ABSTRACT
A female patient aged 3 years and 1 month developed poikilodermatous patches on the right forearm at the age of 6 months, which spread to bilateral cheeks, buttocks and limbs at the age of 1 year and 4 months. Skin examination showed multiple brown and off-white poikilodermatous patches on the bilateral cheeks, buttocks and limbs, which were intermingled with normal skin and did not merge with each other. The trunk and oral mucosa were not involved. The fifth toenail of the right foot was thickened. Blood routine examination showed that the neutrophil count fluctuated between 1.70 × 10 9/L and 9.32 × 10 9/L. Histopathological examination of the brown patches on the left upper limb showed hyperpigmentation in the basal layer of the epidermis, and a few melanophages around the dermal vessels. Next-generation sequencing of peripheral blood genomic DNA revealed two compound heterozygous mutations c.798A>G in exon 7 and c.479delT in exon 3 of the USB1 gene in the child, which were inherited from her father and mother respectively. Neither of the two mutations was identified in 100 unrelated healthy controls. The patient was diagnosed with poikiloderma with neutropenia.