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MTE 02.01 Appropriate and Optimized Handling of Surgically Resected Specimens
ABSTRACTS MEET THE EXPERT SESSIONS MTE 01.01 Management of Small Nodules Detected by CT Screening; A Surgeon’s Perspective J. Nakajima Department of Thoracic Surgery, The University of Tokyo Hospital, Tokyo/JP Along with the prevalence of screening with computed tomography (CT), small pulmonary ground-glass density nodules (GGN) have been detected more frequently. A GGN is a round area of increased pulmonary opacity with intact bronchial and vascular structures. GGNs showing no or slow growth during follow-up period are most likely to be “early” adenocarcinomas showing lepidic pattern pathologically. There are three problems in diagnostics and therapeutics of GGNs. First, should they be treated or not? They might not change for years. We might take a risk of postoperative comorbidity for a harmless disease. Some large prospective observational studies on these pulmonary small GGNs have been performed: From clinical practice performed in these clinical trials, We found that 5-30% of GGN were resected during the observation period, because of the increased size or appearance of solid part in the GGN. Almost all of the pathologies of the resected GGN were adenocarcinomas. Partsolid GGNs were more likely to be diagnosed as invasive adenocarcinomas than pure GGNs. That is, we can correctly diagnose small pulmonary GGNs as adenocarcinomas when their CT images are changed. However, it is still unclear whether surgical intervention will contribute to increased survival from lung cancer. Second, how to detect pulmonary GGOs at surgery, if they are located deep in lung parenchyma? GGNs are difficult to identify even by bimanual palpation through open thoracotomy, because they are as soft as lung parenchyma if they show pure GGN appearance. Preoperative marking of these GGN is mandatory to ensure a definite resection. Many methods for detecting small pulmonary nodules have been developed: Preoperative hookwire placement under CT observation has been most widely performed. The punctured hook wire with thread can easily be identified that excisional biopsy may be done through thoracoscopy. However, arterial air embolism is reported to be occasionally associated with the placement of hookwire which can cause lethal results. Instead, dye marking, or fiducial placement through bronchoscopy has been revived to replace the hookwire method. We have recently developed Virtual-assisted lung mapping (VAL-MAP), a relatively brand-new lung marking technique using dye multiple dye markings through bronchoscope. Before bronchoscopy, we create a virtual 3-D bronchoscope map with CT and plan where to mark. Multiple dye markings enable us to determine the extent of resection with safe margin from the tumor. Actually safer margin from the tumor was shown to be secured by this method. Third, how to determine the extent of pulmonary resection for these small GGNs? Still there is no evidence other than lobectomy and lymph node dissection for early non-small cell lung cancer (NSCLC), clinical trials have been performed to prove feasibility and no-inferiority of sublobar resections (wedge resection and segmentectomy) for small NSCLC, especially those 2cm in diameter. In Japan and USA, prospective randomized studies are on the way to obtain more reliable evidence. In conclusion, management of small pulmonary nodules suspected of an early carcinoma includes the determination of operative indication, detection technique of the tumor, aiming to safer and effective treatment of these tumors. Keywords: ground glass density nodules, surgical indication, tumor detection
MTE 02.01 Appropriate and Optimized Handling of Surgically Resected Specimens E. Thunnissen Pathology Department, VU University Medical Center, Amsterdam/NL Guidelines for gross handling are to our knowledge not formulated in the literature. However, the College of American Physicians (CAP) formulates “required elements” for synoptic reporting regarding gross handling of pulmonary resection specimen, mainly focusing at pathology staging, but does not include grossing requirements.1 The current practice of handling resection specimen in Amsterdam involves interaction with surgeons for submission of specimen. This includes i) Information about pretreatment, type of surgery (including pneumonectomy, (sleeve) lobectomy, segmentectomy, and wedge resection), site of specimen, number of tumors; ii) eventual frozen section for diagnosis and/or resection margin; iii) eventual additional information of specimen e.g. adhesion from parietal pleura, additional wedge from adjacent lobe adhesion; iv) agreement on marking the ‘cold’ side from bronchial resection slice [see note A]; For the pathologist, the order of handling the fresh specimen is i) to maintain the 3 dimensional orientation of the resection specimen along the axial, coronal and sagital planes; ii) to describe outer surface of specimen; iii) to photograph overview from medial and lateral side; iv) to cut slice of bronchial resection margin; v) to cut tumor, preferably in axial plane for sampling of normal lung tissue and tumor for research (culture, freezing) [see notes B and C]; vi) to perform perfusion fixation of peripheral lung; vii) and to immerse whole specimen in large volume neutral buffered formalin. After 24 