An immunohistochemical analysis of a newly developed, mouse monoclonal p40 (BC28) antibody in lung, bladder, skin, breast, prostate, and head and neck cancers

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.

A Case of Biphenotypic Adnexal Carcinoma With Bowenoid and Basaloid Features: Focus on the Expression of SOX9 and Wnt Signaling Pathway Molecules, Including CDX2

ABSTRACT

An 87-year-old woman presented with a pedunculated nodule of 1.2 × 1.2 × 0.6 cm on her left cheek. Microscopic examination of the lesion revealed bowenoid and rosette-like basaloid components, resembling Bowen disease and neuroendocrine carcinoma, respectively. Immunohistochemically, both components were positive for Wnt signaling pathway molecules-nuclear/cytoplasmic beta-catenin, lymphoid enhancer binding factor 1 (LEF1), and caudal type homeobox 2 (CDX2)-and the adnexal marker SRY-box transcription factor 9 (SOX9). Unlike neuroendocrine tumors and basal cell carcinomas, the basaloid component in the present case was negative for chromogranin A, INSM1, synaptophysin, and p40. Previously reported cases of similar CDX2-positive lesions were diagnosed as squamous cell carcinoma with enteric adenocarcinomatous differentiation and basaloid cutaneous carcinoma with a primitive cytomorphology. However, the lesion in the present case was simultaneously positive for SOX9, indicating adnexal differentiation. In particular, the expression of multiple Wnt signaling pathway molecules indicates follicular differentiation despite the absence of morphological follicular features, such as shadow cells. Moreover, shared immunopositivity for SOX9, CDX2, nuclear/cytoplasmic beta-catenin, and LEF1 by both bowenoid and basaloid components indicated that the bowenoid component did not represent Bowen disease but a part of the adnexal tumor, and that the basaloid component was not a tumor-to-tumor metastasis. After complete excision, no recurrence has been observed for 5 months. The findings of the present case expand the histological spectrum of cutaneous adnexal tumors with follicular immunophenotypic differentiation.

Evaluation of Heterogeneous Nuclear Ribonucleoprotein D Expression as a Diagnostic Marker for Oral Squamous Cell Carcinoma

The heterogeneous nuclear ribonucleoprotein D (hnRNPD) serves as a prognostic marker for oral squamous cell carcinoma (OSCC). We evaluated the diagnostic potential of hnRNPD to differentiate between OSCC and normal mucosa. Immunohistochemistry for hnRNPD and a routinely used diagnostic marker deltaNp63 (p40) was performed in 32 normal mucosae and 46 OSCC specimens. Subsequently, receiver-operating characteristic analysis was performed to evaluate the diagnostic potential of hnRNPD in comparison to that of p40. Immunostaining for p40 and hnRNPD was observed in 39 (84.78%) and 38 (82.60%) cases, respectively, in OSCC specimens. The poorly differentiated squamous cell carcinoma displayed 100% (eight cases) immunoreactivity for hnRNPD as compared to 87.5% (seven cases) for p40. Nuclear staining of p40 and hnRNPD was observed in all OSCC specimens. p40 staining was restricted to basal cells, whereas both basal and para-basal cells displayed hnRNPD staining in OSCC specimens. Areas under the curve for p40 and hnRNPD were 0.86 and 0.87, respectively. p40 and hnRNPD showed equal sensitivities (80.95%). However, hnRNPD displayed marginally higher (88.23%) specificity for tumor cells as compared to that of p40 (85.29%). Conclusion: In addition to being a well-established prognostic marker, hnRNPD can serve as a diagnostic marker for OSCC.

