THERAPEUTIC HOTLINE: LETTERS Unsuccessful treatment of progressive macular hypomelanosis with oral isotretinoin Dear Editor, Progressive macular hypomelanosis (PMH) is a common disorder charac- terized by symmetrically distributed ill-defined, hypopigmented macules mainly on the trunk (Relyveld, Menke, & Westerhof, 2007) . Although the underlying etiology of this condition is unclear, there is circumstantial evidence that links Propionibacterium acnes to the condition (Cavalcanti et al., 2011; Petersen, Scholz, Jensen, Br€ uggemann, & Lomholt, 2017). Different treatment modalities for PMH have been reported in literature including phototherapy, topical or systemic antimicrobial agents and top- ical corticosteroids and retinoids (Relyveld et al. 2007; Kim et al., 2012). In 2012, Kim et al. described a patient with PMH treated with low-dose isotretinoin for 1 month, inducing complete remission (Kim, Lee, Lee, & Yoon, 2012). This case report describes a patient with PMH who was unsuccessfully treated with oral isotretinoin. A 22-year-old male with Fitzpatrick skin type III presented with widespread hypopigmented macules of a 5-year duration. He had been diagnosed as having tinea versicolor and was treated with multiple courses of topical and systemic antifungal agents without improvement and with progression of his lesions. Dermatological examination revealed symmetrically distributed, nonscaly, nonatrophic, hypopigmented macules, 2–15 mm in diameter, distributed on the trunk and the upper limbs, which were more pre- dominant on proximal and extensor aspects (Figure 1). An excisional biopsy from the lesion showed normal epidermis. No significant dermal inflammation or melanophages were seen. A PAS stain yielded negative results for fungal and yeast organisms. A diagno- sis of PMH was made based on the clinical and histological findings. A 2-month treatment with oral minocycline and 0.05% tretinoin cream proved ineffective. The long journey from his residence to the Phototherapy Center made phototherapy not feasible for our patient. Oral isotretinoin (0.4 mg/kg/day) was initiated, without improvement at a 3-month fol- low-up (Figure 2). At the time of this report, 2 years after the initial pre- sentation, the skin involvement remained unchanged. FIGURE 1 1 Before treatment. Symmetrically distributed ill-defined, nonscaly, and hypopigmented macules FIGURE 2 After 3 months of treatment with isotretinoin, the skin lesions remained unchanged. Note the improvement of mild acne on the upper back Dermatologic Therapy. 2017;e12514. https://doi.org/10.1111/dth.12514 wileyonlinelibrary.com/journal/dth V C 2017 Wiley Periodicals, Inc. | 1 of 2 Received: 3 April 2017 | Revised: 12 May 2017 | Accepted: 18 May 2017 DOI: 10.1111/dth.12514