A 15-year-old girl has a 1-month history of urinary frequency without dysuria and recent onset of an itchy rash beneath both breasts. She has been gaining weight over the past year and regularly complains of fatigue. She is afebrile, with a weight greater than the 99th percentile and has an erythematous, macular rash beneath both breasts characterized by satellite lesions. Urinalysis is significant for 2+ glucosuria but no pyuria. Which of the following is the most likely diagnosis? (A) Diabetes mellitus (B) Fanconisyndrome (C) Human immunodeficiency virus (D) Occult malignancy (E) Severecombinedimmunodeficiency(SCID)

 The most likely diagnosis for the 15-year-old girl described is (A) Diabetes mellitus. The clinical picture provided suggests that she has symptoms consistent with uncontrolled diabetes mellitus. The urinary frequency without pain (dysuria) and the presence of glucose in the urine (glucosuria) are indicative of high blood sugar levels that result in sugar spillover into the urine. The weight gain and fatigue might be related to insulin resistance, which is common in type 2 diabetes, especially in the context of obesity. The presence of an erythematous, macular rash with satellite lesions beneath both breasts suggests a candidal skin infection, which is common in individuals with diabetes due to the high sugar environment which allows yeast to thrive. A lack of fever (afebrile) does not suggest an active and systemic bacterial infection. The other conditions listed (Fanconi syndrome, HIV, occult malignancy, SCID) are less consistent with the described symptoms and laboratory findings.