointments every 3 months to monitor for control of the erosive pustular dermatosis of the scalp and for skin cancer surveillance.
Photos and text for Photo Rounds Friday courtesy of Jonathan Karnes, MD (copyright retained). Dr. Karnes is the medical director of MDFMR Dermatology Services, Augusta, ME