A 49-Year-Old Woman Notes the Onset of a Painful Reddish-Blue Discoloration Under One Fingernail

A 49-year-old African-American woman noted the gradual onset of reddish-blue discoloration under one fingernail. There was both spontaneous pain and exquisite tenderness to palpation. Discomfort was both elicited and worsened when the patient washed her hands with cold water or touched cans or packages from the refrigerator or freezer. The patient was ostensibly in good health, took no medications, and was a nonsmoker and nondrinker.