Poikiloderma with neutropenia: An alternate presentation with dyspigmentation and novel USB1 mutation.

Two siblings presented with sun sensitivity and progressive dyspigmentation. A diagnosis of xeroderma pigmentosum was initially favored due to XPC mutations, although variants were not clearly diagnostic. However, new moderate neutropenia and homozygous suspected pathogenic variants in USB1 led to diagnosis of poikiloderma with neutropenia. This case highlights the importance of reevaluation of diagnosis due to significant phenotypic overlap in congenital disorders of photosensitivity with poikiloderma or dyspigmentation.