Figure tuab_01a_n.jpg and tuab_01b_n.jpg: Two toddlers with a visible and palpable abdominal mass. Figure tuab_01a_n.jpg: 4.5-year-old girl with a protruding belly. In contrast to the slender left flank the abdominal level of the right flank and of the middle of the belly is protruding with visible masses around the navel. The diagnosis is a neoplastic abdominal tumor which starts from the right flank and passes over the midline to the left side. Notice the marked limits of the palpable tumor. The most probable diagnosis is a nephroblastoma, which was confirmed by additional examinations. Figure tuab_01b_n.jpg: 3.3-year-old boy with a large belly. On the left side of the navel there is tympanitic sound on percussion, while on the right side a firm mass is recognizable corresponding to the drawing which reaches the midline. In this case a Wilms' tumor also was the cause of the clinically seizable abdominal tumor.