The foggy world(s) of p63 isoform regulation in normal cells and cancer

The p53 family member p63 exists as two major protein variants (TAp63 and ΔNp63) with distinct expression patterns and functional properties. Whilst downstream target genes of p63 have been studied intensively, how p63 variants are themselves controlled has been relatively neglected. Here, we review advances in understanding ΔNp63 and TAp63 regulation, highlighting their distinct pathways. TAp63 has roles in senescence and metabolism, and in germ cell genome maintenance, where it is activated post-transcriptionally by phosphorylation cascades after DNA damage. The function and regulation of TAp63 in mesenchymal and haematopoietic cells is less clear but may involve epigenetic control through DNA methylation. ΔNp63 functions to maintain stem/progenitor cells in various epithelia and is overexpressed in squamous and certain other cancers. ΔNp63 is transcriptionally regulated through multiple enhancers in concert with chromatin modifying proteins. Many signalling pathways including growth factors, morphogens, inflammation, and the extracellular matrix influence ΔNp63 levels, with inconsistent results reported. There is also evidence for reciprocal regulation, including ΔNp63 activating its own transcription. ΔNp63 is downregulated during cell differentiation through transcriptional regulation, while post-transcriptional events cause proteasomal degradation. Throughout the review, we identify knowledge gaps and highlight discordances, providing potential explanations including cell-context and cell-matrix interactions. Identifying individual p63 variants has roles in differential diagnosis and prognosis, and understanding their regulation suggests clinically approved agents for targeting p63 that may be useful combination therapies for selected cancer patients. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Validation of Superiority of p40 over p63 in Differentiating Squamous Cell Carcinoma and Adenocarcinoma Lung

In this era of targeted therapy, it is important to distinguish the various subtypes of nonsmall cell lung carcinoma (NSCC). Diagnosis based on morphology alone is challenging in poorly differentiated carcinomas and core biopsies. Immunohistochemistry (IHC) helps in specifying the lineage for the subtype of NSCC. Till date, p63 is the most frequently used and sensitive marker for squamous cell carcinoma (SQCC). However, it is not specific and stains a subset of adenocarcinoma (ADC). Thus, a more reliable and specific marker is required for the diagnosis of SQCC.

The objective of the study was to validate the diagnostic utility of p40 over p63 in differentiating pulmonary SQCC from ADC and NSCC-not otherwise specified (NOS).

A total of 123 cases of NSCC were initially reviewed and subtyped blinded to the results of IHC. This was followed by a review of IHC slides which included p63, p40, thyroid transcription factor 1, Napsin-A, cytokeratin (CK) 5/6, and CK7.

There were 64 ADC, 19 SQCC, and 40 NSCC-NOS. IHC helped to confirm the morphological diagnosis in 62/64 ADCs and19/19 SQCCs. IHC classified the cases of NSCC-NOS into NSCC favoring ADC – 12 cases, NSCC favoring SQCC – 10 cases, and NSCC favoring AD-SQCC – 4 cases. Both p63 and p40 showed near equal sensitivity for SQCC (100% and 97%, respectively), whereas p63 showed far lower specificity when compared to p40 (51.3% vs. 100%).

The present study confirms and validates that p40 is equally sensitive but highly specific than p63 in detecting SQCC. Hence, we recommend the routine use of p40 instead of p63 for the definite categorization of NSCC of the lung.

Pattern of Invasion in Human Pancreatic Cancer Organoids Is Associated with Loss of SMAD4 and Clinical Outcome

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignancy characterized by extensive local invasion and systemic spread. In this study, we employed a three-dimensional organoid model of human pancreatic cancer to characterize the molecular alterations critical for invasion. Time-lapse microscopy was used to observe invasion in organoids from 25 surgically resected human PDAC samples in collagen I. Subsequent lentiviral modification and small-molecule inhibitors were used to investigate the molecular programs underlying invasion in PDAC organoids. When cultured in collagen I, PDAC organoids exhibited two distinct, morphologically defined invasive phenotypes, mesenchymal and collective. Each individual PDAC gave rise to organoids with a predominant phenotype, and PDAC that generated organoids with predominantly mesenchymal invasion showed a worse prognosis. Collective invasion predominated in organoids from cancers with somatic mutations in the driver gene SMAD4 (or its signaling partner TGFBR2). Reexpression of SMAD4 abrogated the collective invasion phenotype in SMAD4-mutant PDAC organoids, indicating that SMAD4 loss is required for collective invasion in PDAC organoids. Surprisingly, invasion in passaged SMAD4-mutant PDAC organoids required exogenous TGFβ, suggesting that invasion in SMAD4-mutant organoids is mediated through noncanonical TGFβ signaling. The Rho-like GTPases RAC1 and CDC42 acted as potential mediators of TGFβ-stimulated invasion in SMAD4-mutant PDAC organoids, as inhibition of these GTPases suppressed collective invasion in our model. These data suggest that PDAC utilizes different invasion programs depending on SMAD4 status, with collective invasion uniquely present in PDAC with SMAD4 loss. SIGNIFICANCE: Organoid models of PDAC highlight the importance of SMAD4 loss in invasion, demonstrating that invasion programs in SMAD4-mutant and SMAD4 wild-type tumors are different in both morphology and molecular mechanism.

