Comparison of thyroid transcription factor-1 expression by 2 monoclonal antibodies in pulmonary and nonpulmonary primary tumors

Utility of a Highly Specific and Sensitive Podoplanin/D2-40, Calretinin, Thyroid Transcription Factor-1, and Carcinoembryonic Antigen/CD66e Immunohistochemical Panel in Differentiating Malignant Pleural Mesothelioma from Metastatic Adenocarcinoma: An Egyptian Experience

Background and Objective

Considering plentiful immunohistochemical (IHC) antibodies, a selection of highly sensitive and specific targeted panels is necessary to differentiate malignant pleural mesothelioma (MPM) from metastatic adenocarcinoma. We aimed to examine the sensitivity and specificity of four markers (podoplanin [PDPN]/D2-40, calretinin, thyroid transcription factor-1 [TTF-1], and carcinoembryonic antigen [CEA]/CD66e) as an initial IHC panel of Egyptian patients with malignant pleural biopsies.

Materials and Methods

Forty Egyptian malignant pleural biopsies with histomorphological features of mesothelioma versus adenocarcinoma were immunohistochemically stained by PDPN/D2-40, calretinin, TTF-1, and CEA/CD66e.

Results

PDPN/D2-40 and calretinin were positive in 27/27, 100% of mesothelioma cases with 100% sensitivity, 96.4% specificity for PDPN/D2-40, and 100% sensitivity and specificity for calretinin. Membranous PDPN/D2-40 expression was strong in 14 cases (53.85%), moderate in eight cases (30.77%), and weak in four cases (15.38%), while pure cytoplasmic staining was reported in one case. Calretinin was predominantly nuclear in all mesothelioma cases. TTF1 and CEA/CD66e were negative in all mesothelioma cases. In adenocarcinomas, PDPN/D2-40 was only expressed as weak cytoplasmic staining in 1/13 cases, while calretinin was negative in all 13 cases. Nuclear TTF1 and cytoplasmic CEA/CD66e immunostaining positivity were reported in all adenocarcinoma cases (13/13) with 100% sensitivity and specificity for both markers.

Conclusion

The combination of PDPN/D2-40, calretinin together with CEA/CD66e, and TTF1 may be highly valuable in differentiating MPM from metastatic adenocarcinoma.

Unlocking Precise Lung Cancer Detection Through Minimal Panel Immunostaining in Small Biopsy Samples

Introduction Lung cancer diagnosis faces challenges due to morphological heterogeneity and limited biopsy tissue. This study evaluates the efficacy of a minimal panel immunostaining technique using immunohistochemical markers like napsin A, thyroid transcription factor 1 (TTF-1), p63, and synaptophysin to improve the precision of lung carcinoma subclassification. Methods A retrospective analytical study was conducted at the Histopathology Laboratory of Saveetha Medical College and Hospital, Chennai, from January 2018 to February 2024. A total of 64 lung carcinoma cases were analyzed. Inclusion criteria included biopsy samples from lung lesions with a confirmed diagnosis of lung carcinoma based on histomorphological examination, covering all age groups and both genders. Non-carcinomatous lung lesions were excluded. Clinical data were obtained from the Medical Information Archiving Software (MIAS) database and histopathological examination request forms. Under a light microscope, tissue samples were examined after being fixed in formalin, processed, and stained with hematoxylin and eosin (H&E). Additionally, a minimal panel of immunohistochemical markers, including napsin A, TTF-1, p63, and synaptophysin, was used to subclassify lung carcinomas. Results The age group older than 50 years was the most affected, with a higher incidence in males. Histologically, 49% of cases were adenocarcinoma, 42% were squamous cell carcinoma, and 9% were small cell carcinoma. Immunohistochemistry (IHC) results adjusted these proportions to 54.6% adenocarcinoma, 31.2% squamous cell carcinoma, and 14% small cell carcinoma, showing a 5.6% increase in adenocarcinoma cases. The most common adenocarcinoma pattern was mixed, followed by acinar. TTF-1 and napsin A were crucial for identifying adenocarcinoma, while p63 was key for squamous cell carcinoma. Synaptophysin confirmed neuroendocrine differentiation in small cell carcinoma. Conclusion Incorporating a minimal panel of IHC markers significantly enhances the accuracy of lung carcinoma subclassification, addressing diagnostic challenges posed by morphological heterogeneity and limited sample size. This approach supports more precise and efficient clinical care for patients with lung cancer. Further validation in diverse clinical settings is recommended.

Pitfalls in Respiratory Tract Cytopathology

BACKGROUND

Cytopathology is integral to the investigation and diagnosis of respiratory disease, and, in the last decade or so, transbronchial needle aspiration by endobronchial ultrasound has made possible diagnosis and staging of malignant thoracic tumours at a single procedure. In addition, interventional teams increasingly include cytopathologists and cytotechnologists who, by providing rapid onsite evaluation, ensure efficient sampling of intrathoracic targets with the ultimate goal of accurate diagnosis as well as sufficient material for comprehensive predictive testing. Nonetheless, "traditional" cytological investigations such as bronchial washings, brushings, and lavages are still carried out for investigation of both suspected neoplastic and non-neoplastic conditions, and all these procedures still produce specimens in which florid benign cells mimic malignancy, while truly neoplastic cells lurk quietly in the background. Furthermore, even when neoplasia is not suspected, issues in preparation and interpretation may render a final assessment inaccurate and, therefore, clinically unhelpful or misleading. In this overview, we have tried to adopt a format partly modelled on the passage of a specimen from clinical acquisition to laboratory endpoint, thus taking in potential pitfalls in communication, clinical interaction, transport, and clinic-based preparation, as well as in morphology, immunocytochemistry, and suitability for predictive testing. It is not exhaustive but highlights areas that may frequently be encountered or are part of our personal experience.

SUMMARY

The account highlights potential pitfalls in respiratory cytopathology at key stages of the process from acquisition to reporting and presents these in both flow diagram and tabular form. We hope this is useful for the increasingly collaborative roles of cytotechnologist and cytopathologist and their wider involvement in the clinical investigative teams.

KEY MESSAGES

Correct clinical and radiological information is crucially important and promotes the correct acquisition and processing of cytopathological specimens. Cross-discipline collaborative working ensures the most efficient use of the specimen such that diagnoses and predictive tests are performed on optimal material, reducing the potential for misinterpretation. Nonetheless, even with optimal material, morphological mimics and atypical antigen expression may mislead and render accurate diagnosis challenging.

