A GRIA2 and PAX8-positive renal solitary fibrous tumor with NAB2-STAT6 gene fusion

Abstract

Solitary fibrous tumor (SFT) is a rare neoplasm composed of mesenchymal-derived spindle cells. Although SFT occurs anywhere in the body, they most frequently affects the thoracic region. Here, we reported an extremely rare case of an extrathoracic SFT occurring primarily in the kidney. To our knowledge, little information has been described on the immunohistochemistry (IHC) and genetics of renal SFT.A 41-year old Japanese female came to our hospital for further examination of a left kidney mass detected incidentally with ultrasound. Extensive investigation of the tumor, including physical, laboratory, and image examinations led to a clinical diagnosis of renal cancer (cT1aN0M0), which were in most parts imbedded in the lower polar parenchyma. The patient underwent laparoscopic radical nephrectomy. The mass was diagnosed pathologically as SFT originating from the kidney, but not as renal carcinoma. Microscopically, the tumor was composed of spindle-shape cells distributed variably in dense collagenous stroma and had a focal hemangiopericytomatous staghorn-like vascular pattern. Mitotic figures, atypical structures, necrosis and hemorrhage were not identified. No adjuvant therapies were given postoperatively. The patient has been free of tumor recurrence for 25 months since the surgery. IHC revealed that the tumor diffusely expressed CD34, CD99, Bcl2, PAX8, NAB2, STAT6, and GRIA2. The tumor stained negatively for desmin, S-100, c-Kit, CK-AE1/AE3, CDK4 and MDM2. A NAB2-SATA6 gene fusion was detected in tumor cells by reverse transcription-polymerase chain reaction, direct sequencing, and an in situ proximity ligation brightfield assay. The gene fusion occurred as an 831 bp truncation of exon 2 in NAB2 connected to the beginning of exon 3 in STAT6. We have reported a case of GRIA2 and PAX8-positive SFT occurring primarily in the kidney with such NAB2-STAT6 gene fusion for the first time. Diffuse expression of PAX8 in the tumor might present with a renal origin. Reportedly, benign histology of SFT cannot necessarily predict favorable clinical prognosis. Genetic alterations recently identified in SFT could possibly refer to risk stratification for tumor recurrence. However, malignant preponderance of extrathoracic SFT over thoracic SFT remains unexplained so far. Long-term follow-up after surgery should be performed in the present case.Electronic supplementary materialThe online version of this article (doi:10.1186/s13000-015-0386-x) contains supplementary material, which is available to authorized users.

NAB2‐STAT6 gene fusion and STAT6 immunoexpression in extrathoracic solitary fibrous tumors: the association between fusion variants and locations

“…8,15 Ranking the second, NAB2ex4-STAT6ex2 still occurred in one third of our cases. Intriguingly, the detection rate of other miscellaneous fusion variants appeared dependent on different sub-sites of extrathoracic SFTs, which, in our series and when combined with previously documented cases (Table 3), 4,8,[16][17][18][19][20][21] was both significantly rare for body cavity-based tumors. This finding was in sharp contrast with SFTs occurring in the head and neck, where various miscellaneous variants were In the presence of amplifiable housekeeping PGK mRNA, cases 11-15 showed no detectable fusion transcript by RT-PCR (right gel).…”

Levels of 4EBP1/eIF4E Activation in Renal Cell Carcinoma Could Differentially Predict Its Early and Late Recurrence

“…A standard previously reported staining procedure was used. 16 In brief, tissue sections (3 mm) obtained from the FFPE specimens were deparaffinized in xylene and rehydrated. Endogenous peroxidase was blocked with 3% hydrogen peroxide in methanol for 15 minutes.…”

Expression of Extracellular Signal-regulated Kinase 5 and Ankyrin Repeat Domain 1 in Composite Pheochromocytoma and Ganglioneuroblastoma Detected Incidentally in the Adult Adrenal Gland

“…These findings suggest that the tumor behavior and prognosis of composite PCs are greatly influenced by the type of neural components involved. According to Wang et al ( 40 ), copy number gain (1 to 9 copies more than CEP2 gene) and amplification (at least 10 copies greater than those) of the N-myc gene were observed in 78.1% and 3.1% of 32 patients with GNBLs and NBLs, respectively. They also demonstrated that N-myc gain was a favorable prognostic factor in 220 pediatric patients with neuroblastic tumors, compared with a normal and amplified status of the N-myc gene.…”

“…The immunohistochemical staining methods ( 38 , 40 ) and fluorescence in-situ hybridization analyses used in the present report are described in detail in the supplementary file ( Supplementary file 2 ).…”