If it's not CK5/6 positive, TTF-1 negative it's not a squamous cell carcinoma of lung

Novel targeted treatment of non-small cell lung cancer (NSCLC) requires accurate classification of NSCLC as squamous cell carcinoma (SCC) and adenocarcinoma (AC). This study details the CK5/6 and TTF-1 immunoprofile of surgical resections of 45 NSCLCs (24 ACs and 21 SCCs) in tissue microarrays. All SCCs were CK5/6 positive, TTF-1 negative. 20 of 24 adenocarcinomas had the reverse pattern. In conclusion, all SCCs in this study were CK5/6 positive and TTF-1 negative, and therefore tumours that do not display this phenotype are unlikely to be SCCs. CK5/6 and TTF-1 is therefore a practical panel for the distinction between pulmonary SCC from AC in routine histopathology practice.     

Napsin A Expression in Subtypes of Thyroid Tumors: Comparison with Lung Adenocarcinomas

Napsin A is widely used in the diagnosis of lung adenocarcinoma and has also been reported to be positive in cases of thyroid carcinomas. We investigated napsin A levels through immunohistochemistry on whole sections of 210 primary thyroid tumors of various subtypes and another 41 metastatic thyroid carcinomas, and compared these with 125 primary and 25 metastatic lung adenocarcinomas. The results showed that napsin A was expressed in 23.8% thyroid tumors and 30.3% papillary thyroid carcinomas. Most cases showed a focal and weak to moderate expression. In comparison, 80.8% primary lung adenocarcinomas expressed napsin A, with mostly diffused and strong expression. For metastatic carcinomas of thyroid and lung origin, napsin A was detected in 39.0% of thyroid carcinomas in contrast to 88.0% in cases of lung adenocarcinomas. Comparisons of additional markers, TTF-1, CK7, thyroglobulin, and Pax-8 in metastatic carcinomas showed the overlapping expression of immunomarkers of TTF-1 and CK7. Thyroglobulin and Pax-8 were useful for distinguishing between metastatic carcinomas; however, Pax-8 may be a superior marker due to its higher sensitivity. The clinicopathological analysis of papillary thyroid carcinomas showed that the expression of napsin A was positively correlated with lymph node metastasis (p = 0.030). Here, we focused on the expression of napsin A in thyroid tumors and compared it with that in lung adenocarcinomas. The expression of napsin A is common in thyroid tumors and the combined expression of napsin A and TTF-1 in a metastatic thyroid carcinoma is a cause for concern due to chances of misdiagnosis as lung adenocarcinoma.

     

Evaluation of epithelial and keratin markers in glioblastoma multiforme: an immunohistochemical study.

OBJECTIVE: Poorly differentiated metastatic carcinoma may be difficult to distinguish histologically from high-grade astrocytic malignant neoplasms, particularly on small open or stereotactic biopsy specimens. Previous authors have reported that a subset of glioblastoma multiforme (GBM) variably stains with cytokeratin immunomarkers. The authors examined a panel of epithelial and keratin antibodies by paraffin immunohistochemistry to evaluate the immunophenotype of GBM for these markers and to determine what combination of immunostains would be optimal in distinguishing GBM from metastatic carcinoma. METHODS: Twenty-three patients with GBM (age range, 19-86 years; mean, 63.4 years; 14 men and 9 women) and 22 patients with metastatic carcinoma (age range, 26-77 years; mean, 58.1 years; 7 men and 15 women) to the brain were studied with a panel of immunostains, including glial fibrillary acid protein (GFAP), Ber-EP4, antikeratin monoclonal antibodies AE1/3, and antibodies to CAM 5.2 and cytokeratins 7 (CK7) and 20 (CK20). Sites of origin for the metastatic tumors included lung (n = 11), breast (n = 5), endometrium (n = 1), prostate (n = 1), colon (n = 1), presumed kidney (n = 1), and unknown (n = 2). RESULTS: All GBMs stained positive for GFAP (100%), and all but 1 (95.7%) stained positive for cytokeratins AE1/3. Only rare focal immunoreactivity was observed in a single case of GBM with CAM 5.2 (4.3%), CK7 (4.3%), and CK20 (4.3%). Immunoreactivity with Ber-EP4 was not observed in any of the GBMs (0.0%). All cases of metastatic carcinoma stained positive with cytokeratins AE1/3 (100%) and CAM 5.2 (100%). Variable staining was observed in carcinomas with CK7 (17 of 22, 77.3%), Ber-EP4 (11 of 22, 50.0%), and CK20 (9 of 22, 40.9%). Three metastatic carcinomas showed rare GFAP-positive staining cells (13.6%). CONCLUSIONS: Based on the aforementioned results, a combination of immunostains, including GFAP and cytokeratin CAM5.2, may be the most useful in differentiating poorly differentiated metastatic carcinoma from GBM. A significant number of GBMs stain with some cytokeratin markers, in particular cytokeratins AE1/3. Because of the poor specificity of cytokeratins AE1/3 in distinguishing metastatic carcinoma from GBM, it should not be used to differentiate the 2 entities.     

