Growth factors and receptors in juvenile nasopharyngeal angiofibroma and nasal polyps: an immunohistochemical study.

BACKGROUND: Juvenile nasopharyngeal angiofibroma is a rare nasopharyngeal tumor that occurs exclusively in adolescent boys. It is a histologically benign but locally persistent growth of stromal and vascular tissue. Although male hormones and some growth factors, such as transforming growth factor beta1 (TGF-beta1), insulin-like growth factor II (IGF-II), and, lately, the proto-oncogene beta-catenin, have been implicated in the histogenesis of the tumor, the biologic signaling pathways that drive this peculiar fibrovascular proliferation are still nuclear. OBJECTIVE: To evaluate immunoexpressions of beta-catenin, c-Kit, p130Cas, TGF-beta3, bone morphogenic protein 4, nerve growth factor (NGF), and the IGF receptor (IGF-1R) in a series of juvenile nasopharyngeal angiofibromas and to compare to that of a group of nasal polyps. DESIGN: A standard immunohistochemical technique was used on paraffin sections of 12 sporadic juvenile nasopharyngeal angiofibromas and 15 nasal polyps with microwave or steam antigen retrieval. Immunoreactivity was analyzed semiquantitatively in stromal cells and endothelial cells of each case. RESULTS: The expressions of beta-catenin (nuclear), c-Kit (cytoplasmic), and NGF (cytoplasmic) were higher and more frequent in stromal cells of juvenile nasopharyngeal angiofibromas than those of nasal polyps. Both juvenile nasopharyngeal angiofibromas and nasal polyps showed similarly frequent and strong immunoreactivity for p130Cas and TGF-beta3 and weak immunoreactivity for bone morphogenic protein 4 in both stromal cells and endothelial cells. No IGF-1R immunoreactivity was detected in any case of either group. CONCLUSIONS: Our results support the role of beta-catenin in juvenile nasopharyngeal angiofibromas and suggest a potential involvement of c-Kit and NGF signaling pathways in the juvenile nasopharyngeal angiofibromas. Although the biologic significance of c-Kit in juvenile nasopharyngeal angiofibromas has yet to be defined, the finding of frequent and high c-Kit expression might have therapeutic importance for patients with juvenile nasopharyngeal angiofibromas.

The role of calretinin, inhibin, melan-A, BCL-2, and C-kit in differentiating adrenal cortical and medullary tumors: an immunohistochemical study.

Morphologic distinction between adrenal cortical and medullary tumors can be difficult. Previous studies have shown inhibin, melan-A, and BCL-2 to be useful markers for adrenal cortical tumors. We have recently observed a high level of calretinin expression in normal adrenal cortex but not the medulla and therefore evaluated its diagnostic application for adrenal tumors in comparison with inhibin, melan-A, and BCL-2. C-kit is a transmembrane tyrosine kinase receptor. Immunodetection of c-kit expression has been recently used for tumor diagnosis, and c-kit-positive tumors can potentially benefit from kit kinase inhibitor treatment. Although c-kit expression was reported in adrenal medulla and pheochromocytoma, it has not been evaluated in adrenal cortical tumors. In this study, 28 adrenal cortical tumors (12 carcinomas, 16 adenomas), 20 pheochromocytomas, and 20 extraadrenal paragangliomas were evaluated for calretinin, inhibin, melan-A, BCL-2, and c-kit expression by standard immunohistochemical assays on paraffin sections. The percentage of immunoreactivity in adrenal cortical tumors was as follows: calretinin, 96%; melan-A, 89%; inhibin, 92%; BCL-2, 20%; and c-kit, 5%. Normal adrenal medulla did not stain for c-kit but was positive for BCL-2. Eighty-six percent of pheochromocytomas stained for BCL-2 and none for calretinin, with the exception of the ganglioneuromatous areas in composite pheochromocytomas (n = 5). Extraadrenal paragangliomas showed reactivity with calretinin in 25%, melan-A in 5%, inhibin in 16%, BCL-2 in 38%, and c-kit in 8% of the cases. Our results indicate that calretinin is the most sensitive among all the adrenal markers tested. Like melan-A and inhibin, calretinin is also a very specific marker in differentiating cortical from medullary adrenal tumors. In addition, calretinin can be used to confirm a composite pheochromocytoma. BCL-2 does not appear to be useful in differentiating adrenal cortical from medullary tumors. C-kit is not useful in the diagnosis of adrenal tumors, and kit kinase inhibitor might have a limited role in the treatment of adrenal tumors and paraganglioma because of the low frequency of c-kit expression in these tumors.