Head-to-Head Comparison of p63 and p40 in Non-Neuroendocrine Carcinomas of the Tubal Gut

OBJECTIVES.

With targeted agents, characterizing carcinomas of the gastrointestinal (GI) tract has become more important. We aim to determine the usefulness of p40 in classifying GI tract carcinomas.

METHODS.

Seventy-five GI carcinomas including 28 squamous cell carcinomas (SCC), 2 adenosquamous carcinomas (ASCA), 21 poorly differentiated carcinomas (PDCA), and 24 adenocarcinomas (AdCA; control group) were stained for p40, p63, and CK5/6. Tumors were scored from 0 to 5 based on extent of staining and marked as positive (score >2) or negative.

RESULTS.

p63 was positive in 100% of SCC/ASCA and 12.5% of AdCA. p40 was positive in 92.5% of SCC/ASCA and 4.1% of AdCA. In the PDCA subset, a panel including p63, p40, and MOC31 was the best way to accurately classify most cases.

CONCLUSIONS.

p63 and CK5/6 are more sensitive but less specific than p40 for SCC/ASCA in GI carcinomas. In PDCA, a panel approach including p63, CK5/6, and p40 may be best in classifying these cases.

p63 Is a Promising Marker in the Diagnosis of Unusual Skin Cancer

Skin cancer is the most common type of cancer worldwide. Ozone depletion and climate changes might cause a further increase in the incidence rate in the future. Although the early detection of skin cancer enables it to be treated successfully, some tumours can evolve and become more aggressive, especially in the case of melanoma. Therefore, good diagnostic and prognostic markers are needed to ensure correct detection and treatment. Transcription factor p63, a member of the p53 family of proteins, plays an essential role in the development of stratified epithelia such as skin. In this paper, we conduct a comprehensive review of p63 expression in different types of skin cancer and discuss its possible use in the diagnosis and prognosis of cutaneous tumours.

Focal positivity of immunohistochemical markers for pulmonary squamous cell carcinoma in primary pulmonary choriocarcinoma: A histopathological study

Cytokeratin 5/6 (CK5/6), p63, and p40 are commonly used as immunohistochemical markers for squamous cell carcinoma (SqCC) of the lung. To elucidate their positivity in primary pulmonary choriocarcinoma (PPC), the present study examined 4 PPCs, including 1 surgically removed PPC and 3 postmortem PPCs. All PPCs consisted of nested cytotrophoblastic tumor cells and occasional syncytiotrophoblastic tumor cells although 1 surgically removed PPC was markedly affected by pre-operative therapy-associated necrosis and 3 postmortem PPCs coexisted with adenocarcinoma. In 1 surgical case, a pre-operative biopsy specimen of PPC contained a few polygonal tumor cells, which mimicked SqCC and exhibited focal p40+ features. Nuclear p63+ and p40+ features of cytotrophoblast-like polygonal tumor cells were focally observed in 3 PPCs (75%) and 2 PPCs (50%), respectively. CK5/6+ trophoblastic tumor cells were focally identified in 1 PPC. Additionally, in 2 other PPCs, CK5/6+ tumor cells were scattered in choriocarcinomatous areas, but possible intermingling of CK5/6+ adenocarcinoma cells could not be ruled out. The results emphasized that PPCs could mimic SqCC morphologically and immunohistochemically, although PPC was an extremely rare neoplasm. Surgical pathologists should be aware of this diagnostic pitfall when encountering a few squamous marker-positive polygonal tumor cells within hemorrhagic necrotic biopsy specimens from lung tumors.

p40 Immunohistochemistry Is an Excellent Marker in Primary Lung Squamous Cell Carcinoma

BACKGROUND

Lung cancer is the third most common cancer worldwide. With major advances in the molecular testing of lung cancers and the introduction of targeted therapies, the distinction between adenocarcinoma and squamous cell carcinoma as well as pathologic subtyping has become important. Recent studies showed that p40 is highly specific for squamous and basal cells and is superior to p63 for diagnosing lung squamous cell carcinoma. The aim of this study was to evaluate the use of p40 immunohistochemical stain in the diagnosis of non-small cell lung carcinoma and its potential to replace current p63 antibody as the best immunohistochemical squamous marker.