Patterns of Immunoreactivity with TTF-1 Antibodies 8G7G3/1 and SPT24 Suggest Distinct Immunoprofiles Between Most Pulmonary and Nonpulmonary Small Cell Carcinomas

Introduction. Small cell carcinoma can arise from various sites. Herein, we analyze the ability of 2 thyroid transcription factor-1 (TTF-1) antibodies (SPT24 and 8G7G3/1) to separate pulmonary from nonpulmonary small cell carcinoma. Materials and Methods. We analyzed 26 pulmonary and 83 nonpulmonary small cell carcinomas, and 14 Merkel cell carcinomas. Each tumor was stained with SPT24 and 8G7G3/1. Extent of nuclear staining was scored as diffuse (>50%), focal (11%-50%), rare (1%-10%), or negative (<1%). Results. All pulmonary small cell carcinomas were positive for SPT24 and 8G7G3/1. Four Merkel cell carcinomas (29%) were positive for SPT24 (ranging from rare-to-diffuse), while 2 (14%) showed rare expression with 8G7G3/1. For nonpulmonary small cell carcinomas, 69 (83%) were positive for SPT24 and 40 (48%) were positive for 8G7G3/1. For SPT24 positive tumors, the extent of 8G7G3/1 expression was equal in 17 (25%) and less in 52 tumors (75%), including 29 (42%) that were negative for 8G7G3/1. No nonpulmonary small cell carcinoma had more staining with 8G7G3/1 compared to SPT24. The differences in staining between 8G7G3/1 and SPT24 in the nonpulmonary cohort were statistically significant (P < 0.0001) with no significant difference between primary and metastatic lesions for 8G7G3/1 (P  =  0.66) or SPT24 (P  =  0.77). Conclusion. Most pulmonary small cell carcinomas are diffusely positive for both SPT24 and 8G7G3/1, whereas most nonpulmonary small cell carcinomas exhibit focal-to-no staining with 8G7G3/1 and significantly less staining with 8G7G3/1 compared to SPT24. However, these trends are not absolute and should be interpreted in conjunction with clinical and radiological findings.

Utility of Immunohistochemistry in the Diagnosis of Pleuropulmonary and Mediastinal Cancers: A Review and Update

CONTEXT.—

Immunohistochemistry has become a valuable ancillary tool for the accurate classification of pleuropulmonary and mediastinal neoplasms necessary for therapeutic decisions and predicting prognostic outcome. Diagnostic accuracy has significantly improved because of the continuous discoveries of tumor-associated biomarkers and the development of effective immunohistochemical panels.

OBJECTIVE.—

To increase the accuracy of diagnosis and classify pleuropulmonary neoplasms through immunohistochemistry.

DATA SOURCES.—

Literature review and the author's research data and personal practice experience.

CONCLUSIONS.—

This review article highlights that appropriately selecting immunohistochemical panels enables pathologists to effectively diagnose most primary pleuropulmonary neoplasms and differentiate primary lung tumors from a variety of metastatic tumors to the lung. Knowing the utilities and pitfalls of each tumor-associated biomarker is essential to avoid potential diagnostic errors.

Carcinoma of unknown primary (CUP): an update for histopathologists

Carcinoma of unknown primary (CUP) is a heterogeneous group of metastatic cancers in which the site of origin is not identifiable. These carcinomas have a poor outcome due to their late presentation with metastatic disease, difficulty in identifying the origin and delay in treatment. The aim of the pathologist is to broadly classify and subtype the cancer and, where possible, to confirm the likely primary site as this information best predicts patient outcome and guides treatment. In this review, we provide histopathologists with diagnostic practice points which contribute to identifying the primary origin in such cases. We present the current clinical evaluation and management from the point of view of the oncologist. We discuss the role of the pathologist in the diagnostic pathway including the control of pre-analytical conditions, assessment of sample adequacy, diagnosis of cancer including diagnostic pitfalls, and evaluation of prognostic and predictive markers. An integrated diagnostic report is ideal in cases of CUP, with results discussed at a forum such as a molecular tumour board and matched with targeted treatment. This highly specialized evolving area ultimately leads to personalized oncology and potentially improved outcomes for patients.

Predictive Impact of Diffuse Positivity for TTF-1 Expression in Patients Treated With Platinum-Doublet Chemotherapy Plus Immune Checkpoint Inhibitors for Advanced Nonsquamous NSCLC

Introduction

Pervious studies reported the association of TTF-1 expression with the efficacy of platinum-doublet chemotherapy in combination with immune checkpoint inhibitors in advanced nonsquamous NSCLC. Nevertheless, the predictive value of extent of TTF-1 expression (diffuse or focal TTF-1 positivity) remains unclear.

Methods

The present study retrospectively reviewed 74 patients with TTF-1-positive recurrent or advanced nonsquamous NSCLC receiving first-line chemoimmunotherapy in a single institution in Japan. TTF-1 expression score in pretreatment tumor specimens was evaluated using immunohistochemistry, and the impact of chemoimmunotherapy response was analyzed.

Results

In the total cohort, ≥50% of the tumor cells were TTF-1 positive (i.e., diffusely TTF-1 positive) in specimens of 61 patients (82.4%), whereas 10% to 49% of the tumor cells were TTF-1 positive (i.e., focally TTF-1 positive) in specimens of the remaining 13 patients (17.6%). In multivariate analysis, the median progression-free survival and overall survival (OS) were significantly longer in patients with diffusely TTF-1-positive tumors than in those with focally TTF-1-positive tumors (14.2 versus 9.2 mo, p = 0.01 and 30.2 versus 17.3 mo, p = 0.01, respectively). Moreover, the median OS was significantly longer in patients receiving chemoimmunotherapy including pemetrexed than in those receiving chemoimmunotherapy not including pemetrexed among the patients with diffusely TTF-1-positive tumors (not attained versus 23.2 mo, p < 0.01).

Conclusions

The positive extent of diffuse TTF-1 expression associated with patient outcome was an independent predictive factor for better progression-free survival and OS in patients with advanced nonsquamous NSCLC receiving chemoimmunotherapy.

Metastatic small cell lung cancer presenting as acute appendicitis: a case report

We present a case of extensive stage small cell lung cancer presenting as perforated appendicitis secondary to an appendiceal metastasis. This is a rare presentation with only six reported cases in the literature. Surgeons must be aware of unusual causes for perforated appendicitis as in our case the prognosis can be dire. A 60-year-old man presented with an acute abdomen and septic shock. Urgent laparotomy and a subtotal colectomy were performed. Further imaging suggested the malignancy was secondary to a primary lung cancer. Histopathology demonstrated a ruptured small cell neuroendocrine carcinoma in the appendix with thyroid transcription factor 1 positive immunohistochemistry. Unfortunately, the patient deteriorated due to respiratory compromise and was palliated day six postoperatively. Surgeons should consider a broad differential diagnosis for the cause of acute perforated appendicitis as this can rarely be due to a secondary metastatic deposit from a widespread malignant process.