hours, fixation the specimen is handled in the following way: i) Intrapulmonary lymph nodes are separately embedded ii) the specimen is further cut in slices along the same plane as done for the fresh specimen; iii) the slices are positioned in order of cutting, numbered and photographs taken; iv) description of specimen with tumor characteristics: focality (size; vital, necrosis, fibrosis), distance from tumor to margins recorded (to bronchial resection, pleura). If tumor is present in sequential slices, cumulative tumor thickness is measured; v) other characteristics are described (mucus in dilated bronchi; post-obstruction pneumonia; emphysema etc.) vi) sample representative blocks from tumor, normal tissue, resection margin arteria pulmonalis, and nearest point(s) to pleura for embedding in paraffin; vii) annotate the location of sampled blocks on a copy of the gross slices. After a few days during first microscopy, the 3 dimensional orientation can be reconstructed and the pTNM parameters extracted from the gross and microscopic information. If needed, additional samples can be taken [see note C]. Classification is performed for most parts according to the WHO2, except for not reproducible categories and immature concepts. Pathology reporting contains pTNMR [see note D]. The pathology report is usually made within 9 working days, except if bony structures are included, then the process will contain an additional week. If postoperative radiotherapy is indicated, the 3 dimensional approach also supports determination of the position(s) for radiation, especially if clips were not placed during surgery. Notes: A, As for frozen section, the cold side of the bronchial resection margin [i.e. the side distant from the patient] is placed downwards on the frozen template, the first cut frozen section sections [representing the nearest to the patient tissue margins (warm side)] are sequentially placed on the microscope slide. In case of uneven surface maximally 6 sections, until complete circumference is achieved, are placed on two microscopic slides, and stained for H&E. The bronchial resection margin is considered tumor-free, if the complete circumferential margin does not contain tumor. If needed, in this
Journal of Thoracic Oncology
Vol. 12 No. 11S2: S1633-S1655
S1634 judgement sequential complementarity of the 6 sections may be taken into account. The sleeve lobectomy has two resection margins: one on the cold side and the other on the warm side (larger bronchial diameter). These are separately examined. If only tumor cells are found in lymph vessels (but no direct tumor spread), this will be reported, but not considered necessary for indication of additional bronchial margin, as lymphangitic distribution is associated with N2 disease.3,4 B, As it has been proven that loose tissue fragments are caused by gross cutting5,6, the knife is rinsed and quickly wiped after each slice that happens to contain tumor. STAS is considered to be an artifact and in contrast to CAP and WHO classification, is not considered as part of the tumor. C, In Pancoast tumor, the ‘en-bloc resection’ incorporates extrapulmonary structures directly invaded by tumor, usually ribs. During the fresh handling, the thoracic wall is cut from the lung. Subsequently, both cut surfaces are colored to denote the artifical edges. Bone requires after fixation extra time for decalcification, extending reporting with one week. D, The R ¼ defined as follows: R0 ¼ free resection margins; R1 ¼ microscopic margins not free; R2 ¼ margins not free during gross examination/surgery. Peripheral wedge resections contain a parenchymal margin, which is represented by the tissue at the staple line(s). The staples are cut from the specimen, but not further examined. Adjacent tissue is sampled for microscopic examination. If this section does not contain tumor, the margin is free (R0). However, if this contains tumor, an educated guess is reasonable, encompassing the amount of tumor compared to the other sections, and the estimation of the staple thickness (±2mm). References: 1. College of American Pathologists. Cancer Protocol Templates. Lung cancer vs4. http://www.cap.org/web/oracle/webcenter/portalapp/ pagehierarchy/Cancer_protocol_templates.jspx?_afrLoop¼44552922521771 0#!%40%40%3F_afrLoop%3D445529225217710%26_adf.ctrl-state%3D xmm1doio_4. 2. Travis W., Brambilla E, Burke AP, Marx A, Nicholson AG. WHO Classification of Tumors of the Lung, Pleura, Thymus and Heart. 4th ed. (Travis W., Brambilla E, Burke AP, Marx A, Nicholson AG, eds.). Lyon: IARC; 2015. 3. Thunnissen FBJM, den Bakker MA. Implications of frozen section analyses from bronchial resection margins in NSCLC. Histopathology. 2005;47(6):638-640. http://dx.doi.org/10.1111/ j.1365-2559.2005.02263.x. 4. Vallières E, Van Houtte P, Travis WD, Rami-Porta R, Goldstraw P. Carcinoma in situ at the bronchial resection margin: a review. J Thorac Oncol. 2011;6(10):1617-1623. http://dx.doi. org/10.1097/JTO.0b013e31822ae082. 5. Blaauwgeers H, Flieder D, Warth A, et al. A Prospective Study of Loose Tissue Fragments in NoneSmall Cell Lung Cancer Resection Specimens. Am J Surg Pathol. June 2017:1. http://dx.doi.org/10.1097/PAS.0000000000000889. 6. Thunnissen E, Blaauwgeers HJLG, de Cuba EM V, et al. Ex Vivo Artifacts and Histopathologic Pitfalls in the Lung. Arch Pathol Lab Med. 2016;140(3):212-220. http://dx.doi.org/10.5858/arpa.2015-0292-OA.