METHODS

Seventy formalin-fixed paraffin-embedded cases previously diagnosed as primary lung squamous cell carcinoma (n = 35) and lung adenocarcinoma (n = 35) from January 2008 to December 2016 were retrieved. The results of tumour cell immunoreactivity for p40 and p63 antibodies in lung squamous cell carcinoma and lung adenocarcinoma were compared.

RESULTS

p40 was expressed in 27 cases of lung squamous cell carcinoma (77.1%). All cases of lung adenocarcinoma (35/35, 100%) were negative for p40. p63 expression was positive in 30 cases of lung squamous cell carcinoma (85.7%) and 13 cases of lung adenocarcinoma (37.1%). Reactivity for both p40 and p63 in lung squamous cell carcinoma was strong and diffuse, whereas variable reactivity was observed in lung adenocarcinoma.

CONCLUSIONS

p40 is an excellent marker for distinguishing lung squamous cell carcinoma from adenocarcinoma, and p40 expression is equivalent to p63 expression in lung squamous cell carcinoma.

Technical note: p40 antibody as a replacement for p63 antibody in bovine mammary immunohistochemistry

Tumor protein 63 (p63) is a nuclear antigen found in basal epithelial cells. To date, 10 isoforms of p63 have been identified, falling into 2 major groups identified by presence or absence of an N-terminal transactivation domain (TAp63 and ΔNp63, respectively). Literature suggests that ΔNp63 is the predominant form expressed in basal epithelial cells and myoepithelial cells (MYEC). The mouse anti-p63 antibody, clone 4B1E12, has been used as a specific nuclear marker for bovine MYEC. Unfortunately, this antibody is no longer commercially available. A new mouse monoclonal antibody, clone BC28, specific to ΔNp63 (designated p40) has been developed. We hypothesized that the p40 antibody would be an appropriate substitution as a MYEC and epithelial basal cell marker. An array of archived formalin-fixed, paraffin-embedded bovine tissues were subjected to immunohistochemical staining for either p40 or p63, with a subset being dual stained for direct comparison. Positive staining for p40 and p63 was observed in serial sections of mammary, skin, rumen, salivary gland, ureter, and bladder. As predicted, negative staining for p40 and p63 was observed in testis and intestine. Dual staining for p40 and p63 in calf mammary (n = 4), lactating mammary (n = 4), rumen (n = 4), and skin (n = 4) showed nearly 100% agreement. Thus, we established that the mouse monoclonal antibody, clone BC28, is a suitable replacement for anti-p63, clone 4B1E12, as a marker of MYEC and basal epithelial cells in bovine tissues.

p40 in Conjunction With CK20 and E-Cadherin Distinguishes Primary Adnexal Neoplasms of the Skin

Although basal cell carcinomas (BCC) show typical histomorphologic features, they sometimes remain difficult in distinction from benign adnexal skin tumors of follicular origin like trichoepithelioma (TE) or trichoblastoma (TB). Consequently, an immunohistochemical marker panel separating described entities would be helpful in clinical routine. Thus, we stained 22 skin lesions (BCC, TE, and TB) against β-catenin, CK20, E-cadherin, p40, and p63. The staining pattern was described and quantified using an immunohistochemical score. Although p40 and p63 revealed a strong staining intensity of all skin lesions without distinction between BCC and benign lesions (P=1.000), established Merkel cell marker CK20 illustrated a loss of staining in BCC compared with TE and TB (P=0.007). In contrast, BCC exhibited an increased expression of E-cadherin in relation to TE and TB (P=0.009). Single application of CK20 or E-cadherin could predict diagnosis of BCC in 81.8% or 72.7%, respectively. Combining consecutive staining of E-cadherin and CK20 could even enhance specificity toward diagnosis of TE or TB. Hence, findings of our study imply that sequential staining of CK20 and E-cadherin prevents false-positive classification of BCC. Furthermore, our study demonstrated that p40 exhibits the same staining pattern in BCC, TE, and TB. Therefore, p40 might replace p63 equivalently establishing diagnosis of primary adnexal neoplasms of the skin in the form of BCC as well as benign adnexal tumors. As a result, the depicted immunohistochemical marker panel may be applied for adnexal skin neoplasms as a diagnostic adjunct especially in surgically challenging body regions.

