Thyroid Transcription Factor-1 Immunohistochemistry Research Articles

TTF-1: A Well-Favored Addition to the Immunohistochemistry Armamentarium as a Diagnostic Marker of SEGA

Subependymal giant cell astrocytoma (SEGA) is a World Health Organization grade 1 neoplasm, which, due to its dubious morphologic features, may be misdiagnosed as a high-grade tumor at times. This tumor shows binary immunoexpression including both glial and neural markers, leading to a state of diagnostic quandary. Recent evidences have surmised the diagnostic utility of thyroid transcription factor 1 (TTF-1), spurring us to study the practicality of this marker in distinguishing SEGAs from its mimics. In this study, TTF-1 immunohistochemistry using clone 8G7G3/1 (1:50) was performed in 38 cases of SEGA, 30 cases of central neurocytoma, 10 cases each of intraventricular glioblastoma and ependymoma, and 5 cases of cortical tubers. Additionally, serine/threonine-protein kinase B-Raf (BRAFV600E) mutation, a common genetic alteration in pediatric low-grade-glial tumors with neuronal-differentiation, was analyzed using Ventana immunohistochemistry platform. TTF-1 immunopositivity was seen in all 38 cases (100%) of SEGAs, with 20 cases (52.6%) showing diffuse (>50% of tumor area) expression while focal (<50%) immunopositivity was seen in 18 cases (47.3%). None of the cases demonstrated serine/threonine-protein kinase B-Raf immunolabeling. Barring 2 cases of neurocytoma (6.6%), all other cases including ependymoma, glioblastoma, and cortical tubers were immunonegative for TTF-1. The congruous finding of TTF-1 expression in SEGA and cells of the developing neuroepithelium in the medial ganglionic eminence hint toward a primogenitor cell with neoplastic potential in the presence of impelling factors.

Clinicopathological and molecular implications of aberrant thyroid transcription factor-1 expression in colorectal carcinomas: an immunohistochemical analysis of 1319 cases using three different antibody clones.

The precise profile of aberrant expression of thyroid transcription factor-1 (TTF-1) according to antibody clones in colorectal carcinomas (CRCs) has been controversial. Moreover, the detailed clinicopathological and molecular features of CRCs with TTF-1 expression have rarely been investigated. The aim of this study was to evaluate TTF-1 expression status in a large series of CRC cases by using three different antibody clones. Immunohistochemistry for TTF-1 with clones 8G7G3/1, SPT24 and SP141 was performed on tumour tissues of 1319 primary CRCs and 98 corresponding metastatic lesions. Among the 1319 CRCs, TTF-1 expression was detected in 68 cases by both clone SPT24 and clone SP141. TTF-1 expression was not detected in any of the cases when clone 8G7G3/1 was used. The 68 CRCs with TTF-1 expression detected by both clone SPT24 and clone SP141 were considered to be TTF-1-positive in this study. TTF-1 positivity was significantly associated with distal tumour location, non-mucinous histology, intact CDX2 expression and a low frequency of KRAS mutations in CRCs. Nearly all TTF-1-positive CRCs showed microsatellite-stable and CpG island methylator phenotype-negative statuses. TTF-1 positivity was also found in all metastatic lesions of the five TTF-1-positive primary CRCs. TTF-1 negativity was maintained in all metastatic lesions of the 93 TTF-1-negative primary CRCs. Our study confirmed that the frequency and characteristics of aberrant TTF-1 expression in CRCs vary according to the antibody clone. Aberrant TTF-1 expression detected by clone SPT24 or SP141 may be encountered preferentially in distally located, conventional pathway-type CRCs.

Metastatic Renal Cell Cancer to Thyroid Diagnosed by Endoscopic Ultrasound (EUS)-Guided Fine Needle Aspiration (FNA) Technique

