Malignant extrarenal rhabdoid tumour (MERT) is a rare soft-tissue neoplasm that occurs in children and young adults.
Given their highly aggressive nature, early diagnosis of rhabdoid tumours is essential.
Death usually occurs within 2 years.
Metastases occur early to lungs, liver and lymphnodes.
Site: It was first described as as renal tumour, subsequently the tumour was found in soft tissue and in other sites.
Cases have involved numerous extrarenal sites, including the thymus, liver, paravertebral region, central nervous system, heart, prostate, pelvis, chest wall, extremities, as well as soft tissues.
Age: Most patients are infants or children.
1. Round or epitheloid cells with hyaline globular cytoplasmic inclusions and very large nucleoli within vesicular nuclei.
2. Deep and homogeneous acidophilic cytoplasm of the tumor cells is characteristic.
3. Myxoid, pseudoalveolar and hyalinized areas may be seen.
Molecular genetic analysis: Demonstrates deletion or mutation of the hSNF5/INI1 gene, with corresponding reduced expression at the protein level.
Immunohistochemistry: Consistent positivity for cytokeratin, Epithelial Membrane Antigen (EMA) and vimentin. S-100 protein is usually negative.
INI1 antibody immunohistochemistry is useful in confirming the histologic diagnosis of renal or extra-renal rhabdoid tumor, especially for cases with indeterminate histologic features.
Electron microscopy: Inclusions are paranuclear aggregates of intermediate filaments.
Image and article link: Ettore Marzano, Emilie Lermite, Cinzia Nobili, et al., “Malignant Rhabdoid Tumour of the Liver in the Young Adult: Report of First Two Cases,” HPB Surgery, vol. 2009, Article ID 628206, 4 pages, 2009. doi:10.1155/2009/628206
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