P40 Immunostain Does Not Outperform p63 as a Myoepithelial Cell Marker in the Daily Practice of Breast Pathology

P40 antibody has been shown to be a more specific squamous and basal cell marker compared with p63. As detection of myoepithelial cells (MECs) plays a critical role in breast pathology, and the fact that p40 targets an isoform of p63, this study was designed to compare these antibodies in a variety of lesions, especially those with an sclerotic stroma and carcinoma in situ. All studied lesions were selected from the daily cases of the 3 authors and stained with p63, p40, and calponin immunohistochemical stains. Thirty-four cases (and 19 internal controls) were included. Seventy percent constituted sclerotic lesions (12 cases) and ductal carcinoma in situ (12 cases). P40 and p63 stained all lesions and showed a similar patchy staining pattern in 50% of ductal carcinoma in situ and sclerotic lesions. Compared with internal controls, p40 and p63 demonstrated decreased staining intensity in up to 70% and 8% of all cases, respectively, with no cross-reactivity with mesenchymal cells and minor cross-reactivity with epithelial cells. In our study, p40 did not outperform p63 as a MEC marker. p40 showed a decreased intensity in a higher number of cases (P<0.0001). In our opinion, p63 continues to be the best nuclear marker for the detection of MECs in the daily practice of breast pathology.

Squamous and Neuroendocrine Specific Immunohistochemical Markers in Head and Neck Squamous Cell Carcinoma: A Tissue Microarray Study

The performance characteristics of neuroendocrine-specific and squamous-specific immunohistochemical markers in head and neck squamous cell carcinomas (SCC), in particular in oropharyngeal tumors in this era of human papillomavirus (HPV)-induced cases, are not well-established. The differential diagnosis for poorly differentiated SCCs, for nonkeratinizing oropharyngeal SCCs, and for other specific SCC variants such as basaloid SCC and undifferentiated (or lymphoepithelial-like) carcinomas includes neuroendocrine carcinomas. Given that neuroendocrine carcinomas of the head and neck are aggressive regardless of HPV status, separating them from SCC is critically important. In this study, we examined the neuroendocrine markers CD56, synaptophysin, and chromogranin-A along with the squamous markers p40 and cytokeratin 5/6 in a large tissue microarray cohort of oral, oropharyngeal, laryngeal, and hypopharyngeal SCCs with known HPV results by RNA in situ hybridization for the oropharyngeal tumors. Results were stratified by site and specific SCC variant. The neuroendocrine stains were rarely expressed in SCC (<1% overall) with CD56 the least, and chromogranin-A the most, specific markers. Further, p40 and cytokeratin 5/6 were very consistently expressed in all head and neck SCC (>98% overall), including very strong, consistent staining in oropharyngeal HPV-related nonkeratinizing SCC. Undifferentiated (or lymphoepithelial-like) carcinomas of the oropharynx are more frequently p40 or cytokeratin 5/6 negative or show only weak or focal expression. In summary, markers of neuroendocrine and squamous differentiation show very high specificity and sensitivity, respectively, across the different types of head and neck SCC.

TERT promoter mutation status in sarcomatoid urothelial carcinomas of the upper urinary tract

AIM

To determine TERT promoter mutation status as well as the expression of PAX8, GATA3, p63, p40, p53 and uroplakin III in 17 patients with the upper urinary tract sarcomatoid urothelial carcinoma.