Medical literature about the role of Endoscopic ultrasound (EUS) in identifying thyroid lesions is limited. We present a case of secondary thyroid cancer from renal cell carcinoma (RCC) metastasis, diagnosed by thyroid EUS-fine needle aspiration (FNA) approach that was done for staging of esophageal adenocarcinoma, in a patient with 11 years history of complete right nephrectomy for RCC. An 81 year old female patient presented to our facility with dysphagea to both solids and liquids. Initial EGD examination of the esophagus revealed a distal esophageal mass of 5 cm in length, that was biopsied, and the histopathologic results revealed esophageal adenocarcinoma. For staging, the patient underwent computed tomography (CT) of the chest, which showed the lower esophageal mass with mediastinal lymphadenopathy. Next, the patient underwent upper gastrointestinal (GI) EUS for assessment of the esophageal adenocarcinoma and the mediastinal lymph nodes. The EUS-FNA examination of the mediastinal lymph nodes revealed no lymphatic spread. A diagnosis of esophageal adenocarcinoma with stage of T3N0M0 was made. Upon withdrawing the EUS scope, examination of the thyroid revealed a hypoechoic, round, and well-demarcated mass that measured 26.9 mm x 21.9 mm in the right lobe (Image1A). The radial echoendoscope was then withdrawn and the Olympus video curvilinear array echoendoscope was advanced through the mouth into the proximal esophagus. Under echoendosonographic guidance, FNA with a 25-gauge needle (Expect EUS-FNA 25 G needle; Boston Scientific, Menomonie, WI, USA) was performed successfully without adverse events (Image 1B). Cytopathologist was present in the room and confirmed the adequacy of the sample. The thyroid FNA results showed renal cell carcinoma with positive Immunohistochemical stains for PAX8 and CAIX while negative for thyroid transcription factor-1 (TTF1), thyroglobulin and chromogranin (Image 2A-C). A diagnosis of metastatic RCC was made. The patient had a history of right renal cell carcinoma (RCC) status post right nephrectomy 11 years ago (Image 2D). The patient was referred for further oncology work up and management. In conclusion, diagnosis of metastatic RCC to thyroid by EUS-FNA approach during local staging of esophageal malignancy is feasible and safe.Figure: (A) EUS examination of the thyroid revealed a hypoechoic, round, and well-demarcated mass that measured 26.9 mm x 21.9 mm in the right lobe. (B) Under EUS guidance, FNA with a 25-gauge needle (Expect EUS-FNA 25 G needle; Boston Scientific, Menomonie, WI, USA) was performed successfully.Figure: (A) Cell block of thyroid nodule FNA is displaying multiple nests of clear cells, which have clear to eosinophilic cytoplasm. These nests are separated by delicate vascular network and surrounded by lymphocytic infiltrate (H&E stain, original magnification X 400). (B) Staining of Cell block with PAX-8 shows strong nuclear positivity (PAX-8 immunohistochemistry stain, original magnification X 200). (C) Staining the cell block with thyroid transcription factor-1 (TTF-1) shows negative staining (TTF-1 immunohistochemistry stain, original magnification X 200). (D) Kidney section is showing multiple nests of clear cells, which have clear to eosinophilic cytoplasm. These nests are separated by delicate vascular network (H&E stain, original magnification X 400).

An Integrated Molecular Analysis of Lung Adenocarcinomas Identifies Potential Therapeutic Targets among TTF1-Negative Tumors, Including DNA Repair Proteins and Nrf2.

Thyroid transcription factor-1 (TTF1) immunohistochemistry (IHC) is used clinically to differentiate primary lung adenocarcinomas (LUAD) from squamous lung cancers and metastatic adenocarcinomas from other primary sites. However, a subset of LUAD (15%-20%) does not express TTF1, and TTF1-negative patients have worse clinical outcomes. As there are no established targeted agents with activity in TTF1-negative LUAD, we performed an integrated molecular analysis to identify potential therapeutic targets. Using two clinical LUAD cohorts (274 tumors), one from our institution (PROSPECT) and The Cancer Genome Atlas, we interrogated proteomic profiles (by reverse phase protein array, RPPA), gene expression, and mutational data. Drug response data from 74 cell lines were used to validate potential therapeutic agents. Strong correlations were observed between TTF1 IHC and TTF1 measurements by RPPA (Rho = 0.57, P < 0.001) and gene expression (NKX2-1, Rho = 0.61, P < 0.001). Established driver mutations (e.g., BRAF and EGFR) were associated with high TTF1 expression. In contrast, TTF1-negative LUAD had a higher frequency of inactivating KEAP1 mutations (P = 0.001). Proteomic profiling identified increased expression of DNA repair proteins (e.g., Chk1 and the DNA repair score) and suppressed PI3k/mTOR signaling among TTF1-negative tumors, with differences in total proteins confirmed at the mRNA level. Cell line analysis showed drugs targeting DNA repair to be more active in TTF1-low cell lines. Combined genomic and proteomic analyses demonstrated infrequent alteration of validated lung cancer targets (including the absence of BRAF mutations in TTF1-negative LUAD), but identified novel potential targets for TTF1-negative LUAD, including KEAP1/Nrf2 and DNA repair pathways.

