Kendra Curless

Detection of BRAF Mutations on Direct Smears of Thyroid Fine-Needle Aspirates Through Cell Transfer Technique

OBJECTIVES To determine the utility of the cell transfer technique (CTT) for BRAF molecular testing on thyroid fine-needle aspiration (FNA) specimens. METHODS Polymerase chain reaction (PCR)-based BRAF molecular testing was performed on tissues obtained through CTT from both air-dried and ethanol-fixed direct smears of thyroid FNA specimens and then compared with the corresponding thyroidectomy formalin-fixed, paraffin-embedded (FFPE) tissues on 30 cases. RESULTS BRAF testing was successfully performed on 29 of 30 air-dried CTT, 27 of 30 ethanol-fixed CTT, and 27 of 30 FFPE tissues. The results exhibited 11, 13, and 13 BRAF mutations and 18, 14, and 14 wild types for the air-dried CTT, the ethanol-fixed CTT, and the FFPE tissues, respectively. The concordance rate was 96% between air-dried and ethanol-fixed CTT tissues, 88% between air-dried CTT and FFPE tissues, and 92% between ethanol-fixed CTT and FFPE tissues. CONCLUSIONS PCR-based BRAF mutational testing can be reliably performed on the direct smears of the thyroid FNA specimens through the application of CTT.

Mucinous intrahepatic cholangiocarcinoma: a distinct variant

Mucinous variant of intrahepatic cholangiocarcinoma (iCC) is rare, and its clinicopathological features and prognosis are far less clear. Six patients who had iCCs with more than 50% of mucinous component and 79 conventional iCCs were included in the study. The mean size of mucinous and conventional iCCs was 6.2 and 6.0 cm, respectively. Most patients (83%) with mucinous iCC presented at T3 stage or above compared with 28% of the conventional group (P < .01). Three patients with mucinous iCC (50%) died within 1 year. The average survival time of patients with mucinous iCCs was significantly reduced compared with that of the conventional group (9 months versus 2 years; P < .001). Immunohistochemistry was performed on 6 mucinous and 12 conventional iCCs with matched age, sex, and stage, which revealed positive immunoreactivity in MUC1 (83% versus 58%), MUC2 (33% versus 17%), MUC5AC (100% versus 42%), MUC6 (50% versus 0), CK7 (83% versus 83%), CK20 (0 versus 17%), CDX2 (17% versus 0), p53 (67% versus 67%), Smad4 (67% versus 58%), and EGFR (83% versus 42%) in mucinous and conventional iCCs, respectively. Molecular studies showed one mucinous iCC with KRAS G12C mutation and no BRAF or IDH1/2 mutations. Mucinous iCC is a unique variant that constitutes 7% of iCCs. It is more immunoreactive for MUC1, MUC2, MUC5AC, and MUC6. Unlike adenocarcinomas of colorectal primary, mucinous iCCs are often CK7+/CK20-/CDX2- and microsatellite stable. Patients with mucinous iCC likely present at advanced stage upon diagnosis with shorter survival time compared with the conventional counterparts.

Distinct clinicopathological features in metanephric adenoma harboring BRAF mutation

BRAF mutation recently has been reported in metanephric adenoma. We sought to determine the clinical and morphologic features of BRAF-mutated metanephric adenoma and to correlate BRAF mutation with BRAF V600E immunohistochemical staining results. A series of 48 metanephric adenomas and 15 epithelial-predominant nephroblastomas were analyzed for the occurrence of BRAF mutation (BRAF V600E/V600E complex, BRAF V600D, BRAF V600K and BRAF V600R) using the BRAF RGQ PCR kit (Qiagen). Immunohistochemistry was performed using monoclonal mouse antibodies against p16INK4 and VE1 (Spring Bioscience), recognizing the BRAF V600E mutant protein. Forty-one of 48 cases (85%) showed BRAF V600E mutation; none of the other BRAF variants was detected. Of 41 BRAF-mutated metanephric adenomas, 33 showed positive VE1 immunostaining (sensitivity 80%, specificity 100%); in all cases we detected p16INK4 expression regardless of BRAF mutation status. All epithelial-predominant nephroblastomas were BRAF-wild-type and none expressed VE1. The following features were associated with BRAF V600E mutation: older patients (p=0.01), female predominance (p=0.005) and the presence of a predominantly acinar architecture (p=0.003). In summary, BRAF-mutated metanephric adenomas were associated with older age, female predominance, and the presence of a predominant acinar component. A subset (20%) of BRAF-mutated metanephric adenomas was not detected by VE1 immunostaining.

Diagnostic utility of IDH1/2 mutations to distinguish dedifferentiated chondrosarcoma from undifferentiated pleomorphic sarcoma of bone

Histologically, it is nearly impossible to distinguish the dedifferentiated component of dedifferentiated chondrosarcoma from undifferentiated pleomorphic sarcoma (UPS) of bone when the low-grade cartilaginous component is absent. Previous studies have revealed that isocitrate dehydrogenase 1 (IDH1) and IDH2 mutations are present in a significant number of cartilaginous tumors including most conventional chondrosarcomas and dedifferentiated chondrosarcomas. These mutations have not been studied in UPSs of bone. We sought to investigate whether an IDH1 or IDH2 mutation signature could be used as a clinically diagnostic marker for the distinction of dedifferentiated component of chondrosarcoma from UPS of bone. Sixty-eight bone tumor cases, including 31 conventional chondrosarcomas, 23 dedifferentiated chondrosarcomas, and 14 UPSs of bone, were collected for IDH1/2 mutation analysis either using the Qiagen IDH1/2 RGQ PCR Kit or using whole-exome sequencing. IDH1/2 mutations were detected in 87% (20/23) of dedifferentiated chondrosarcomas and 30% (6/20) of conventional chondrosarcomas. No mutations were detected in the IDH1/2 codon 132 or codon 172 among 14 UPSs of bone. Identification of IDH1 or IDH2 mutations supports the diagnosis of dedifferentiated chondrosarcoma rather than UPS of bone while also providing some insight into the pathogenesis of these 2 lesions.