METHODS & RESULTS

 TERT C228T mutations were found in six of 17 cases (35%). p53 was expressed in 77% of these tumors. PAX8, GATA3, p40 and uroplakin III are less frequently expressed. Lymph node metastases were present in ten cases (59%). Eight patients (47%), including all three patients with TERT mutation, died of cancer within 2 years after surgery.

CONCLUSION

Sarcomatoid carcinoma of the upper urinary tract is an aggressive tumor and the presence of TERT mutation may portend poor prognosis.

Urothelial carcinoma with squamous differentiation--the pathologists׳ perspective

Squamous differentiation is the most common variant histology in urothelial carcinoma and may have effects on clinical outcome. Inconsistencies in reporting variant histologies in urothelial carcinoma are well documented. Immunohistochemical and molecular markers may help identify tumors with squamous differentiation beyond light microscopy.

p40 as a Basal Cell Marker in the Diagnosis of Prostate Glandular Proliferations: A Comparative Immunohistochemical Study with 34betaE12

Immunohistochemistry is important for the accurate diagnosis of basal cells in atypical glandular proliferations of the prostate. p40, an isoform of p63, may be an adjunct to a marker panel in this setting. Biopsies of 68 patients were analyzed by immunohistochemistry using antibodies to 34betaE12 and p40. Basal cell staining was classified as negative, partial (<60%), or diffuse (≥60%); irregular staining was defined as discordant staining patterns. In acinar proliferations (N = 41), partial staining for both markers was seen in 42%, and diffuse staining in 46% of reactive cases. An irregular reactivity was noted in one case only (2%). Finally, these lesions were signed out as benign. Acinar proliferations negative for both markers and limited amount of glands (≤4) were termed atypical small acinar proliferations (ASAP). Out of six PIN lesions two cases showed partial, three cases showed diffuse reactivity for both markers, and one case was stained irregular. All cases diagnosed as prostate carcinomas (N = 20) had no evidence of basal cell staining for neither of the markers. p40 expression is closely correlated to 34betaE12 with respect to demonstration of basal cells of prostate glands and may provide further information on the dignity of glandular proliferations of the prostate.

Cytomorphology of sebaceous carcinoma with analysis of p40 antibody expression

BACKGROUND

Sebaceous carcinomas (SBCs) are aggressive tumors with the potential to cause great morbidity and mortality. Poorly-differentiated tumors may at times pose challenges for the correct diagnosis. p40, a new antibody that targets a short isoform of p63 has been shown as a promising squamous cell marker. In this study, we sought to evaluate cytomorphological features of SBC and p40 expression analysis.

METHODS

A total of 29 previously diagnosed cases of SBCs including fine-needle aspirates and histopathology specimens from various sites were reviewed and studied for p40 expression. p40 nuclear expression was semi-quantitatively assessed. Adequate positive and negative controls of non-small cell lung carcinoma were taken for comparison. Expression pattern of normal sebaceous glands was also analyzed.

RESULTS

Of the 29 cases, 13 (44.8%) were from the periocular region. The most common extraocular site was parotid gland. Morphologically tumors were categorized into well- and poorly-differentiated varieties based on extent of sebaceous differentiation. p40 positivity was seen in all cases of cytology aspirates and histology sections with similar intensity. No difference in percentage positivity of cells was recorded in well- and poorly-differentiated tumors.

CONCLUSION

p40 can be a valuable marker when evaluating tumors with possible sebaceous differentiation. Although p40 expression in SBCs is not as useful for the differential diagnosis that includes poorly-differentiated squamous cell carcinoma, this study, for the first time in the literature, highlights an important observation that p40 can be utilized as a marker for sebaceous lineage.

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

Context

Immunohistochemistry has become an indispensable ancillary tool for the accurate classification of pleuropulmonary and mediastinal neoplasms necessary for therapeutic decisions and predicting prognostic outcome in the era of personalized medicine. 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, authors' research data, and personal practice experience.

Conclusions

This review article has shown 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. The discovery of new mutation-specific antibodies identifying a subset of specific gene-arranged lung tumors provides a promising alternative and cost-effective approach to molecular testing. Knowing the utilities and pitfalls of each tumor-associated biomarker is essential to avoiding potential diagnostic errors.