Long-term clearance of linear porokeratosis with tacrolimus, 0.1%, ointment.

Report of a Case A woman in her 40s with no significant medical history was referred for evaluationof apainful dermatitis onher left arm.Approximately 1 yearearlier, apainful, pruritic, erythematouspapulehaddevelopedonher leftarm,whichsubsequentlyspread intoa lineararray of papules extending fromher left wrist up her arm to her neck, associatedwithpruritus,paresthesias, andpain;3to 10-mmerythematous papules with overlying scales were arranged in a linear pattern extending up the ventral part of her arm, across her shoulder to the left side of her neck and chest (Figure 1). Several lesions exhibited an outer hyperkeratotic rim. She had similarly shaped areas of hyperpigmentation without overlying epidermal change on her left arm and on the left side of her chest and neck. A skin biopsy sample revealed a vertical columnof parakeratosis within the stratum corneum, an absent granular layer underlying the column, and a focal lymphohistiocytic infiltrate underlying theepidermal change.Theclinical andhistopathologic featuresconfirmed a diagnosis of linear porokeratosis. The patient had been treatedwithbetamethasonedipropionate,0.05%,ointment forseveralmonthswithminimal improvement;oral acitretin treatmentwas subsequently started at 25mg/d. After 3months of acitretin treatment, she had no improvement of the lesions on her arm but had adverse effects, including scaling of her palms and soles and dryness of her lips and face. We continued daily treatment with betamethasone dipropionate, 0.05%, ointment and added tacrolimus, 0.1%, ointment, administered twice daily, to the patient’s treatment regimen. Oral acitretin treatment was discontinued because it had caused adverse effects with no skin improvement. With the combination of betamethasoneandtacrolimus, theskin lesions improvedrapidlyanddramatically.At the2-month follow-upexamination, thepatienthadhyperpigmentedmaculesandpatches ina linearpatternuptheventral side of her left arm and across the shoulder to her neck on the left side, consistentwithpostinflammatoryhyperpigmentation. The inflammationhadcompletely cleared. In addition to improvedskin lesions, the patient reported complete resolution of associated pain, pruritus, and paresthesia. The patient was followed up at 3to 6-month intervals for 21⁄2 years, during which her skin showed continued improvement. Tacrolimus treatment was tapered down to once-daily administration to areas of postinflammatory hyperpigmentation and anynew lesions, with betamethasone used only on new lesions. At 21⁄2-year follow-up, the daily tacrolimus treatment was discontinued. At examination, the patient’s skin was essentially back to baseline, with onlya fewvery faint reticulatedpale-brownmacules (Figure2), thus demonstrating the long-termefficacyof treatmentwith topical betamethasone and tacrolimus.