Relationship of thyroid transcription factor 1 to EGFR status in non-small-cell lung cancer.

Activating mutations of the epidermal growth factor receptor (EGFR) gene are known to drive a proportion of non-small-cell lung cancers. Identification of lung cancers harbouring such mutations can lead to effective treatment using one of the agents that targets and blocks egfr-mediated signalling. All specimens received at the BC Cancer Agency (Vancouver) for EGFR testing were prospectively identified and catalogued, together with clinical information and EGFR status, over a 14-month period. Specimens from 586 patients were received for EGFR testing, and EGFR status was reported for 509 patients. No relationship between specimen type or site of origin and EGFR test failure rate was identified. Concurrent immunohistochemical (ihc) status for thyroid transcription factor 1 (ttf1) was available for 309 patients. The negative predictive value of ttf1-negative status by ihc was 94.2% for predicting negative EGFR status. In patients with limited tissue available for testing, a surrogate for EGFR status would aid in timely management. Immunohistochemistry for ttf1 is readily available and correlates highly with EGFR status. In conjunction with genetic assays, ttf1 could be used to optimize an EGFR testing strategy.

Toward Personalized Medicine of Lung Cancer

We evaluated clinical parameters, histomorphology, and thyroid transcription factor 1 (TTF-1) immunoreactivity in 40 epidermal growth factor receptor (EGFR) mutation- and anaplastic lymphoma kinase (ALK) rearrangement-negative invasive pulmonary adenocarcinomas. Tumors were histomorphologically quantitated by a pulmonary pathologist and TTF-1 immunohistochemistry applied. EGFR mutation and ALK rearrangement status was determined with polymerase chain reaction/DNA sequencing and fluorescence in situ hybridization, respectively. Treatment response was related to type of treatment (P < .005) and clinical stage (P = .001). EGFR mutation- and ALK rearrangement-negative pulmonary adenocarcinomas containing papillary/micropapillary histology showed greater morphologic heterogeneity (P < .001), greater TTF-1 immunoreactivity (P = .004), and were more common in treatment responders (P < .05). These findings support that patients with pulmonary adenocarcinomas that are subject to nontargeted therapies may respond to treatment as a function of tumor cell differentiation with TTF-1 as a potential biomarker of this response.

Thyroid Transcription Factor-1 Is Not Expressed in Squamous Cell Carcinomas of the Lung

Thyroid transcription factor-1 (TTF-1) is one of the peripheral airway epithelial markers that, because it is commonly expressed in lung adenocarcinomas, but not in squamous cell carcinomas, is regarded as being useful in distinguishing between these 2 malignancies, especially in those instances in which the diagnosis cannot be made on routine histology. Even though it is generally believed that TTF-1 is not expressed in squamous cell carcinomas of the lung, a significant number of studies have reported positivity for this marker in up to 38% of the cases investigated. To determine the causes of these discrepancies, 85 pulmonary and 50 nonpulmonary squamous cell carcinomas (17 skin, 8 esophagus, 5 uterine cervix, and 20 from the head-and-neck region) were investigated by immunohistochemistry for TTF-1. None of the 85 squamous cell carcinomas of the lung showed reactivity in the neoplastic cells; however, because strong TTF-1 positivity was observed in the hyperplastic type II pneumocytes that were sometimes seen entrapped within the tumor, it is concluded that the presence of these entrapped cells was one of the most likely causes of the discrepancies. In addition, after a careful review of all of the previous publications on TTF-1 expression in squamous cell carcinomas of the lung, it was found that other factors, such as the type of antibody used and the selection of the cases, may have been the cause of the discrepancies.