Medullary thyroid carcinoma diagnosed with liquid-based cytology and immunocytochemistry

Medullary thyroid carcinoma (MTC) is a rare neuroendocrine malignancy that arises from the parafollicular cells (C cells) secreting calcitonin. This study summarizes our experience in the diagnosis of MTC with ultrasound-guided thyroid FNA, subsequently processed with liquid-based cytology (LBC) and immunocytochemistry (ICC). We searched our laboratory archives for thyroid FNA cases with an interpretation of positive or suspicious for MTC, during the period 2004-2018. A total of 20 cases (18 thyroid FNAs; two lymph node FNAs) were selected and included in this study. These displayed high cellularity and a discohesive pattern, with a few loose syncytial groups. There was some variation in the cell size and shape both across and within our cases. Most MTCs (n = 15) exhibited a predominant plasmacytoid/epithelioid cell morphology, whereas five of our cases showed a spindle cell pattern. Of interest, none of eight MTC microcarcinomas (≤1 cm) showed a spindle cell morphology. Amyloid was found in 11/20 cases (55%), while binucleation/multinucleation in 17/20 (85%), and nuclear pseudoinclusions in 3/20 MTC cases (15%). Nuclei exhibited a granular, "salt and pepper" chromatin in all cases. ICC was performed in 18/20 cases (90%). Calcitonin, CEA, TTF1, and Chromogranin were positive wherever applied, whereas thyroglobulin and CK19 were negative. In conclusion, ultrasound-guided thyroid FNA - processed with LBC and ICC - is a reliable modality to detect MTC preoperatively, facilitating the management of such patients.

Fine-needle aspiration cytology of metastatic carcinomas with papillary architecture: a systemic assessment of clinical, cytologic and immunohistochemical parameters

BACKGROUND

Papillary structures are frequently encountered in metastatic carcinomas from various organs and tumors of different histotypes. This study aims to investigate the predictive value of fine-needle aspiration cytology (FNAC), immunohistochemistry (IHC) and clinical parameters in assessment of primary sites of metastatic carcinomas with papillary architecture.

METHODS

FNAC of metastatic carcinomas with papillary architecture were evaluated for overall cellularity, epithelial cohesion, background features, architecture of papillae, cytology and IHC. The corresponding clinical information were also reviewed.

RESULTS

Totally 130 cases were included. The most common primaries were thyroid (38.5%), lung (30.8%) and gynecological organs (22.3%) with the remainders being pancreaticobiliary, urothelial, colorectal, and esophageal. Age (p=.039), biopsy site (p<.001) and laterality (p=.006) correlated with primary site. Papillary structures were confirmed on biopsy/excision of most cases (n=85/87, 97.7%). Thyroid primaries demonstrated broad papillary stalks, thin lining epithelium, fewer epithelial polymorphs, and presence of background giant cells and histiocytes (p=.021-<.001). Low-grade cytologic features, nuclear grooves and inclusions (p<.001) were seen in thyroid primaries. High-grade features (p<.001-0.49), multinucleated tumor cells, apoptotic bodies and mitoses (p<.001-0.49) were more common in lung/gynecological primaries. Multivariate analysis identified nuclear/cytoplasmic ratio, chromatin character, presence of nuclear groove and mitosis as independent features (p=0.001-.024). TTF1/TGB/PAX8 panel demonstrated good agreement with cytologic assessment and primary site.

CONCLUSION

Papillary structures and cytologic features are reproducible in FNACs of metastases and corresponding primaries. Cytologic features, IHC and clinical information are invaluable in determining the primary site.

Thymic Adenocarcinoma with Positivity for Thyroid Transcription Factor-1 and a BRAF V600E Mutation

Thymic adenocarcinomas are rare. We herein report for the first time a case of thymic adenocarcinoma with positivity for thyroid transcription factor-1 (TTF-1) and a BRAF V600E mutation. A 50-year-old woman had persistent suffocation and chest pain. Computed tomography revealed a 42×28-mm tumor in the anterior mediastinum. The patient underwent tumor resection using video-assisted thoracoscopic surgery. Histopathological findings showed thymic papillary adenocarcinoma, Masaoka stage II. Immunohistochemically, the tumor was positive for TTF-1. A sequencing analysis revealed a BRAF V600E mutation. The patient underwent postoperative radiotherapy and was in good health without recurrence at five months after resection.

Real-World Diagnostic Accuracy and Use of Immunohistochemical Markers in Lung Cancer Diagnostics

OBJECTIVES

Accurate and reliable diagnostics are crucial as histopathological type influences selection of treatment in lung cancer. The aim of this study was to evaluate real-world accuracy and use of immunohistochemical (IHC) staining in lung cancer diagnostics.

MATERIALS AND METHODS

The diagnosis and used IHC stains for small specimens with lung cancer on follow-up resection were retrospectively investigated for a 15-month period at two major sites in Sweden. Additionally, 10 pathologists individually suggested diagnostic IHC staining for 15 scanned bronchial and lung biopsies and cytological specimens.

RESULTS

In 16 (4.7%) of 338 lung cancer cases, a discordant diagnosis of potential clinical relevance was seen between a small specimen and the follow-up resection. In half of the cases, there was a different small specimen from the same investigational work-up with a concordant diagnosis. Diagnostic inaccuracy was often related to a squamous marker not included in the IHC panel (also seen for the scanned cases), the case being a neuroendocrine tumor, thyroid transcription factor-1 (TTF-1) expression in squamous cell carcinomas (with clone SPT24), or poor differentiation. IHC was used in about 95% of cases, with a higher number of stains in biopsies and in squamous cell carcinomas and especially neuroendocrine tumors. Pre-surgical transthoracic samples were more often diagnostic than bronchoscopic ones (72-85% vs. 9-53% for prevalent types).

CONCLUSIONS

Although a high overall diagnostic accuracy of small specimens was seen, small changes in routine practice (such as consequent inclusion of p40 and TTF-1 clone 8G7G3/1 in the IHC panel for non-small cell cancer with unclear morphology) may lead to improvement, while reducing the number of IHC stains would be preferable from a time and cost perspective.

Accuracy of fine-needle aspiration of lymph nodes: A cancer center's experience

INTRODUCTION

Lymph node fine needle aspiration (LN-FNA) is a minimally invasive method of evaluating lymphadenopathy. Nonetheless, its use is not widely accepted due to the lack of guidelines and a cytopathological categorisation that directly relates to management. We report our experience with LN FNA at a large Cancer Center in Latin America.

METHODS

We retrospectively collected cytological cases of lymph node FNA from the department of pathology at AC Camargo Cancer Center performed over a 2-year period. Data extracted included LN location, age, sex and final cytological diagnosis. Patients that had undergone neoadjuvant chemotherapy and/or cases for which the surgery specimen location was not clearly reported were excluded. For those cases with surgical reports, risk of malignancy was calculated for each diagnostic category, along with overall performance of cytology. False positive cases were reviewed to assess any possible misinterpretation or sampling errors.

RESULTS

A total of 1730 LN-FNA were distributed as follows: 62 (3.5%) non-diagnostic (ND); 1123 (64.9%) negative (NEG), 19 (1.1%) atypical (ATY), 53 (3.1%) suspicious for malignancy (SUS), and 473 (27.3%) positive (POS). Surgical reports were available for 560 cases (32.4%). Risk of malignancy (ROM) for each category was 33.3% for ND, 29.9% for NEG, 25% for ATY, 74.2% for SUS and 99.6% for POS. Overall sensitivity, specificity, negative predictive value (NPV) and positive predictive value (PPV) were 78.5%, 99.4%, 70.2% and 99.6%, respectively.

