NTRK expression is common in xanthogranuloma and is associated with the solitary variant.

BACKGROUND: Previously identified mutually-exclusive driver genes in juvenile xanthogranuloma (JXG) and adult xanthogranuloma (AXG) include mutations in MAP kinase pathway genes such as MAP2K1, BRAF, ARAF, KRAS, NRAS, PIK3CD as well as fusions in BRAF and ALK, with a subset of cases with no identified driver yet. NTRK fusion has been identified in rare cases. METHODS: We identified two consecutive index cases of localized JXG or AXG with NTRK1 fusion by next-generation sequencing (NGS) and confirmed by pan-NTRK immunostain. We expanded the study to a total of 50 cases of JXG and AXG using screening by pan-NTRK immunostain. We confirmed the specificity of our approach with negative results in 5 cases of histiocytic neoplasia lacking an NTRK fusion by NGS and 14 cases of non-neoplastic histiocytic disease. RESULTS: We found 23 cases of JXG or AXG with overexpression of NTRK by immunostain, and these cases were restricted to localized disease (23 of 43 cases, 53.5%) rather than disseminated disease (zero of seven cases). CONCLUSIONS: NTRK expression is common in JXG or AXG and associated with localized rather than disseminated disease. We speculate that the potential importance of this in JXG and AXG has not been previously appreciated due to the tendency to focus sequencing studies on disseminated disease. We confirm the presence of an NTRK1 fusion in two positive cases by NGS, however, additional genetic studies are necessary to further explore this.

Overexpression of Pim-1 during progression of prostatic adenocarcinoma.

AIMS: Pim-1 is a serine/threonine kinase that has been shown to play an integral role in the development of a number of human cancers, such as haematolymphoid malignancies. Recently, evidence has shown Pim-1 to be important in prostatic carcinogenesis. In order to further our understanding of its role in prostate cancer, we investigated Pim-1 expression in normal, premalignant, and malignant prostate tissue. METHODS: Using immunohistochemistry, Pim-1 expression was analysed in prostate tissue from 120 radical prostatectomy specimens. In each case, Pim-1 staining was evaluated in benign prostatic epithelium, high grade prostatic intraepithelial neoplasia (PIN), and prostatic adenocarcinoma. The number of positively staining cells was estimated, and the intensity of staining was scored on a scale of 0 to 3+. RESULTS: Pim-1 immunoreactivity was identified in 120 cases (100%) of adenocarcinoma, 120 cases (100%) of high grade PIN, and 62 cases (52%) of benign glands. The number of cells staining in benign epithelium (mean 34%) was much lower than that in high grade PIN (mean 80%; p<0.0001) or adenocarcinoma (mean, 84%; p<0.0001). There was no significant difference between high grade PIN and adenocarcinoma in the percentage of cells staining positively for Pim-1 (p = 0.34). The staining intensity for Pim-1 was significantly lower in benign prostatic epithelium than in PIN and adenocarcinoma (p<0.001). There was no statistically significant correlation between the level of Pim-1 expression and Gleason score, patient age, tumour stage, lymph node metastasis, perineural invasion, vascular invasion, surgical margin status, extraprostatic extension, or seminal vesicle invasion. CONCLUSIONS: Pim-1 expression is elevated in PIN and prostatic adenocarcinoma compared with benign prostatic epithelium. This finding suggests that upregulation of Pim-1 may play a role in prostatic neoplasia.

Autocrine activation of PDGFRalpha promotes the progression of ovarian cancer.

Platelet-derived growth factor receptor (PDGFR)alpha expression was found in ovarian cancer cells and tumors by microarray hybridization. This led us to test whether ovarian cancers also produce ligands for this receptor, as this would demonstrate that such malignancies support their own growth and spread through autocrine activation. We assayed the expression of ligands for the PDGFR in ovarian tumors, cell lines and peritoneal fluid using RT-PCR, immunohistochemistry (IHC) and ELISA. We detected strong mRNA expression for the PDGFRalpha ligands in most ovarian tumors. Receptor and ligand expressions (PDGFRalpha and PDGF AB) were also detected by IHC in, respectively, 34 and 32 of 47 ovarian tumors. The stainings for PDGFRalpha and PDGF AB were strongly correlated (P-value=0.014), suggesting that an autocrine loop is functional in ovarian cancer. PDGF AA and BB were quantified in peritoneal fluid by ELISA. Both ligands are secreted at higher levels in ovarian cancer ascites specimens (n=54) than in fluid from nonmalignant disorders (n=8). PDGF was detected in media conditioned by ovarian cancer cells. Such conditioned media induced activation of the PDGFR, Akt and MAPK and stimulated cell proliferation. A neutralizing PDGF antibody blocked these effects. Specific PDGFR inhibition by siRNA or a neutralizing antibody to the receptor inhibited PDGF-stimulated receptor activation and cell proliferation, suggesting that receptor targeting has a role in ovarian cancer treatment.

HER-2/neu expression in germ cell tumours.

AIMS: To determine the rate of HER-2/neu positivity of germ cell tumours by immunohistochemistry (IHC) and by fluorescence in situ hybridisation (FISH). PATIENTS/METHODS: Ninety six archival, paraffin wax embedded pathology specimens were chosen from four groups of germ cell tumours. IHC for HER-2/neu was performed with the HercepTest kit; FISH analysis was performed with the INFORM assay and confirmed with a centromere 17 probe. RESULTS: Twenty two of 96 specimens overexpressed the HER-2/neu protein when measured by IHC. Only three specimens showed HER-2/neu gene amplification by FISH. There was no correlation between the results obtained by IHC and FISH. CONCLUSIONS: The lack of concordance between IHC and FISH makes it unlikely that overexpression of the HER-2/neu protein in germ cell tumours is of prognostic or therapeutic relevance. Because of the low rate of HER-2/neu gene amplification in germ cell tumours, a clinical trial of trastuzumab treatment in patients with germ cell tumours is not warranted.