Malignant rhabdoid tumor of the kidney combined with multicystic dysplasia in a 5-year-old child

Abstract

Multicystic dysplastic kidney (MCDK) is a relatively common developmental anomaly in infants and children and has a good prognosis. In contrast, a malignant rhabdoid tumor of the kidney (MRTK) is one of the most lethal neoplasms of early life. However, the presentation of such a lethal tumor combined with multicystic dysplasia has not been reported to date. In this report, we describe a case of MRTK in a 5-yr-old girl who also had multicystic dysplasia. She was previously diagnosed with MCDK at birth due to a huge palpable mass on the right side of the abdomen. The right kidney was extensively replaced by numerous grossly dilated, variable-sized cysts. Microscopically, the tumor cells show a diffusely infiltrative growth pattern, which revealed large non-cohesive, round-to-polygonal tumor cells with vesicular nuclei. Some tumor cells had eccentric nuclei and large, round, eosinophilic cytoplasmic inclusions. There were metanephrons present, with the central ureteric bud and peripheral branches surrounded by condensing mesenchyma, immature glomeruli, and metaplastic cartilage in the adjacent parenchyma. To our knowledge, this is the first combined case of the two aforementioned diseases and this case may, in fact, suggest a new disease entity.

Keywords: Childhood; Multicystic Dysplastic Kidney; Prognosis; Rhabdoid Tumor.

Fig. 1

Images of the abdomen. (A) Ultrasound showed a newly-developed amorphous echogenic lesion (asterisk) in the cyst, which suggests an infectious or tumorous change of the multicystic dysplastic kidney. (B) CT revealed a huge lobulated multicystic mass extensively replacing the right kidney.

Fig. 2

The removed right kidney, which measured 18×9×4 cm and weighed 250 g. (A) Its external surface has numerous cysts of variable sizes and gray-to-white discoloration. (B) The cut surface showed numerous cystic and semisolid masses (asterisk) in the cortex and medulla. The cysts were filled with yellow gelatinous material, dark brown necrotic material, and blood clots, measuring 6 cm in the largest diameter.

Fig. 3

Microscopic findings of the dysplastic kidney. (A) The kidney was composed of cysts and primitive tubules with individual tumor cells diffusely infiltrating the kidney parenchyma. (B) Metanephron (arrow head) surrounded by condensing mesenchyme and immature tubules. (C) A cartilage (arrow) is present. (D) High power microscopic findings of malignant rhabdoid tumor (pointed field (asterisk) of Fig. 3A). Tumor cells that are mostly large, loosely cohesive cells with acidophilic cytoplasm show a sheet-like growth pattern.

Fig. 4

Immunohistochemical staining findings. The rhabdoid tumor cells were positive for (A) cytokeratin, (B) vimentin, (C) INI1, and (D) epithelial membrane antigen.