Therefore, we utilized immunohistochemistry and FISH to study INI1 expression and 22q dosages, respectively, in 40 composite rhabdoid tumors, including 16 meningiomas, 15 carcinomas, three melanomas, two sarcomas, two glioblastomas, and 1 neuroblastoma.
This malignancy was most consistent with SMARCB1-deficient epithelioid malignant peripheral nerve sheath tumour, although a significant differential was proximal-type epithelial sarcoma.
Thus, alterations of the INI1 gene with consequent loss of expression identified a population of undifferentiated sarcomas lacking classic rhabdoid morphology in young patients, with evidence of favorable survival.
We evaluated BRG1 and INI1 expression in 12 SCCOHTs and in a series of 122 tumors that could mimic SCCOHT morphologically: 9 juvenile granulosa cell tumors, 47 adult granulosa cell tumors, 33 high-grade ovarian serous carcinomas, 9 desmoplastic round cell tumors, 13 Ewing sarcomas (5 from the pelvis and 8 from soft tissues), 1 round cell sarcoma associated with CIC-DUX4 translocation from soft tissue (thigh), 1 case of high-grade endometrial stromal sarcoma of the ovary, and 9 melanomas.
We analyzed the status of SMARCB1/INI1 protein expression in 93 cases of sarcomas associated with chromosomal translocation involving EWS, comprising 52 Ewing's sarcoma/primitive neuroectodermal tumors, 24 extraskeletal myxoid chondrosarcomas (EMCS), 14 clear cell sarcomas of soft tissue, 2 desmoplastic small round cell tumors, and 1 myxoid/round cell liposarcoma.
Among controls, only the SMARCB1-immunonegative myoepithelial carcinomas displayed SMARCB1 homozygous deletions in 3/5 cases, while no gene specific abnormalities were seen among all other histologic subtypes of sarcomas tested regardless of the SMARCB1 protein status.