Derm Dx: Whitening and crumbling of fingernails

An 11-year-old boy is brought to the office by his mother following the occurrence of a slight fever and mouth irritation accompanied by blisters on his hands and feet that developed approximately 3 weeks prior to this visit. His mother is also concerned about recent nail changes affecting several fingers. Examination reveals distal whitening and crumbling of 3 fingernails.