Large cell carcinoma of the lung: clinically oriented classification integrating immunohistochemistry and molecular biology

This study aimed at challenging pulmonary large cell carcinoma (LLC) as tumor entity and defining different subgroups according to immunohistochemical and molecular features. Expression of markers specific for glandular (TTF-1, napsin A, cytokeratin 7), squamous cell (p40, p63, cytokeratins 5/6, desmocollin-3), and neuroendocrine (chromogranin, synaptophysin, CD56) differentiation was studied in 121 LCC across their entire histological spectrum also using direct sequencing for epidermal growth factor receptor (EGFR) and v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations and FISH analysis for ALK gene translocation. Survival was not investigated. All 47 large cell neuroendocrine carcinomas demonstrated a true neuroendocrine cell lineage, whereas all 24 basaloid and both 2 lymphoepithelioma-like carcinomas showed squamous cell markers. Eighteen out of 22 clear cell carcinomas had glandular differentiation, with KRAS mutations being present in 39 % of cases, whereas squamous cell differentiation was present in four cases. Eighteen out of 20 large cell carcinomas, not otherwise specified, had glandular differentiation upon immunohistochemistry, with an exon 21 L858R EGFR mutation in one (5 %) tumor, an exon 2 KRAS mutation in eight (40 %) tumors, and an ALK translocation in one (5 %) tumor, whereas two tumors positive for CK7 and CK5/6 and negative for all other markers were considered adenocarcinoma. All six LCC of rhabdoid type expressed TTF-1 and/or CK7, three of which also harbored KRAS mutations. When positive and negative immunohistochemical staining for these markers was combined, three subsets of LCC emerged exhibiting glandular, squamous, and neuroendocrine differentiation. Molecular alterations were restricted to tumors classified as adenocarcinoma. Stratifying LCC into specific categories using immunohistochemistry and molecular analysis may significantly impact on the choice of therapy.     

Immunohistochemical profile of normal mesothelium and histiocytic/methothelial hyperplasia: a case report

Immunohistochemical profiles of normal mesothelium and histiocytic/mesothelial hyperplasia (HMH) are unknown. A 19-year-old man was treated by thoracoscopic resection of bullae of left lung. Histologically, there were cell proliferative foci composed of round cells without significant atypia (histiocyte, mesothelium and T-lymphocytes). The cell proliferative foci were patch-like, and no invasive features were seen. Because it is composed of histiocytes, mesothelium, and T-lymphocytes, the diagnosis was HMH. Immunohistochemically, cell components of HMH showed the following immunoreactions: calrenitin 3+, D2-40 3+, pancytokeratin AE1/3 3+, pancytokeratin CAM5.2 3+, cytokeratin (CK) 34βE12 1+, CK5/6 1+, CK7 1+, CK8 3+, CK 14 1+, CK18 2+, CK19 2+, p53 10%, Ki67 20%, CD68 3+, CD45 2+, CD45 RO 2+, vimentin 3+, Ber-EP4 -, CK20 -, EMA -, desmin -, CEA -, CA19-9 -, TTF-1 -, S100 protein -, αsmooth muscle actin -, CD34 -, CD20 -, chromogranin -, synaptophysin -, NSE -, CDX2 -, CD56 -, HER2 -, MUC1 -, MUC2 -, MUC5AC -, and MUC6 -. The normal mesothelium showed the following immunoprofile: calrenitin 3+, D2-40 3+, pancytokeratin AE1/3 3+, pancytokeratin CAM5.2 3+, CK34βE12 3+, CK5/6 2+, CK7 2+, CK8 3+, CK 14 -, CK18 3+, CK19 2+, vimentin 1+, p53 -, Ki67 1%, CD68 -, CD45 -, CD45 RO -, Ber-EP4 -, CK20 -, EMA -, desmin -, CEA -, CA19-9 -, TTF-1 -, S100 protein -, α-smooth muscle actin -, CD34 -, chromogranin -, synaptophysin -, NSE -, CDX2 -, CD56 -, HER2 -, MUC1 -, MUC2 -, MUC5AC -, and MUC6 -. These findings indicate that the immunoprolfile of mesothelium in HMH was immunohistochemically very similar to that of normal mesothelium except for CD68, p53 protein, Ki-67 labeling, CD45 and CD45 RO. These indicate that the HMH was reactive phenomenon and HMH is composed of hyperplastic mesothelium, histiocytes and T-lymphocytes. The immunoprofile of normal mesothelium provide basic knowledge of mesothelial pathology.