MTE 02.02 Appropriate and Optimized Handling of Biopsy or Cytology Specimens M. Mino-Kenudson Pathology, Massachusetts General Hospital & Harvard Medical School, Boston, MA/US The recent advance in personalized medicine along with minimally invasive endoscopic techniques in the field of lung cancer has brought significant complexities to handling of tissue samples. Due to the histology-directed therapy, additional stains are frequently required to achieve accurate histologic subtyping on small biopsy and cytology samples. It is recommended that epidermal growth factor receptor (EGFR), anaplastic lymphoma kinase (ALK) and ROS1 testing be performed for patients with advanced non-squamous small cell lung cancer (NSCLC) in a reflex manner. In addition, multiplex assays, including next generation sequencing (NGS), are increasingly being used for detection of the molecular targets. Furthermore, immunohistochemistry (IHC) for programmed death ligand-1 (PD-L1) is now routinely
Journal of Thoracic Oncology
Vol. 12 No. 11S2
performed in NSCLCs with wild type EGFR and ALK to determine eligibility for PD-1/PD-L1 blockade.1 In most advanced NSCLC patients, a small biopsy or cytology specimen is often the only sample available for the diagnosis and biomarker analyses. Thus, appropriate tissue acquisition, processing and management for multiple tests are crucial and are best achieved by the interaction of all physicians involved in the patient care.2,3 Tissue Acquisition: All the necessary work-up is usually performed on a small biopsy or cytology specimen taken from a patient with advanced disease, tissue sampling should be aimed at obtaining the largest yield of tumor in the safest and least invasive manner.4 Tissue Processing: Appropriate pre-analytic tissue handling is one of the keys to successful implementation of IHC-based and molecular assays in general.3,5 An ischemia time from tissue procurement to the initiation of fixation should be short (as short as possible), and biopsies should immediately be immersed in fixative for 6-48 hours. Of note, multiple tissue fragments in a biopsy sample (obtained from one lesion) may be submitted in a few tissue cassettes to avoid tissue exhaustion that is not infrequently seen when the single available tissue block is cut and used for multiple purposes. Neutral buffered formalin is historically the preferred and most common fixative used in the practice of histopathology.6 Consequently, the majority of pathology laboratories typically perform the initial validation of IHC and molecular protocols on FFPE tissue. Decalcifying solutions used for bony specimens vary in their effects on retention and integrity of nucleic acids and proteins. Thus, results of IHC on decalcified specimens are unpredictable because of wide variations in specimen types and sizes, fixation time, and the particular solution(s) used.7 Similarly, alcohol fixation used for cytology specimens, including alcohol-fixed cell blocks, decreases IHC accuracy by causing loss or decrease of immunogenicity when IHC protocols optimized with FFPE tissue samples are used.8 For molecular assays, samples fixed with acidic solutions (including decalcifying salutations) and heavy metal fixatives are not recommended due to further degradation of nuclear acid and heavy metals hampering PCR reaction, respectively.9 Thus, tissue sampling of a bone metastasis for this purpose should be avoided, if possible. In case the bone metastasis is the only accessible lesion for sampling, the pathologist may try to separate a soft tissue component submitted in the formalin. Up to 40% of advanced NSCLC patients are diagnosed by cytology alone. Cytology smears, cytospins and liquid-based cytology (LBC), processed from fine needle aspiration (FNA) or other modalities, are typically treated with alcohol-based solution or sprays devoid of exposure to formalin that leads to fragmentation of nuclear acids, thus often contain tumor cells with intact nucleic acid ideal for molecular testing. However, formalin-fixed paraffin-embedded (FFPE) cell blocks processed from the residual material from FNA or LBC or body fluid are the preferred samples for ancillary testing in many laboratories, since they can be handled in the same way as biopsy/resection specimens.2 Tissue Management: To maximize small samples, the number of times when the tissue block needs to be cut for diagnosis, IHC and molecular testing should be minimized. It is because a decent amount of tissue is cut and wasted for trimming of the block at each round of sectioning. Thus, extra sections may be cut up front at the first cutting for diagnostic histology sections. Many pathology laboratories already have protocols in place per local requirements under close supervision by pathologists. It