title: Retroperitoneal undifferentiated pleomorphic sarcoma having microsatellite instability associated with Muir-Torre syndrome: case report and review of literature.
abstract: Muir-Torre syndrome represents a rare autosomal dominant familial cancer predisposition disorder defined by the occurrence of cutaneous sebaceous tumors and an internal malignancy, most commonly gastrointestinal carcinoma. Most examples of hereditary non-polyposis cancer syndrome (Lynch syndrome), including the Muir-Torre syndrome, are associated with microsatellite instability (MSI) and germline mutations in mismatch repair genes-most commonly MLH1 or MSH2. We present a 58-year-old man with Muir-Torre syndrome and a large retroperitoneal mass (14.3 cm in greatest dimension) encompassing the left adrenal gland. Sections showed a cellular malignant tumor composed of spindle cells with a high mitotic index and lacking morphologic evidence of adipocytic differentiation. It was weakly reactive for smooth muscle actin (SMA) and negative for desmin, CD117, CD31, CD34, S100 protein and pan-cytokeratin. Further immunohistochemical analysis revealed intact expression of MLH1 but loss of MSH2 in tumor nuclei. Compared to non-neoplastic tissue, the tumor showed MSI in five of seven dinucleotide markers. Fluorescence in situ hybridization (FISH) failed to reveal 12q15 amplification, effectively excluding dedifferentiated liposarcoma as a diagnostic consideration. This is a rare case of a patient with Muir-Torre syndrome who developed a related high-grade undifferentiated pleomorphic sarcoma as the associated internal malignancy.
authors.affiliation: Department of Pathology, Methodist Hospital, Houston, TX, USA.
authors.forename: Nathan
authors.initials: N
authors.lastname: Lee
authors.forename: Rajyalakshmi
authors.initials: R
authors.lastname: Luthra
authors.forename: Dolores
authors.initials: D
authors.lastname: Lopez-Terrada
authors.forename: Wei-Lien
authors.initials: WL
authors.lastname: Wang
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Lazar
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism; D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism; D043171:Chromosomal Instability; D018095:Germ-Line Mutation; D006801:Humans; D008297:Male; D018895:Microsatellite Repeats; D008875:Middle Aged; D055653:Muir-Torre Syndrome / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein / Q000235:genetics / Q000378:metabolism; D016609:Neoplasms, Second Primary / Q000378:metabolism / Q000473:pathology; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D012186:Retroperitoneal Neoplasms / Q000473:pathology; D009418:S100 Proteins / Q000235:genetics / Q000378:metabolism; D012509:Sarcoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D015703:Antigens, CD; C501486:MLH1 protein, human; D009687:Nuclear Proteins; D009418:S100 Proteins; C497172:MSH2 protein, human; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein
keywords: MSH2; Muir-Torre; microsatellite instability; sarcoma