A case of diabetic ketoacidosis with prurigo pigmentosa as a dermadrome

Hyperketonemia is a risk factor for prurigo pigmentosa; therefore, diabetic ketosis and ketoacidosis as background diseases are more frequent in prurigo pigmentosa. However, it is underrecognized by clinicians and easily missed. Herein, we present a case of diabetic ketoacidosis in which prurigo pigmentosa was recognized as a dermadrome. A 37-year-old woman with no medical history presented with thirst, polydipsia, and polyuria approximately 1 month prior to transport. and a pruritic skin rash on both shoulders 1 week later. After no diagnosis by a local dermatologist, the patient was diagnosed with diabetic ketoacidosis, and insulin therapy was initiated at our hospital. Based on the patient’s history, post-hospitalization course, and pathological findings, the pruritic skin rash was diagnosed as prurigo pigmentosa. The clinical course suggested that prurigo pigmentosa is a dermadrome of diabetic ketosis and ketoacidosis. The medical clinicians’ awareness of its relevance is crucial for designing therapeutic interventions for diabetic ketosis and ketoacidosis.