Malignant rhabdoid tumour of Kidney (MRTK) is an aggressive renal tumour considered
, and often affecting very young children (mean
About 13% of patients develop second midline primitive brain tumours.
MRTK is associated with hypercalcaemia.
Classical pattern is of "rhabdoid" cells with large eosinophilic central nucleoli and eosinophilic cytoplasmic inclusions which indent the nucleus. There are many other patterns including epithelioid, sclerosing, histiocytoid, lymphomatoid etc.
The cells co-express vimentin, cytokeratin, often EMA (Epithelial membrane antigen) and occasionally other markers.
Electron microscopy shows the inclusions to be composed of whorls of cytoplasmic filaments with a few included organelles and lipid droplets.
Other renal tumours may simulate MRT or show rhabdoid features. These include Wilms' tumour itself, renal cell carcinoma, cellular examples of mesoblastic nephroma, and medullary cell carcinoma.
Extra-renal rhabdoid tumour is a controversial entity, and has now been described in many sites. Many turn out to be other tumours (neural, epithelial, myoid, mesenchymal, ependymal) when fully investigated.
While renal rhabdoid tumours peak in infancy, reports of extrarenal rhabdoid tumours show a bimodal pattern with a peak in infancy and a second peak in older children tailing into adulthood.
Extra-renal rhabdoid tumours seldom have second intracranial tumours or cause the hypercalcaemia seen with renal rhabdoid tumours.
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