Rhabdoid morphology in gastrointestinal stromal tumours (GISTs) is associated withPDGFRAmutations but does not imply aggressive behaviour

Genomic mapping of pathways in endometrial adenocarcinoma and a gastrointestinal stromal tumor located in Meckel's diverticulum

The present study reports the case of a 71-year-old female patient diagnosed with endometrial adenocarcinoma, which was confirmed by histopathology. In the course of performing an elective hysterectomy with adnexa removal, a solid tumor located in Meckel's diverticulum (MD) was identified and excised. Due to the unique nature of the lesion, the tumor tissue underwent broad mapping of any genomic alterations once the histopathological examination was completed. The genetic testing was conducted using a high-resolution microarray and resulted in the identification of 45 genomic abnormalities, including 4 chromosomal aneuploidies. Within those regions, alterations of 87 known cancer genes were assigned. The involvement of v-kit Hardy-Zuckerman 4 feline sarcoma viral oncogene homolog gene alteration was noted to be a key player for triggering gastrointestinal stromal tumor transformation for this unusual case. A total of 12 genes, showing mutual interaction in different cancer types or involved in diverse cellular processes, were identified. These reported data may shed light on the carcinogenesis of a rare MD tumor.

Rhabdomyosarcomatous Transformation of a Gastrointestinal Stromal Tumor following Treatment with Imatinib

Rhabdomyosarcomatous dedifferentiation of GIST following tyrosine kinase inhibitor (TKI) therapy is rare, with only a handful of cases previously reported in the literature. Herein we present a case of metastatic GIST initially treated with imatinib that developed radiographic evidence of progression after 8 months of standard dose therapy with continued progression despite attempts at using dose-escalated imatinib 400 mg bid. Due to the patient's worsening clinical symptoms and radiographic concerns for colonic thickening, abscess, and extraluminal air, the patient underwent a palliative resection of a large heterogeneous mass arising from the posterior stomach and several metastatic foci. Pathology revealed a dedifferentiated GIST with rhabdomyosarcomatous features. This report will highlight the unique features of this case and review the existing literature.

The expanding family of SMARCB1(INI1)-deficient neoplasia: implications of phenotypic, biological, and molecular heterogeneity

Since the description of atypical teratoid/rhabdoid tumors of the central nervous system and renal/extrarenal malignant rhabdoid tumors in children, the clinicopathologic spectrum of neoplasms having in common a highly variable rhabdoid cell component (0% to 100%) and consistent loss of nuclear SMARCB1 (INI1) expression has been steadily expanding to include cribriform neuroepithelial tumor of the ventricle, renal medullary carcinoma and a subset of collecting duct carcinoma, epithelioid sarcoma, subsets of miscellaneous benign and malignant soft tissue tumors, and rare rhabdoid carcinoma variants of gastroenteropancreatic, sinonasal, and genitourinary tract origin. Although a majority of SMARCB1-deficient neoplasms arise de novo, the origin of SMARCB1-deficient neoplasia in the background of a phenotypically or genetically definable differentiated SMARCB1-intact "parent neoplasm" has been convincingly demonstrated, highlighting the rare occurrence of rhabdoid tumors as "double-hit neoplasia." As a group, SMARCB1-deficient neoplasms occur over a wide age range (0 to 80 y), may be devoid of rhabdoid cells or display uniform rhabdoid morphology, and follow a clinical course that varies from benign to highly aggressive causing death within a few months irrespective of aggressive multimodality therapy. Generally applicable criteria that would permit easy recognition of these uncommon neoplasms do not exist. Diagnosis is based on site-specific and entity-specific sets of clinicopathologic, immunophenotypic, and/or molecular criteria. SMARCB1 immunohistochemistry has emerged as a valuable tool in confirming or screening for SMARCB1-deficient neoplasms. This review summarizes the different phenotypic and topographic subgroups of SMARCB1-deficient neoplasms including sporadic and familial, benign and malignant, and rhabdoid and nonrhabdoid variants, highlighting their phenotypic heterogeneity and molecular complexity.