Extrapulmonary small cell carcinoma: a clinicopathological study with identification of potential diagnostic mimics

To evaluate the clinicopathological features of small cell carcinoma arising outside the lung. Thirty-seven cases with a pathology diagnosis of extrapulmonary small cell carcinoma (EPSCC) were selected. The clinical notes were reviewed and tumour blocks were selected for a fresh haematoxylin and eosin (H&E) section and immunohistochemical stains. The most common tumour locations were cervix and bladder. Twenty-five cases (68%) were finally diagnosed as EPSCC, nine of which were found with coexisting non small cell carcinoma. Two cases (5%) were diagnosed as large cell neuroendocrine carcinoma (LCNEC) of the cervix. The remainder was classified as 10 poorly differentiated carcinomas (PDCs) (27%). Positive staining for thyroid transcription factor 1 (TTF-1) was noted in nine cases of EPSCC and in none of the cases of PDC (P = 0.034). Synaptophysin immunoreactivity was found in 20 cases of EPSCC and two cases of PDC with neuroendocrine differentiation (P = 0.002), as well as two cases of LCNEC. 34βE12 was positive in eight cases of SCC and two cases of PDC. Based on this series, EPSCC may be overdiagnosed. Immunohistochemistry for TTF-1, used in combination with synaptophysin, may help to discriminate EPSCC from PDC.

Abstract 3685: Analysis of EZH2 and TTF-1 protein expression identifies a subset of lung adenocarcinomas with better prognosis

Abstract Lung adenocarcinoma is a heterogeneous tumor with multiple phenotypes that have been associated with prognosis. Recently, we reported that in surgically resected adenocarcinomas, the presence of a solid histologic pattern is associated with poor prognosis. To characterize molecular targets and identify novel prognostic markers in lung adenocarcinoma, we examined by immunohistochemistry (IHC) and tissue microarrays (TMAs) the expression of 75 proteins in archival tumor tissues obtained from 204 surgically resected tumors. We selected two top markers, EZH2 (enhancer of zeste homolog 2) and TTF-1 (thyroid transcription factor-1) that had significant correlation with solid and bronchioloalveolar patterns, respectively, for more detailed clinico-pathologic analyses, including patients’ outcome. EZH2 is part of a protein complex that promotes cancer development by epigenetically silencing tumor suppressor genes. TTF-1 is a transcription factor considered a potential lineage-survival oncogene in lung cancer. For EZH2 and TTF-1 IHC expression analysis, we examined 320 surgically resected lung adenocarcinomas, stages I-III, with median follow-up of 6.7 years. EGFR and KRAS mutation data were available in most cases. High nuclear EZH2 expression in tumor cells correlated with younger patient age (P&amp;lt;0.0001), smoking history (P&amp;lt;0.0001), higher TNM stage (P=0.02), and lack of EGFR mutation (P=0.001). High nuclear TTF-1 expression correlated with female sex (P=0.002), smaller tumor size (P=0.001), lower TNM stage (P=0.02), and EGFR mutation (P=0.007). EZH2 and TTF-1 expression did not correlate with KRAS mutation status; however, we found that their expression levels were significantly higher (P=0.022 and P=0.005, respectively) in tumors with KRAS CYS substitution compared with other amino acid changes. Univariate and multivariate (adjusting by other clinical prognostic factors) analyses were used to correlate EZH2 and TTF-1 expression with recurrence-free survival (RFS) and overall survival (OS). In the multivariate analysis, high EZH2 expression (≥42, median score) was associated with worse RFS (P=0.028 HR 1.53) and OS (P=0.0002; HR 1.94), and high TTF-1 expression (&amp;gt;120 score) correlated with better OS (P=0.004; HR 0.62). We identified a subset (32%) of tumors with low-EZH2/high-TTF-1 that demonstrated better outcome in multivariate analysis, compared with other tumors, including RFS (P=0.004; HR 0.51) and OS (P=0.0007; HR 0.49). These tumors were more frequent in patients with female sex (P=0.003), never-smoking history (P=0.004), smaller tumor size (P=0.018), lower TNM stage (P=0.024), and EGFR mutation (P=0.0001). Our findings indicate that the combined analysis of the EZH2 and TTF-1 expression identifies a subset of lung adenocarcinoma patients with better outcome after surgical resection with curative intent. Supported by DoD grant W81XWH-07-1-0306 Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3685. doi:1538-7445.AM2012-3685

Combination of Napsin A and TTF-1 Immunohistochemistry Helps in Differentiating Primary Lung Adenocarcinoma From Metastatic Carcinoma in the Lung