CONCLUSION

Lymph node FNA is a very specific and accurate exam, which is reliable in the detection of lymph node metastasis and other causes of lymphadenopathy.

Digital analysis of hormonal immunostaining in pituitary adenomas classified according to WHO 2017 criteria and correlation with preoperative laboratory findings

OBJECTIVE

The authors sought to evaluate clinical and laboratory data from pituitary adenoma (PA) patients with functioning PA (associated with acromegaly [n = 10] or Cushing disease [n = 10]) or nonfunctioning PA (NFPA; n = 10) that were classified according to 2017 WHO criteria (based on the expression of the transcription factors pituitary-specific positive transcription factor 1 [Pit-1], a transcription factor member of the T-box family [Tpit], and steroidogenic factor 1 [SF-1]) and to assess the immunostaining results for growth hormone (GH) and adrenocorticotropic hormone (ACTH) in the corresponding tumors.

METHODS

Clinical and laboratory data were collected retrospectively. The percentage of tumoral cells positive for Pit-1, Tpit, or SF-1 was assessed and ImageJ software was used to evaluate immunopositivity in PAs with 2 different antibodies against GH (primary antibody 1 [AbGH-1] and primary antibody 2 [AbGH-2]) and 2 different antibodies against ACTH (primary antibody 1 [AbACTH-1] and primary antibody 2 [AbACTH-2]).

RESULTS

Cells with positive Pit-1 staining were more frequently observed in lesions from patients with acromegaly (acromegaly group) than in lesions from patients with Cushing disease (Cushing group; p < 0.001) and those from patients with NFPA (NFPA group; p < 0.001). The percentage of Tpit-positive cells was higher in the Cushing group than in the acromegaly (p < 0.001) and NFPA (p < 0.001) groups. No difference was detected regarding SF-1 frequency among all groups (p = 0.855). In acromegalic individuals, GH immunostaining levels varied depending on the antibody employed, and only one of the antibodies (AbGH-2) yielded higher values in comparison with the values for NFPA patients (p < 0.001). For all of the antibodies employed, no significant correlations were detected between GH tissue expression and the laboratory data (serum GH vs AbGH-1, p = 0.933; serum GH vs AbGH-2, p = 0.853; serum insulin-like growth factor-1 [IGF-1] vs AbGH-1, p = 0.407; serum IGF-1 vs AbGH-2, p = 0.881). In the Cushing group data, both antibodies showed similar ACTH tissue expression, which was higher than that obtained in the NFPA group (p < 0.001). There were no significant associations between ACTH immunohistochemical findings and ACTH serum levels (serum ACTH vs AbACTH-1, p = 0.651; serum ACTH vs AbACTH-2, p = 0.987). However, ACTH immunostaining evaluated with AbACTH-1 showed a significant correlation with 24-hour urinary cortisol (24-hour cortisol vs AbACTH-1, p = 0.047; 24-hour cortisol vs AbACTH-2, p = 0.071).

CONCLUSIONS

Immunostaining for Pit-1 and Tpit accurately identified lesions associated with acromegaly and Cushing disease, respectively. Conversely, SF-1 did not differentiate NFPA from lesions of the other two groups. Regarding hormonal tissue detection, results of the current investigation indicate that different antibodies may lead not only to divergent immunohistochemical results but also to lack of correlation with laboratory findings. Finally, PA classification based on transcription factor expression (Pit-1, Tpit, and SF-1), as proposed by the 2017 WHO classification of pituitary tumors, may avoid the limitations of PA classification based solely on digital immunohistochemical detection of hormones.

Difficulties in diagnostics of lung tumours in biopsies: an interpathologist concordance study evaluating the international diagnostic guidelines

AIMS

Accurate and reliable diagnosis is essential for lung cancer treatment. The study aim was to investigate interpathologist diagnostic concordance for pulmonary tumours according to WHO diagnostic criteria.

METHODS

Fifty-two unselected lung and bronchial biopsies were diagnosed by a thoracic pathologist based on a broad spectrum of immunohistochemical (IHC) stainings, molecular data and clinical/radiological information. Slides stained with H&E, thyroid transcription factor-1 (TTF-1) clone SPT24 and p40 were scanned and provided digitally to 20 pathologists unaware of reference diagnoses. The pathologists independently diagnosed the cases and stated if further diagnostic markers were deemed necessary.

RESULTS

In 31 (60%) of the cases, ≥80% of the pathologists agreed with each other and with the reference diagnosis. Lower agreement was seen in non-small cell neuroendocrine tumours and in squamous cell carcinoma with diffuse TTF-1 positivity. Agreement with the reference diagnosis ranged from 26 to 45 (50%-87%) for the individual pathologists. The pathologists requested additional IHC staining in 15-44 (29%-85%) of the 52 cases. In nearly half (17 of 36) of the malignant cases, one or more pathologist advocated for a different final diagnosis than the reference without need of additional IHC markers, potentially leading to different clinical treatment.

CONCLUSIONS

Interpathologist diagnostic agreement is moderate for small unselected bronchial and lung biopsies based on a minimal panel of markers. Neuroendocrine morphology is sometimes missed and TTF-1 clone SPT24 should be interpreted with caution. Our results suggest an intensified education need for thoracic pathologists and a more generous use of diagnostic IHC markers.

Geospatial immune variability illuminates differential evolution of lung adenocarcinoma

Remarkable progress in molecular analyses has improved our understanding of the evolution of cancer cells toward immune escape1-5. However, the spatial configurations of immune and stromal cells, which may shed light on the evolution of immune escape across tumor geographical locations, remain unaddressed. We integrated multiregion exome and RNA-sequencing (RNA-seq) data with spatial histology mapped by deep learning in 100 patients with non-small cell lung cancer from the TRACERx cohort6. Cancer subclones derived from immune cold regions were more closely related in mutation space, diversifying more recently than subclones from immune hot regions. In TRACERx and in an independent multisample cohort of 970 patients with lung adenocarcinoma, tumors with more than one immune cold region had a higher risk of relapse, independently of tumor size, stage and number of samples per patient. In lung adenocarcinoma, but not lung squamous cell carcinoma, geometrical irregularity and complexity of the cancer-stromal cell interface significantly increased in tumor regions without disruption of antigen presentation. Decreased lymphocyte accumulation in adjacent stroma was observed in tumors with low clonal neoantigen burden. Collectively, immune geospatial variability elucidates tumor ecological constraints that may shape the emergence of immune-evading subclones and aggressive clinical phenotypes.