C-kit immunoreactivity in endometrial adenocarcinomas and its clinicopathologic significance.

The proto-oncogene c-kit is a transmembrane-tyrosine-kinase receptor that is structurally related to the platelet-derived growth-factor receptor (PDGFR) and is involved in cell differentiation. C-kit has been found to be expressed in certain solid tumors and may play a role in their tumorigenesis. Recently, a tyrosine-kinase inhibitor specific for the PDGFR family, bcr-abl, and c-kit (STI571) has been reported to have therapeutic effects in tumors expressing the aberrant forms or high quantities of target proteins. Expression of c-kit has not been well evaluated in endometrial adenocarcinomas. In this study, c-kit immunoreactivity was evaluated on paraffin sections of 72 endometrial adenocarcinomas (57 endometrioid, 10 serous, and 5 clear cell) with a polyclonal antibody. Immunoreactivity of c-kit was analyzed semiquantitatively and correlated with various clinicopathologic factors. Cytoplasmic c-kit immunoreactivity was detected in 42 (58%) tumors. Thirty-four (60%) endometrioid, 8 (80%) serous, and 0 of the 5 clear-cell adenocarcinomas were c-kit positive. There was a significant correlation between c-kit positivity and the depth of myometrial invasion. Patients with c-kit-positive endometrial adenocarcinomas more frequently had metastases and shorter disease-free survival. Expression of c-kit may be a potentially adverse prognostic feature in endometrial adenocarcinoma. Patients with c-kit-positive advanced endometrial adenocarcinoma might benefit from tyrosine-kinase-inhibitor therapy.

Immunophenotype of desmoplastic small round cell tumors as detected in cases with EWS-WT1 gene fusion product.

Desmoplastic small round cell tumor is a rare tumor typically involving peritoneum. Although the histogenesis of desmoplastic small round cell tumor has yet to be elucidated, immunophenotypical and morphological analysis shows a characteristic divergent phenotype overlapping with other round cell tumors such as Ewing's sarcoma/primitive neuroectodermal tumor, rhabdomyosarcoma, small cell mesothelioma, and carcinoma. Detection of the EWS-WT1 gene fusion is characteristic of desmoplastic small round cell tumor and has been used reliably in tumor diagnosis. In this study, we evaluated the immunophenotype of 23 desmoplastic small round cell tumor cases with the EWS-WT1 gene fusion product identified by reverse transcription-polymerase chain reaction. Paraffin sections were stained with antibodies against calretinin, WT1 (C19), desmin, myoglobin, MyoD, Myf5, myogenin, placental alkaline phosphatase, cytokeratins, MIC2, HER2/neu and c-kit using standard immunohistochemical methods. Immunoreactivity was evaluated semiquantitively by light microscopy. Desmoplastic small round cell tumors showed reactivity with calretinin in 4/21, desmin in 21/23, myoglobin in 5/17, placental alkaline phosphatase in 17/21, HER2/neu in 7/18 (3+ in 1 and 1+ in 6), c-kit in 2/14, MIC2 in 13/23, WT1 in 16/23, CAM5.2 in 21/23, and AE1/3 in 16/23 cases. The most sensitive myogenic and epithelial markers are desmin and CAM 5.2. Although nuclear reactivity of the early myogenic regulatory factors (MyoD, myogenin, Myf5) was not detected, myoglobin immunoreactivity was present in 29% of desmoplastic small round cell tumors. HER2/neu overexpression (3+) and c-kit expression are uncommon in desmoplastic small round cell tumors. A panel of myogenic and epithelial markers should be used to detect the divergent phenotype in desmoplastic small round cell tumors, a key feature in the differential diagnosis. Detection of EWS-WT1 fusion becomes critical for the diagnosis when the characteristic divergent phenotype cannot be detected immunohistochemically.