Differentiation of primary from metastatic adenocarcinoma in the lung can be challenging, and it demands sensitive and specific biomarkers, especially when the tissue for diagnosis is limited. Thyroid transcription factor-1 (TTF-1) has been considered a reliable marker for adenocarcinoma of lung origin. However, several recent studies have shown that TTF-1 immunostaining is also positive in adenocarcinomas arising in different organs including colon, endometrium, endocervix, and ovary. In addition, approximately 20% of lung primary adenocarcinomas are negative for TTF-1 immunostaining, and napsin A immunostaining has slightly higher sensitivity in detecting lung primary adenocarcinoma. We performed TTF-1 and napsin A immunostaining on 120 cases of primary lung adenocarcinomas and 37 cases of metastatic carcinomas in the lung. The results showed that 95 (79.2%) of 120 lung primary adenocarcinomas showed napsin A+/TTF-1+ double-positive immunostaining pattern. TTF-1⁻/napsin A+, TTF-1+/napsin A⁻, and TTF-1⁻/napsin A⁻ were seen in 8.3%, 3.3%, and 9.2% lung primary adenocarcinomas, respectively. Eight (21.6%) of the 37 metastatic carcinomas were positive for TTF-1 and they include clear-cell renal cell carcinomas completely negative for napsin A although napsin A was detected in 12 (80.0%) of 15 primary papillary and 3 (33.3%) of 9 primary clear-cell renal cell carcinomas. All renal epithelial neoplasms were TTF-1 negative. These findings indicate that double napsin A and TTF-1-positive immunostaining is highly specific for lung primary adenocarcinoma and the combination of these 2 biomarkers is warranted to help segregating primary lung adenocarcinoma from metastatic carcinoma in the lung.

Diagnostic Use of PAX8, CAIX, TTF-1, and TGB in Metastatic Renal Cell Carcinoma of the Thyroid

Clear-cell renal cell carcinoma (ccRCC) may present with metastatic lesions in patients with a concurrent undiagnosed primary or a remote history of ccRCC. The thyroid is not uncommonly involved by metastatic ccRCC, in which a metastasis could be misinterpreted as a clear-cell change in adenomatoid nodules, follicular adenomas, or parathyroid glands. PAX8 is a transcription factor expressed by thyroid and renal-lineage cells. No previous study has evaluated the diagnostic use of PAX8 and ccRCC marker carbonic anhydrase IX (CAIX) in this setting. Cases of metastatic ccRCC in the thyroid (n=12), parathyroid glands and adenomas with clear-cell change (n=6), papillary thyroid carcinoma (n=6), thyroid follicular adenomas (n=5), and adenomatoid nodules with clear-cell change (n=5) were studied. Cases were assessed by standard immunohistochemistry for thyroid transcription factor-1 (TTF-1), thyroglobulin (TGB), PAX8, and CAIX. The extent and intensity of nuclear or cytoplasmic immunoexpression were assessed, with any labeling considered as a positive result. All metastatic ccRCCs were positive for PAX8 (moderate-to-strong, patchy-to-diffuse) and CAIX (strong, diffuse), and were negative for TTF-1 and TGB. All primary thyroid lesions labeled strongly and diffusely for TTF-1, TGB, and PAX8, and were negative for CAIX. Parathyroid tissues were negative for TTF-1, TGB, PAX8, and CAIX. An immunoprofile of "TTF1(-)/TGB(-)/CAIX(+)" was 100% sensitive and specific for metastatic ccRCC of the thyroid. The reverse profile "TTF1(+)/TGB(+)/CAIX(-)" supported a primary thyroid lesion. PAX8 was not useful in distinguishing metastatic ccRCC from thyroid lesions.

TTF-1 positive small cell cancers: Don’t think they’re always primary pulmonary!

Thyroid transcription factor 1 (TTF-1) plays a key role in morphogenesis of the lungs and is expressed in up to 90% of pulmonary small cell carcinomas. This explains why this marker is frequently used in the search for the primary origin of metastatic endocrine tumours. Here we report on a TTF-1 expressing mixed endocrine-exocrine carcinoma of the common bile duct in a patient with pulmonary nodules that did not appear to be neoplastic. TTF-1 positivity in pulmonary and extrapulmonary neuroendocrine tumours is reviewed, and we conclude that TTF-1 expression in neuroendocrine tumours of the small-cell type are not uncommon at extrapulmonary locations. Therefore, immunohistochemistry for TTF-1 in such tumours should be interpreted with caution.