The value of desmosomal plaque-related markers to distinguish squamous cell carcinoma and adenocarcinoma of the lung

Background: An antibody panel is needed to definitively differentiate between adenocarcinoma (AC) and squamous cell carcinoma (SCC) in order to meet more stringent requirements for the histologic classification of lung cancers. Staining of desmosomal plaque-related proteins may be useful in the diagnosis of lung SCC.Materials and methods: We compared the usefulness of six conventional (CK5/6, p40, p63, CK7, TTF1, and Napsin A) and three novel (PKP1, KRT15, and DSG3) markers to distinguish between lung SCC and AC in 85 small biopsy specimens (41 ACs and 44 SCCs). Correlations were examined between expression of the markers and patients' histologic and clinical data.Results: The specificity for SCC of membrane staining for PKP1, KRT15, and DSG3 was 97.4%, 94.6%, and 100%, respectively, and it was 100% when the markers were used together and in combination with the conventional markers (AUCs of 0.7619 for Panel 1 SCC, 0.7375 for Panel 2 SCC, 0.8552 for Panel 1 AC, and 0.8088 for Panel 2 AC). In a stepwise multivariate logistic regression model, the combination of CK5/6, p63, and PKP1 in membrane was the optimal panel to differentiate between SCC and AC, with a percentage correct classification of 96.2% overall (94.6% of ACs and 97.6% of SCCs). PKP1 and DSG3 are related to the prognosis.Conclusions: PKP1, KRT15, and DSG3 are highly specific for SCC, but they were more useful to differentiate between SCC and AC when used together and in combination with conventional markers. PKP1 and DSG3 expressions may have prognostic value.

Simultaneous expression of TTF1 and GATA3 in a lung biopsy sample: confusion in diagnostic pathology

BACKGROUND

In daily work, pathologists often use TTF1 and GATA3 in the differential diagnosis of primary lung adenocarcinoma (TTF1+ GATA3-) and metastatic bladder cancer (or breast cancer) (TTF1- GATA3+). However, we encountered a small lung biopsy sample of TTF1+ GATA3+ (clinically suggesting both lung and bladder occupancy), and the dyeing results caused us great confusion; thus, we intended to determine the expressions of TTF1 and GATA3 in lung and bladder cancer by expanding the sample.

METHODS

The study included a complete case report and the tissue microarrays including pulmonary squamous cell carcinomas (n = 55), lung adenocarcinomas (n = 47), high-grade (n = 68) and low-grade (n = 43) urothelial carcinomas of the bladder. TTF1 and GATA3 immunohistochemical staining were performed on the tissue microarrays, and the relevant literature was retrieved.

RESULTS

Our staining results on tissue microarrays showed that TTF1 was expressed in pulmonary adenocarcinomas (44/47, 93.6%), squamous cell carcinomas (1/55, 1.8%), low-grade (1/43, 2.3%) and high-grade (2/68, 2.9%) urothelial carcinomas; GATA3 was only expressed in urothelial carcinomas of the bladder (high-grade: 48/68, 70.6%; low-grade: 42/43, 97.7%). Our literature search results showed that TTF1 could be expressed in a very small number of bladder urothelial carcinomas, and GATA3 could be expressed in a few primary lung squamous cell carcinomas and a very small number of primary lung adenocarcinomas.

CONCLUSIONS

TTF1 and GATA3 are good markers in the differential diagnosis of primary non-small cell lung cancer (GATA3-) and metastatic urothelial carcinoma of the bladder (GATA3+). However, pathologists should pay attention to a few special cases: lung cancer may express GATA3, and urothelial carcinoma may express TTF1. In these cases, some additional immunohistochemical markers, such as napsin A and URO III, should be added to assist the diagnosis.

[Immunophenotyping of lung tumors : An update]

The WHO Classification of Lung Tumors (2015) established the use of immunohistochemical stainings for resection specimens, however, detailed recommendations had been missing. Now, an international expert panel has summarized key questions for daily routine practice and provided recommendations to assist the community in the appropriate use of immunohistochemistry in this context. This article provides an overview of the most important aspects.

Practical Application of Lineage-Specific Immunohistochemistry Markers: Transcription Factors (Sometimes) Behaving Badly

CONTEXT.—

Transcription factors (TFs) are proteins that regulate gene expression and control RNA transcription from DNA. Lineage-specific TFs have increasingly been used by pathologists to determine tumor lineage, especially in the setting of metastatic tumors of unknown primary, among other uses. With experience gathered from its daily application and increasing pitfalls reported from immunohistochemical studies, these often-touted highly specific TFs are not as reliable as once thought.

OBJECTIVES.—

To summarize the established roles of many of the commonly used TFs in clinical practice and to discuss known and potential sources for error (eg, false-positivity from cross-reactivity, aberrant, and overlap "lineage-specific" expression) in their application and interpretation.

DATA SOURCES.—

Literature review and the authors' personal practice experience were used. Several examples selected from the University Health Network (Toronto, Ontario, Canada) are illustrated.

CONCLUSIONS.—

The application of TF diagnostic immunohistochemistry has enabled pathologists to better assess the lineage/origin of primary and metastatic tumors. However, the awareness of potential pitfalls is essential to avoid misdiagnosis.

Diagnostic Utility of Thyroid Transcription Factor-1 in Ovarian Carcinoma and Its Relationship With Clinicopathologic Prognostic Parameters

Although thyroid transcription factor-1 (TTF-1) is considered a relatively sensitive and specific marker for lung and thyroid neoplasms, it can occasionally be expressed in other tumors. Few immunohistochemical studies have been conducted on TTF-1 expression in ovarian carcinomas with discrepant results. To date, only 1 study compared different TTF-1 clones in ovarian carcinoma. This study is designed to evaluate the expression of TTF-1 clones in ovarian carcinomas and investigate TTF-1 association with clinicopathologic prognostic parameters. A retrospective immunohistochemical study was conducted on 62 primary ovarian carcinomas and 15 normal ovarian tissues using 2 clones of TTF-1 antibody (SPT24 and 8G7G3/1). Nuclear expression of SPT24 and 8G7G3/1 clones of TTF-1 was detected in 17.7% and 3.2% of ovarian carcinomas, respectively. Positive cytoplasmic immunostaining of clone SPT24 was detected in 1.6% of cases. In contrast, normal ovarian tissue showed negative expression of both clones. A highly significant difference was observed between both clones regarding their sensitivity in ovarian carcinomas (P=0.004). A significant inverse relationship was observed between TTF-1 (SPT24 clone) expression and tumor stage (P=0.022). TTF-1 expression is not exclusive to lung and thyroid tissue. It is expressed in ovarian carcinomas where clone SPT24 is more sensitive than clone 8G7G3/1. TTF-1 might be of diagnostic utility in evaluating neoplasms of unknown primary origin as well as adenocarcinomas involving the lung in patients with a history of a gynecologic malignancy. Moreover, TTF-1 expression might be a good prognostic factor in ovarian carcinoma.

