Abstract
The SMARCB1/INI1 gene was first discovered in the mid-1990s, and since then it has been revealed that loss of function mutations in this gene result in aggressive rhabdoid tumors. Recently, the term “rhabdoid tumor” has become synonymous with decreased SMARCB1/INI1 expression. When genetic aberrations in the SMARCB1/INI1 gene occur, the result can cause complete loss of expression, decreased expression, and mosaic expression. Although SMARCB1/INI1-deficient tumors are predominantly sarcomas, this is a diverse group of tumors with mixed phenotypes, which can often make the diagnosis challenging. Prognosis for these aggressive tumors is often poor. Moreover, refractory and relapsing progressive disease is common. As a result, accurate and timely diagnosis is imperative. Despite the SMARCB1/INI1 gene itself and its implications in tumorigenesis being discovered over two decades ago, there is a paucity of rhabdoid tumor cases reported in the literature that detail SMARCB1/INI1 expression. Much work remains if we hope to provide additional therapeutic strategies for patients with aggressive SMARCB1/INI1-deficient tumors.
Highlights
The SMARCB1/integrase interactor 1 (INI1) gene was first discovered in the mid-1990s, and since it has been revealed that loss of function mutations in this gene result in aggressive rhabdoid tumors
In addition to epithelioid sarcoma (ES), atypical teratoid/rhabdoid tumor, renal medullary carcinoma, and pediatric chordoma are rare sarcomas that result from the complete loss of SMARCB1/INI1 expression (Table 1)
We reviewed the literature and found a paucity of cases reporting SMARCB1/INI1 genetic aberrations in adult patients with sarcomas
Summary
Any reports and responses or comments on the article can be found at the end of the article. In addition to ES, atypical teratoid/rhabdoid tumor, renal medullary carcinoma, and pediatric chordoma are rare sarcomas that result from the complete loss of SMARCB1/INI1 expression (Table 1) They predominantly occur in pediatric or young adult patients. Rare SMARCB1/INI1-deficient tumors that occur more commonly in adults include synovial sarcomas, epithelioid malignant peripheral nerve sheath tumor, myoepithelial carcinoma, extraskeletal myxoid chondrosarcoma, chordoma, schwannomatosis, gastrointestinal stromal tumors (GIST), and ossifying fibromyxoid tumor (Table 1). On light microscopy, these sarcomatous neoplasms exist on a morphological spectrum.
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