Immunohistochemical Expression of Estrogen Receptor in Adenocarcinomas of the Lung

Immunohistochemistry for estrogen receptor may be used to distinguish metastatic breast cancers from adenocarcinomas of other sites, including those of the lung. The estrogen receptor exists as 2 subtypes, alpha and beta. Estrogen receptor alpha is the predominant subtype expressed by more than two-thirds of human breast cancers. Adenocarcinomas of lung origin may also express estrogen receptor, primarily the beta subtype. Human estrogen receptor alpha is highly homologous to estrogen receptor beta and consequently, antibodies used to detect estrogen receptor alpha in breast carcinomas may detect estrogen receptor beta in pulmonary adenocarcinomas. We investigated the immunohistochemical expression of estrogen receptor in proven primary lung adenocarcinomas using 3 anti-estrogen receptor alpha antibodies: mouse monoclonal 1D5, 6F11, and rabbit monoclonal SP1. Ninety-two pulmonary adenocarcinomas (53 women and 39 men) confirmed by clinical presentation and positive immunohistochemistry for thyroid transcription factor-1 (TTF-1) were included in this study. There were 19 incisional biopsies and 73 excisional specimens. Immunohistochemistry for estrogen receptor using antibodies 1D5, 6F11, and SP1 was performed on formalin-fixed, paraffin-embedded tissue following antigen retrieval. Any nuclear reactivity for estrogen receptor was considered a positive result. Focal positive nuclear reaction for estrogen receptor was detected in 7 (7.6%) cases of primary pulmonary adenocarcinoma using antibody 1D5, 13 (14.1%) using 6F11, and 25 (27.2%) using SP1. The differences in reactivity for estrogen receptor in pulmonary adenocarcinomas between SP1 and 1D5, and between SP1 and 6F11 were statistically significant (P<0.001). Positive cases showed only a focal pattern of staining with each of the 3 antibodies. There was no significant difference in reactivity for estrogen receptor in pulmonary adenocarcinomas of men and women. Positive staining was highest in nonmucinous bronchioloalveolar adenocarcinomas for all of the antibodies, and for SP1, variation by histologic subtype was significant (P<0.001). SP1 has a significantly higher detection rate for the expression of estrogen receptor in pulmonary adenocarcinomas when compared with either 1D5 or 6F11. Caution should therefore be exercised in the use of this antibody alone in distinguishing a metastatic breast from a primary pulmonary adenocarcinoma.

Napsin A and thyroid transcription factor-1 expression in carcinomas of the lung, breast, pancreas, colon, kidney, thyroid, and malignant mesothelioma

Recent advances in the treatment of pulmonary adenocarcinoma have increased the need for accurate typing of non-small cell carcinomas. Immunohistochemistry for thyroid transcription factor-1 is widely used in the diagnosis of pulmonary adenocarcinomas because it marks approximately 75% of lung adenocarcinomas and is negative in most squamous cell carcinomas and adenocarcinomas of other organs. Napsin A is an aspartic proteinase involved in the maturation of surfactant protein B. It is detected in the cytoplasm of type 2 pneumocytes and alveolar macrophages and is a putative marker for pulmonary adenocarcinomas. We performed immunohistochemistry for napsin A and thyroid transcription factor-1 using tissue microarrays of 95 adenocarcinomas, 48 squamous cell carcinomas, 6 neuroendocrine tumors of the lung, as well as 5 colonic, 31 pancreatic, and 17 breast adenocarcinomas, 38 malignant mesotheliomas, 118 renal cell carcinomas, and 81 thyroid tumors. The tissue microarrays also included 15 different benign tissues. Pulmonary adenocarcinomas were napsin A positive in 79 (83%) of 95 cases compared with 69 (73%) of 95 cases that were thyroid transcription factor-1 positive. There were 13 napsin A-positive/thyroid transcription factor-1-negative and 2 thyroid transcription factor-1-positive/napsin A-negative tumors, increasing the number of cases that were positive with at least one of the markers to 81 (85%) of 95. The limited number of neuroendocrine tumors tested was napsin A negative. All squamous cell carcinomas, adenocarcinomas of the colon, pancreas and breast, and mesotheliomas were negative for both markers. Of the renal tumors, napsin A was positive in most of papillary renal cell carcinomas (79%), about one third (34%) of clear cell renal cell carcinomas, and in a single case of chromophobe renal cell carcinoma (3%). In the thyroid, only 2 cases of papillary thyroid carcinoma (5%), both with tall cell morphology, were positive for napsin A, whereas all other papillary and follicular carcinomas were negative. As expected, all renal tumors were thyroid transcription factor-1 negative, and all thyroid tumors, except for one papillary carcinoma, were thyroid transcription factor-1 positive. Napsin A is a sensitive marker for pulmonary adenocarcinoma and is also expressed in a subset of renal cell carcinomas, particularly of the papillary type, as well as in rare cases of papillary thyroid carcinomas. The combined use of napsin A and thyroid transcription factor-1 results in improved sensitivity and specificity for identifying pulmonary adenocarcinoma in primary lung tumors and in a metastatic setting.