The Incidence of Labelling of Non-Lung Adenocarcinomas With Antibodies Against TTF-1 and Diagnostic Implications

Thyroid transcription factor 1 (TTF-1) is an immunohistochemical marker in the identification of lung and thyroid tumors. However, positive labelling for TTF-1 can occur in tumors from other sites, and this can result in misdiagnosis if only a limited panel of antibodies is used. We assessed the frequency of expression of 3 TTF-1 antibody clones, namely, 8G7G3/1, SPT24, and SP141 on a tissue microarray of 104 colorectal cancer (CRC), and whole-tumor sections of 165 CRC with known microsatellite instability (MSI) status. We also analyzed the expression of TTF-1 in a tissue microarray of 112 prostatic adenocarcinomas. The association of TTF-1 expression with clinicopathologic parameters and patient survival was analyzed. Six of 104 (5.7%) primary colorectal carcinomas expressed TTF-1 with SPT24 and SP141 clones, whereas only 2 (2%) of these tumors labeled positive for TTF-1 with clone 8G7G3/1. A significant association of TTF-1 expression with younger age at diagnosis (P=0.001) was found, but not with stage, or survival. The SP141 clone also labelled 24/165 (14.5%) of 165 CRC with known MSI status. There was an association with younger age (P<0.001), but not with MSI status or survival. TTF-1 expression was found in 39/112 (34%) prostate adenocarcinomas with 6/112 (5.3%) labelling with clone 8G7G3/1, 26/112 (23%) with clone SP141, and 31/112 (28%) with clone SPT24. TTF-1 expression appeared to be associated with extracapsular extension (P=0.022) and with higher stage (P=0.039). Here too TTF-1 expression was not associated with survival. The mRNA expression of TTF-1 in these tumors was confirmed by RTPCR, indicating that this is not false-positive labelling. Depending on the clone used, TTF-1 expression can vary with the SP141 and SPT24 clones exhibiting higher incidence of labelling. Pathologists should be aware of the differences in performance profiles of the different TTF-1 clones in diagnostic practice.

Role of Immunocytochemistry in the Cytological Diagnosis of Pulmonary Tumors

Pulmonary cytology is a challenging diagnostic tool, and it is usually evaluated considering medical history and radiological findings in order to reach an accurate diagnosis. Since the majority of lung cancer patients have an advanced stage at diagnosis, a cytological specimen is frequently the only material available for diagnosis and further prognostic/predictive marker determination. Several types of specimens can be obtained from the respiratory system (including sputum, bronchoalveolar lavage, bronchial brushing, fine needle aspiration, and pleural fluid) with different technical preclinical management protocols and different diagnostic yields. Immunocytochemistry (ICC) has a pivotal role in the determination of diagnostic, prognostic, and predictive markers. Therefore, limited cytology samples are to be used with a cell-sparing approach, to allow both diagnostic ICC evaluation as well as predictive marker assessment by ICC or specific molecular assays. In this review, we describe the most common ICC markers used for the diagnosis and prognostic/predictive characterization of thoracic tumors in different cytological specimens.

TTF1 Expression in Pulmonary Metastatic Rectal Adenocarcinoma

Thyroid transcription factor (TTF-1) is a tissue-specific nuclear transcription factor expressed developing thyroid, respiratory epithelium, and diencephalon. TTF-1 is thought to be expressed specifically in most thyroid tumors and in a significant subset of pulmonary neoplasms. However, recent studies on its expression in extrapulmonary carcinomas have demonstrated that TTF-1 is not as specific for lung and thyroid carcinomas as was previously thought: positivity of this marker can be observed, although much less frequently, in some carcinomas arising in other organs, such as the ovaries, endometrium, colon, and breast, as well as in some tumors of the central nervous system. Case reports of patients with TTF-1-positive colon adenocarcinoma are present in medical literature, but there are only a few cases of TTF-1-positive rectal adenocarcinoma. We present the case of a patient with rectal adenocarcinoma with lung metastasis found to be TTF-1-positive on immunohistochemistry. A review of the available literature is also included.

Thyroid hormone: a resurgent treatment for an emergent concern

The story of thyroid hormone in human physiology is one of mixed emotions. Studying past literature on its use leads one to believe that it serves only a few functions in a handful of diseases. In reality, the pathophysiological role of thyroid hormone is an uncharted expanse. Over the past few decades, research on thyroid hormone has been understandably monopolized by studies of hypo- and hyperthyroidism and cancers. However, in our focused pursuit, we have neglected to observe its role in systems that are not so easily relatable. Recent evidence in lung disease suggests that the thyroid hormone is capable of preserving mitochondria in an indirect manner. This is an exciting revelation given the profound implications of mitochondrial dysfunction in several lung diseases. When paired with known links between thyroid hormone and fibrotic pathways, thyroid hormone-based therapies become more enticing for research. In this article, we inspect the sudden awareness surrounding thyroid hormone and discuss why it is of paramount importance that further studies scrutinize the potential of thyroid hormone, and/or thyromimetics, as therapies for lung diseases.

"Man in Istanbul" Lesions of the Urinary Tract (Known Entities in an Unusual Context): Melanoma, Carcinoid Tumors, Epithelioid Angiosarcoma

Certain tumors are more difficult to recognize when they present in an unusual location. Within the urinary tract, primary melanomas, carcinoid tumors, or epithelioid angiosarcoma could present diagnostic challenges due to their infrequent occurrence. This article emphasizes the clinical and histopathologic features of these entities and their differential diagnoses including the immunophenotype and their prognoses.

Diagnostic and Predictive Immunohistochemistry for Non-Small Cell Lung Carcinomas

Non-small cell lung carcinoma (NSCLC) accounts for significant morbidity and mortality worldwide, with most patients diagnosed at advanced stages and managed increasingly with targeted therapies and immunotherapy. In this review, we discuss diagnostic and predictive immunohistochemical markers in NSCLC, one of the most common tumors encountered in surgical pathology. We highlight 2 emerging diagnostic markers: nuclear protein in testis (NUT) for NUT carcinoma; SMARCA4 for SMARCA4-deficient thoracic tumors. Given their highly aggressive behavior, proper recognition facilitates optimal management. For patients with advanced NSCLCs, we discuss the utility and limitations of immunohistochemistry (IHC) for the "must-test" predictive biomarkers: anaplastic lymphoma kinase, ROS1, programmed cell death protein 1, and epidermal growth factor receptor. IHC using mutant-specific BRAF V600E, RET, pan-TRK, and LKB1 antibodies can be orthogonal tools for screening or confirmation of molecular events. ERBB2 and MET alterations include both activating mutations and gene amplifications, detection of which relies on molecular methods with a minimal role for IHC in NSCLC. IHC sits at the intersection of an integrated surgical pathology and molecular diagnostic practice, serves as a powerful functional surrogate for molecular testing, and is an indispensable tool of precision medicine in the care of lung cancer patients.

Comparison of Three Different TTF-1 Clones in Resected Primary Lung Cancer and Epithelial Pulmonary Metastases

OBJECTIVES

Immunohistochemical staining against thyroid transcription factor 1 (TTF-1) is often used to distinguish lung adenocarcinoma from squamous cell carcinoma and pulmonary metastasis.

METHODS

TTF-1 expression was examined using the antibody clones 8G7G3/1, SPT24, and SP141 on tissue microarrays from 665 cases of resected lung cancers and 428 pulmonary metastases.

