Malignant Rhabdoid Tumor



Malignant Rhabdoid Tumor


Satish K. Tickoo, MD

Victor E. Reuter, MD





Key Facts


Terminology



  • Malignant rhabdoid tumor of kidney (RTK)


  • Highly malignant pediatric renal tumor with very poor prognosis and genetic abnormalities of hSNF5/INI1 tumor suppressor gene on chromosome 22


Etiology/Pathogenesis



  • Biallelic inactivation of gene, located at 22q11.2; consistent feature of RTK


Clinical Issues



  • Mean age of presentation: Around 1 year old


  • Predominantly affects younger children; 80% < 2 years old, 60% < 1 year old


  • Overwhelming majority of stage IV renal tumors in 1st 7 months of life are RTK


  • High tumor stage at presentation


Macroscopic Features



  • Well-circumscribed and unencapsulated


  • Foci of hemorrhage and necrosis


Microscopic Pathology



  • Sheets of monotonous, loosely cohesive, large ovoid to polygonal cells, with high nuclear grade


  • Characteristic cytologic features: Vesicular chromatin, prominent eosinophilic nucleoli, and intracytoplasmic hyaline, pink inclusion, at least in some cells


Ancillary Tests



  • SNF5(INI1) negative immunostaining considered specific



    • Reliable surrogate marker of hSNF5/INI1 gene deletion or inactivating mutations







RTK is seen with necrosis image, irregular invasive borders image, and extension beyond renal parenchyma image. Necrosis may be more extensive, and some tumors may be relatively small due to early dissemination.






Sheets of loosely cohesive tumor cells with large nuclei and abundant eosinophilic cytoplasm are typical of RTK. A delicate network of fibrovascular septae image may also be appreciated.


TERMINOLOGY


Abbreviations



  • Malignant rhabdoid tumor of kidney (RTK)


Definitions



  • Highly malignant pediatric renal tumor with very poor prognosis and genetic abnormalities of hSNF5/INI1 tumor suppressor gene on chromosome 22


ETIOLOGY/PATHOGENESIS


HSNF5/INI1 Tumor Suppressor Gene



  • Biallelic inactivation of gene, located at 22q11.2; consistent feature of RTK



    • Usually associated with deletion of 1 copy with mutation in remaining copy


    • Gene believed to be important for chromatin remodeling


CLINICAL ISSUES


Epidemiology



  • Incidence



    • Comprises approximately 2% of pediatric renal tumors


  • Age



    • Mean age of presentation around 1 year


    • Predominantly affects younger children; 80% < 2 years old, 60% < 1 year old



      • Virtually nonexistent after 5 years of age


    • Overwhelming majority of stage IV renal tumors in 1st 7 months of life are RTK


  • Gender



    • M:F = 1.5:1


Site



  • Originally described in kidney; similar tumors later recognized in extrarenal sites, including



    • Central nervous system (atypical teratoid/rhabdoid tumor) and soft tissue

Tags:
Jul 7, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Malignant Rhabdoid Tumor

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