Thyroid transcription factor‐1 immunohistochemistry: diagnostic tool and malignancy marker in canine malignant lung tumours

Distinguishing primary lung carcinomas (PLCs) from metastases is a challenging task. The diagnostic and prognostic relevance of thyroid transcription factor-1 (TTF-1), a nuclear protein expressed in follicular cells of the thyroid gland and pneumocytes, was tested in 34 primary and 27 nonprimary canine lung tumours. Normal pneumocytes stained negatively in 14 PLCs because of overfixation or prolonged storage of paraffin blocks and were excluded from the study. Among the 20 immunoreactive PLCs, 17 showed strong nuclear positivity. The three tumours that scored negative were two squamous cell and one papillary carcinoma. Metastatic tumours were always negative. TTF-1 was 100% specific and 85% sensitive for PLCs. There was no significant relationship among the percentage of labelled tumour cells (TTF-1 index) and the considered clinicopathological parameters (age, gender, histological type, tumour grade, TNM stage, node status and MIB-1 index). TTF-1 immunohistochemistry may give useful additional information regarding the origin of canine lung tumours, whereas its prognostic use still needs to be determined.

Immunohistochemical Expression of Estrogen Receptor in Pulmonary Adenocarcinoma

Estrogen receptor (ER) is a useful immunohistochemical marker of breast carcinomas and is commonly used as a means of distinguishing breast carcinomas from adenocarcinomas of other primary sites, including the lung. Previous reports have yielded conflicting data regarding ER immunoreactivity in primary pulmonary adenocarcinomas. In this study the immunohistochemical expression of ER was evaluated in 55 primary lung adenocarcinomas using the 1D5 antibody clone. Immunohistochemistry for thyroid transcription factor-1 (TTF-1), a sensitive and specific marker of pulmonary adenocarcinomas, was also performed. ER expression was observed in 10 (18%) of 55 lung adenocarcinomas. Most of these pulmonary adenocarcinomas showed ER immunoreactivity of weak or moderate intensity (<25% of tumor cell nuclei). However, two cases exhibited strong ER immunoreactivity (51-75% of neoplastic cells). Forty-six (84%) of the 55 lung adenocarcinomas were TTF-1 positive, including all those that expressed ER. These results indicate that a subset of pulmonary adenocarcinomas can exhibit ER immunoreactivity. As such, caution should be exercised in the use of ER immunohistochemistry alone as a means of distinguishing breast carcinomas from lung adenocarcinomas. In the context of an ER-positive lung neoplasm, strong and extensive TTF-1 immunoreactivity can be regarded as strong supportive evidence for a primary bronchogenic adenocarcinoma.

The role of TTF-1 in differentiating primary and metastatic lung adenocarcinomas.

Thyroid transcription factor-1 (TTF-1) is a sensitive marker for pulmonary and thyroid adenocarcinomas. The aim of this work was to determine its usefulness in distinction between primary and metastatic lung adenocarcinomas. We have examined the expression of TTF-1 in 100 solitary pulmonary nodules. They included 50 stage I peripheral primary bronchial adenocarcinomas (30 men, 20 women, mean age: 60 years) and 50 metastatic pulmonary adenocarcinomas (21 men, 29 women, mean age: 57 years) of different origins, such as breast (13), colon (13), rectum (13), kidney (7), stomach (2), and thyroid gland (2). TTF-1 immunohistochemistry was performed on formalin-fixed, paraffin-embedded tissues. In primary bronchial adenocarcinomas we found immunopositivity in 46/50 cases, among them 30 cases showed strong nuclear immunostaining. In four primary adenocarcinoma cases the observed immunopositivity was localized to the cytoplasm. Out of the metastatic adenocarcinomas all but the 2 thyroid cancers were negative. Both thyroid tumors showed strong immunopositivity. Our results confirm that TTF-1 immunohistochemistry is a very sensitive and highly specific method in the differential diagnosis of primary and metastatic lung adenocarcinomas and should be used in the everyday clinical practice.

