A 2½-year-old girl presented with bilateral breast development first noticed 5 days previously. Each breast was hypertrophied. One day later, she returned with abdominal pain, fatigue, and irritability. She had diffuse abdominal and rectal tenderness that was greater on the right side. An abdominal roentgenogram revealed the absence of bowel gas in the right lower quadrant. An abdominal ultrasound study showed a 6×10-cm multicystic mass in the lower abdomen (Fig 1).
On examination, she was pale and uncomfortable. Vital signs were as follows: heart rate, 170 beats per minute; blood pressure, 100/45 mm Hg; and respiratory rate, 45 breaths per minute. The abdomen was tense, with absent bowel sounds in the right lower quadrant. There were no palpable masses, although the examination was suboptimal because of distention and guarding. Breast examination revealed 2-cm hypertrophy without increased areolar pigmentation. She appeared to be a normal prepubertal female. Admission laboratory data were