RESULTS

Most lung adenocarcinomas, 89%, 93%, and 93%, were positive with TTF-1 clones 8G7G3/1, SPT24, and SP141, respectively. The corresponding figures for lung squamous cell carcinomas were 0%, 6%, and 8%. In total, five (2%), 19 (7%), and 21 (8%) of the pulmonary metastases from colorectal adenocarcinomas were positive with clones 8G7G3/1, SPT24, and SP141, respectively. Other TTF-1-positive pulmonary metastases (n = 8) were thyroid, urothelial, pancreatic, small bowel, and cervix carcinomas.

CONCLUSIONS

TTF-1 expression in lung cancer and pulmonary metastases differs between clones, with 8G7G3/1 being more specific but less sensitive compared with SPT24 and SP141.

Expression of TTF-1 in breast cancer independently of ER expression: A case report and pathogenic implications

Thyroid Transcription Factor 1 (TTF-1) is often used for the immunohistochemical evaluation of lung cancers, as a significant proportion of these cancers are positive while other adenocarcinomas are usually negative. Breast cancers are known to express TTF-1 only in a small minority of cases but this may be problematic when this staining is used for its differential diagnosis from lung cancer. We present a case of ER-positive breast cancer in 30% of tumor cells that was also TTF-1 positive in some areas of the primary tumor but lost ER expression completely in the metastatic recurrence site while retaining TTF-1 positivity. Additionally, a PTEN mutation was present on genomic evaluation of the primary tumor. Diagnostic, pathogenic and therapeutic implications of these findings are discussed.

Acute appendicitis caused by metastatic adenocarcinoma from the lung: a case report

Background

Appendiceal metastasis from lung cancer is rare. However, it often causes acute appendicitis that requires emergency surgery. We herein report a thought-provoking case of appendiceal metastasis from lung cancer.

Case presentation

A 71-year-old man was diagnosed with advanced lung cancer with multiple metastases and underwent chemotherapy. One month later, he developed acute appendicitis, and laparoscopic appendectomy was promptly performed. A swollen appendix and pus collection were observed during surgery. Histological analysis revealed an invasive adenocarcinoma in the appendix that infiltrated the mucosal, submucosal, and muscular layers. Positive immunostaining of thyroid transcription factor 1 indicated appendiceal metastasis of pulmonary adenocarcinoma, not a primary appendiceal malignancy. The postoperative course was uneventful, and the patient’s pulmonary internist resumed continuous chemotherapy after surgery.

Conclusions

Although appendiceal metastasis from pulmonary adenocarcinoma is rare, it often results in acute appendicitis. Optimal therapy including emergency surgery should be performed without hesitation so that chemotherapy can be resumed as soon as possible.

Immunohistochemistry in Diagnostic Parathyroid Pathology

Pathologists are usually readily able to diagnose parathyroid tissues and diseases, particularly when they have knowledge of the clinical information, laboratory findings, and radiographic imaging studies. However, the identification of parathyroid tissue or lesions can be difficult in small biopsies, ectopic locations, supranumerary glands, and in some oxyphil/oncocytic lesions. Widely available immunohistochemical studies such as chromogranin-A, synaptophysin, keratin, parathyroid hormone, thyroglobulin, and thyroid transcription factor-1 can help in difficult cases. One of the most difficult diagnostic aspects faced by the pathologist in evaluating parathyroid is distinguishing between parathyroid adenoma, particularly atypical adenoma, and parathyroid carcinoma. Many markers have and continue to be evaluated for diagnostic utility, and are even beginning to be studied for prognostic utility. Single immunohistochemical markers such as parafibromin and Ki-67 are among the most studied and most utilized, but many additional markers have and continue to be evaluated such as galectin-3, PGP9.5, Rb, bcl2, p27, hTERT, mdm2, and APC. Although not widely available in many laboratories, a panel of immunohistochemical markers may prove most useful as an adjunct in the evaluation of challenging parathyroid tumors.

Update on Immunohistochemistry for the Diagnosis of Lung Cancer

Immunohistochemistry is a widely available technique that is less challenging and can provide clinically meaningful results quickly and cost-efficiently in comparison with other techniques. In addition, immunohistochemistry allows for the evaluation of cellular localization of proteins in the context of tumor structure. In an era of precision medicine, pathologists are required to classify lung cancer into specific subtypes and assess biomarkers relevant to molecular-targeted therapies. This review summarizes the hot topics of immunohistochemistry in lung cancer, including (i) adenocarcinoma vs squamous cell carcinoma; (ii) neuroendocrine markers; (iii) ALK, ROS1, and EGFR; (iv) PD-L1 (CD274); (v) lung carcinoma vs malignant mesothelioma; and (vi) NUT carcinoma. Major pitfalls in evaluating immunohistochemical results are also described.

Biomarkers in Urachal Cancer and Adenocarcinomas in the Bladder: A Comprehensive Review Supplemented by Own Data

Urachal cancer (UrC) is a rare but aggressive cancer. Due to overlapping histomorphology, discrimination of urachal from primary bladder adenocarcinomas (PBAC) and adenocarcinomas secondarily involving the bladder (particularly colorectal adenocarcinomas, CRC) can be challenging. Therefore, we aimed to give an overview of helpful (immunohistochemical) biomarkers and clinicopathological factors in addition to survival analyses and included institutional data from 12 urachal adenocarcinomas. A PubMed search yielded 319 suitable studies since 1930 in the English literature with 1984 cases of UrC including 1834 adenocarcinomas (92%) and 150 nonadenocarcinomas (8%). UrC was more common in men (63%), showed a median age at diagnosis of 50.8 years and a median tumor size of 6.0 cm. No associations were noted for overall survival and progression-free survival (PFS) and clinicopathological factors beside a favorable PFS in male patients (p = 0.047). The immunohistochemical markers found to be potentially helpful in the differential diagnostic situation are AMACR and CK34βE12 (UrC versus CRC and PBAC), CK7, β-Catenin and CD15 (UrC and PBAC versus CRC), and CEA and GATA3 (UrC and CRC versus PBAC). Serum markers like CEA, CA19-9 and CA125 might additionally be useful in the follow-up and monitoring of UrC.