Immunohistochemical staining for thyroid transcription factor-1: A helpful aid in discerning primary site of tumor origin in patients with brain metastases

Metastatic carcinoma of unknown primary origin is a perplexing but common problem, accounting for up to 10% to 15% of all solid tumors at presentation. Many of these metastases presumably arise from primary lung carcinomas, but the morphologic features and immunohistochemical profile of lung cancer is often too nonspecific to permit unequivocal confirmation. Thyroid transcription factor-1 (TTF-1) is expressed in lung adenocarcinomas and thyroid carcinomas but not in adenocarcinomas arising from other sites. For patients with adenocarcinomas in the lung, TTF-1 staining is now routinely used to distinguish a primary lung cancer from a lung metastasis. Along these same lines, TTF-1 staining might prove useful in localizing the tumor origin of adenocarcinomas encountered outside of the lung. The archival surgical pathology files of The Johns Hopkins Hospital were searched for cases of brain metastases biopsied between 1990 and 2000. Tissue blocks were obtained and immunoperoxidase staining was performed using the TTF-1 antibody. The medical records were reviewed independent of the staining results to determine site of tumor origin. Seventy-five patients underwent biopsies of carcinomas metastatic to the brain. At the time of brain biopsy, the primary site of tumor origin was known in 45 cases and unknown in 30 cases. Ultimately, the primary site was established on clinical and radiographic grounds in 71 cases (95%). These included 40 (56%) metastases from a primary lung carcinoma and 31 (44%) metastases from some nonpulmonary carcinoma. TTF-1 staining was present in 31 of the 40 (78%) metastatic lung carcinomas, but in only 1 of the 31 (3%) metastatic nonpulmonary carcinomas (a small-cell carcinoma of the sinonasal tract). When the metastatic lung carcinomas were subtyped, TTF-1 staining was noted in 11 of 11 (100%) adenocarcinomas, in 6 of 7 (86%) small-cell carcinomas, in 15 of 19 (79%) large-cell carcinomas, and in none of 3 (0%) squamous cell carcinomas. TTF-1 staining is very reliable in discerning whether a brain metastasis has arisen from a pulmonary or nonpulmonary site, particularly when dealing with adenocarcinomas and large-cell carcinomas. TTF-1 immunohistochemistry could focus the search for the primary tumor for patients presenting with brain metastasis as the initial manifestation. HUM PATHOL 33:642-645. Copyright 2002, Elsevier Science (USA). All rights reserved.

Monoclonal antibody to thyroid transcription factor-1: production, characterization, and usefulness in tumor diagnosis.

Thyroid transcription factor-1 (TTF-1), a member of the NKx2 family of homeodomain transcription factors, is expressed in epithelial cells of the thyroid gland and the lung. To produce monoclonal antibodies specific for TTF-1, the polypeptide was expressed in E. coli and purified utilizing affinity chromatography of a polyhistidine-tagged TTF-1 fusion protein. Splenocytes from BALB/c mice immunized with recombinant TTF-1 were fused with P3x/63Ag8.653 myeloma cells to produce hybridomas. Tissue culture supernatant was screened for anti TTF-1 activity by ELISA employing recombinant TTF-1 as antigen. Hybridomas producing high-affinity antibodies were subcloned by limiting dilution. Antibodies from tissue culture fluid from an IgG1 clone (8G7G3/1) that stained the nuclei of paraffin-embedded human thyroid tissues were precipitation-purified and further characterized. The antibody stained a single 40-kDa polypeptide in immunoblots of nuclear extracts or lysates of cell lines known to express TTF-1 mRNA. MAb 8G7G3/1 also stained nuclei of tissue in a highly specific manner consistent with the pattern of expression obtained with an established polyclonal TTF-1 antibody and by in situ hybridization. MAb 8G7G3/1 was used for TTF-1 immunohistochemistry of human adenocarcinomas of the lung, colon, and breast as well as small cell carcinomas of the lung. TTF-1 was detected in primary lung adenocarcinomas and small cell carcinomas and was absent in colon and breast carcinomas. These findings demonstrate that anti-TTF-1 MAb 8G7G3/1 specifically binds TTF-1 in cell extracts and tissues and can be used to distinguish between lung and nonlung origin of a tumor.