Clinical History.—A Negro boy weighing 3 kg (6 lb 10½ oz) was the product of an uncomplicated term pregnancy and delivery of an 18-year-old primigravida. On routine nursery examination, a large abdominal mass occupying the entire left upper quadrant was palpated. The mass was firm and noncystic with irregular but smooth borders. Results of the remainder of the physical examination were normal.
Initial complete blood cell count and results of urinalysis were normal. After roentgenograms of the abdomen, inferior vena cavagram, and an excretory urogram were obtained, the patient underwent exploratory laparotomy (Fig 1, 2, and 3).
Denouement and Discussion
Fetal Mesenchymal Hamartoma of the Kidney
The erect roentgenogram of the abdomen (Fig 1) shows a mass occupying the left flank with no calcifications. Inferior vena cavagram reveals no displacement or obstruction of the vena cava (Fig 2). The excretory urogram, however, shows blunting and distortion of the left