Classification of pulmonary neuroendocrine tumors: new insights

Neuroendocrine tumors of the lung (Lu-NETs) embrace a heterogeneous family of neoplasms classified into four histological variants, namely typical carcinoid (TC), atypical carcinoid (AC), large cell neuroendocrine carcinoma (LCNEC) and small cell lung carcinoma (SCLC). Defining criteria on resection specimens include mitotic count in 2 mm2 and the presence or absence of necrosis, alongside a constellation of cytological and histological traits including cell size and shape, nuclear features and overall architecture. Clinically, TC are low-grade malignant tumors, AC intermediate-grade malignant tumors and SCLC/LCNEC high-grade malignant full-blown carcinomas with no significant differences in survival between them. Homologous tumors arise in the thymus that occasionally have some difficulties in differentiating from the lung counterparts when presented with large unresectable or metastatic lesions. Immunohistochemistry (IHC) helps refine NE diagnosis at various anatomical sites, particularly on small-sized tissue material, in which only TC and small cell carcinoma categories can be recognized easily on hematoxylin & eosin stain, while AC and LCNEC can only be suggested on such material. The Ki-67 labeling index effectively separates carcinoids from small cell carcinoma and may prove useful for the clinical management of a metastatic disease to help the therapeutic decision-making process. Although carcinoids and high-grade neuroendocrine carcinomas in the lung and elsewhere make up separate tumor categories on molecular grounds, emerging data supports the concept of secondary high-grade NETs arising in the preexisting carcinoids, whose clinical and biological relevance will have to be placed into the proper context for the optimal management of these patients. In this review, we will discuss the selected, recent literature with a focus on current issues regarding Lu-NET nosology, i.e., classification, derivation and tumor evolution.

Thyroid transcription factor-1 expression in invasive and non-invasive urothelial carcinomas

BACKGROUND

Thyroid transcription factor-1 (TTF-1) has been considered a sensitive marker for thyroid and lung tumors. Recent data have shown that a wide range of neoplasms may express TTF-1.

CASE SERIES

We performed an immunohistochemical study in a case series of 42 urothelial carcinomas (UCs) on tissue microarrays sections, in order to investigate how often UCs express the TTF-1 protein and the diagnostic utility of this marker. In addition, we sought to determine by immunohistochemistry if there is an association between TTF-1 expression and the expression of specific basal-like or luminal markers. Five out of the 42 cases (11.9 %) were positive for TTF-1. Three positive tumors concerned non-invasive papillary UCs. There was no association between TTF-1 expression and tumor grade (χ², p =0.419), stage (χ², p =0.550) or cytokeratin 5/6 (χ², p =0.330), cytokeratin 20 (χ², p =0.995) and estrogen receptors expression (χ², p =0.268).

CONCLUSIONS

UCs may show TTF-1 expression and pathologists should be aware of this phenomenon in order to avoid misdiagnosis, notably in metastatic disease. HIPPOKRATIA 2017, 21(3): 154-157.

Targeted sequencing may facilitate differential diagnostics of pulmonary tumours: a case series

Background

Histopathological diagnosis is important for prognostication and choice of treatment in patients with cancer in the lung. Metastases to the lungs are common and need to be distinguished from primary lung cancer. Furthermore, cases with synchronous or metachronous primary lung cancers (although infrequent) are often handled differently than cases with lung cancer with intrapulmonary metastasis or relapse, respectively. In some cases, morphology and immunohistochemical staining is not sufficient for certain diagnosis.

Methods

The present study included six cases where molecular genetic analysis in form of pyrosequencing or targeted next-generation sequencing was of value for certain diagnosis of selected tumours in the lung.

Results

Two of the included cases were rare metastases to the lung; colorectal cancer with IHC profile consistent with primary lung cancer and malignant adenomyoepithelioma of the breast, respectively, where molecular genetic analysis was of aid for proving the relationship to the primary tumour. The other four cases were multiple lung adenocarcinomas where molecular genetic analysis was of aid to distinguish between intrapulmonary metastasis and synchronous tumour.

Conclusions

Comparison of molecular genetic profile may be an important tool for determination of relationship between tumours in some situations and should always be considered in unclear cases. Further studies on concordance and discordance of molecular genetic profiles between spatially or temporally different tumours with common origin may be helpful for improved diagnostics of pulmonary tumours.

Diagnostic Immunohistochemistry: What Can Go Wrong and How to Prevent It

CONTEXT

-There are a number of critical factors that can lead to incorrect results if the diagnostic pathologist performing immunohistochemistry is unaware of, or not vigilant about, their influence.

OBJECTIVE

-To highlight 3 arenas in which errors may be introduced.

DATA SOURCES

-For choosing the correct primary antibody, selection of the most appropriate antibodies for a given clinical application can be aided by obtaining information from the vendor; however, this can yield incomplete information. There are a number of online databases that have comparisons of antibodies from different vendors, particularly with respect to their use and properties. Reading the published literature can assist in this process, particularly with respect to determining antibody sensitivity and specificity, but it is a daunting task to keep up with all of the immunohistochemistry-related papers published. Finally, Web sites of a number of quality assurance organizations are accessible and can provide a wealth of information comparing the "real world" performance characteristics of different antibodies to the same target protein. False-positive signals can result from a number of factors, including the use of inappropriately high antibody concentration, and "pseudospecific" signal that is in the wrong compartment of the cell. False-negative signal can result from factors such as use of a nonoptimized epitope retrieval method. It is critical that epitope retrieval methods be optimized for each antibody employed in the laboratory.

CONCLUSIONS

-By paying attention to these potential problems, the "black box" of diagnostic immunohistochemistry can be made more transparent.

Thyroid transcription factor-1 distinguishes subependymal giant cell astrocytoma from its mimics and supports its cell origin from the progenitor cells in the medial ganglionic eminence

Subependymal giant cell astrocytoma is a benign brain tumor mostly associated with tuberous sclerosis complex. However, it may be misinterpreted as other high-grade brain tumors due to the presence of large tumor cells with conspicuous pleomorphism and occasional atypical features, such as tumor necrosis and endothelial proliferation. In this study, we first investigated thyroid transcription factor-1 (TTF-1) expression in a large series of subependymal giant cell astrocytomas and other histologic and locational mimics to validate the diagnostic utility of this marker. We then examined TTF-1 expression in non-neoplastic brain tissue to determine the cell origin of subependymal giant cell astrocytoma. Twenty-four subependymal giant cell astrocytoma specimens were subjected to tissue microarray construction. For comparison, a selection of tumors, including histologic mimics (21 gemistocytic astrocytomas and 24 gangliogliomas), tumors predominantly occurring at the ventricular system (50 ependymomas, 19 neurocytomas, and 7 subependymomas), and 134 astrocytomas (3 pleomorphic xanthoastrocytomas, 45 diffuse astrocytomas, 46 anaplastic astrocytomas, and 40 glioblastomas) were used. Immunohistochemical stain for TTF-1 was positive in all 24 subependymal giant cell astrocytomas, whereas negative in all astrocytomas, gangliogliomas, ependymomas, and subependymomas. Neurocytomas were positive for TTF-1 in 4/19 (21%) of cases using clone 8G7G3/1 and in 9/19 (47%) of cases using clone SPT24. In the three fetal brains that we examined, TTF-1 expression was seen in the medial ganglionic eminence, a transient fetal structure between the caudate nucleus and the thalami. There was no BRAF^V600E mutation identified by direct sequencing in the 20 subependymal giant cell astrocytomas that we studied. In conclusion, TTF-1 is a useful marker in distinguishing subependymal giant cell astrocytoma from its mimics. Expression of TTF-1 in the fetal medial ganglionic eminence indicates that subependymal giant cell astrocytoma may originate from the progenitor cells in this region.