Giant hydronephrosis mimicking progressive malignancy

Abstract

Background: Cases of giant hydronephroses are rare and usually contain no more than 1-2 litres of fluid in the collecting system. We report a remarkable case of giant hydronephrosis mimicking a progressive malignant abdominal tumour.

Case presentation: A 78-year-old cachectic woman presented with an enormous abdominal tumour, which, according to the patient, had slowly increased in diameter. Medical history was unremarkable except for a hysterectomy >30 years before. A CT scan revealed a giant cystic tumour filling almost the entire abdominal cavity. It was analysed by two independent radiologists who suspected a tumour originating from the right kidney and additionally a cystic ovarian neoplasm. Subsequently, a diagnostic and therapeutic laparotomy was performed: the tumour presented as a cystic, 35 x 30 x 25 cm expansive structure adhesive to adjacent organs without definite signs of invasive growth. The right renal hilar vessels could finally be identified at its basis. After extirpation another tumourous structure emerged in the pelvis originating from the genital organs and was also resected. The histopathological examination revealed a >15 kg hydronephrotic right kidney, lacking hardly any residual renal cortex parenchyma. The second specimen was identified as an ovary with regressive changes and a large partially calcified cyst. There was no evidence of malignant growth.

Conclusion: Although both clinical symptoms and the enormous size of the tumour indicated malignant growth, it turned out to be a giant hydronephrosis. Presumably, a chronic obstruction of the distal ureter had caused this extraordinary hydronephrosis. As demonstrated in our case, an accurate diagnosis of giant hydronephrosis remains challenging due to the atrophy of the renal parenchyma associated with chronic obstruction. Therefore, any abdominal cystic mass even in the absence of other evident pathologies should include the differential diagnosis of a possible hydronephrosis. Diagnostic accuracy might be increased by a combination of endourological techniques such as retrograde pyelography and modern imaging modalities.

Figure 1

Intravenous Urography. Intravenous urography showed good excretion of contrast by the left kidney and ureter, however, there was no contrast medium excretion on the right side. In addition, an oval structure with peripheral calcification appeared in projection to the pelvis, which compressed the urinary bladder from cranial.

Figure 2

Abdominal CT scan. CT scan of the giant abdominal tumour filling almost the entire abdominal cavity displacing the small intestine, colon, pancreas, spleen and the left kidney.

Figure 3

Cranial pelvic CT scan. CT scan of the second structure, which was localised in the pelvis and diagnosed to be a cystic ovarian neoplasm: cranial scan.

Figure 4

Caudal pelvic CT scan. CT scan of the second structure, which was localised in the pelvis and diagnosed to be a cystic ovarian neoplasm: caudal scan.

Figure 5

Operative situs. Intraoperative picture of the giant hydronephrosis with focus on the renal pedicle.

Figure 6

Pathologic specimen. Giant hydronephrotic right kidney, 35 × 30 × 25 cm in diameter with a weight of >15 kg.