Postautologous Hematopoietic Stem Cell Transplantation Disseminated Hypopigmented Keratosis.

Disseminated hypopigmented keratosis is a rare distinct clinical entity. This report describes the case of a 19-year-old male patient who developed disseminated hypopigmented keratosis 2 months after autologous hematopoietic stem cell transplantation for pineal choriocarcinoma. The patient displayed numerous tiny whitish or depigmented macules and papules on the chest, back, posterior neck, shoulders, arms, and thighs, closely resembling lichen nitidus. Microscopically, the lesion was orthokeratotic, acanthotic, and flat-bottomed without cytological atypia. Dermal inflammation was minimal. Fontana-Masson, Melan-A, and sex-determining region Y-box transcription factor 10 staining revealed a significant decrease in both basal melanin content and the number of melanocytes. The patient was initially administered a topical agent comprising hydrocortisone and urea, which exhibited minimal improvement. This case report suggests that disseminated hypopigmented keratosis may be a rare cutaneous manifestation of autologous hematopoietic stem cell transplantation. Additional research is necessary to gain a more comprehensive understanding of the pathogenesis and the clinical course of this disease.