is also important that the pathologist is in close communication with oncologists and proceduralists to ensure that relevant clinical information is provided before sectioning is done. Diagnostic work-up between the lesion with high probability of a lung primary and a possible metastasis, and that between primary diagnosis and progression/recurrence after targeted therapy are often different, thus lack of the critical information may lead to unnecessary IHC. Last, but not least, the pathologist needs to evaluate tissue adequacy (tumor cellularity, the presence or absence of necrosis and tissue quality, etc.) before submitting samples for molecular testing. References: 1. NCCN Clinical Practice Guidelines in Oncology: Non-Small Cell Lung Cancer. Version 8.2017 e July 14, 2017. 2. Bubendorf L, Lantuejoul S, de
MTE 02.01 Appropriate and Optimized Handling of Surgically Resected Specimens E. Thunnissen Pathology Department, VU University Medical Center, Amsterdam/NL Guidelines for gross handling are to our knowledge not formulated in the literature. However, the College of American Physicians (CAP) formulates “required elements” for synoptic reporting regarding gross handling of pulmonary resection specimen, mainly focusing at pathology staging, but does not include grossing requirements.1 The current practice of handling resection specimen in Amsterdam involves interaction with surgeons for submission of specimen. This includes i) Information about pretreatment, type of surgery (including pneumonectomy, (sleeve) lobectomy, segmentectomy, and wedge resection), site of specimen, number of tumors; ii) eventual frozen section for diagnosis and/or resection margin; iii) eventual additional information of specimen e.g. adhesion from parietal pleura, additional wedge from adjacent lobe adhesion; iv) agreement on marking the ‘cold’ side from bronchial resection slice [see note A]; For the pathologist, the order of handling the fresh specimen is i) to maintain the 3 dimensional orientation of the resection specimen along the axial, coronal and sagital planes; ii) to describe outer surface of specimen; iii) to photograph overview from medial and lateral side; iv) to cut slice of bronchial resection margin; v) to cut tumor, preferably in axial plane for sampling of normal lung tissue and tumor for research (culture, freezing) [see notes B and C]; vi) to perform perfusion fixation of peripheral lung; vii) and to immerse whole specimen in large volume neutral buffered formalin. After 24 hours, fixation the specimen is handled in the following way: i) Intrapulmonary lymph nodes are separately embedded ii) the specimen is further cut in slices along the same plane as done for the fresh specimen; iii) the slices are positioned in order of cutting, numbered and photographs taken; iv) description of specimen with tumor characteristics: focality (size; vital, necrosis, fibrosis), distance from tumor to margins recorded (to bronchial resection, pleura). If tumor is present in sequential slices, cumulative tumor thickness is measured; v) other characteristics are described (mucus in dilated bronchi; post-obstruction pneumonia; emphysema etc.) vi) sample representative blocks from tumor, normal tissue, resection margin arteria pulmonalis, and nearest point(s) to pleura for embedding in paraffin; vii) annotate the location of sampled blocks on a copy of the gross slices. After a few days during first microscopy, the 3 dimensional orientation can be reconstructed and the pTNM parameters extracted from the gross and microscopic information. If needed, additional samples can be taken [see note C]. Classification is performed for most parts according to the WHO2, except for not reproducible categories and immature concepts. Pathology reporting contains pTNMR [see note D]. The pathology report is usually made within 9 working days, except if bony structures are included, then the process will contain an additional week. If postoperative radiotherapy is indicated, the 3 dimensional approach also supports determination of the position(s) for radiation, especially if clips were not placed during surgery. Notes: A, As for frozen section, the cold side of the bronchial resection margin [i.e. the side distant from the patient] is placed downwards on the frozen template, the first cut frozen section sections [representing the nearest to the patient tissue margins (warm side)] are sequentially placed on the microscope slide. In case of uneven surface maximally 6 sections, until complete circumference is achieved, are placed on two microscopic slides, and stained for H&E. The bronchial resection margin is considered tumor-free, if the complete circumferential margin does not contain tumor. If needed, in this
Journal of Thoracic Oncology
Vol. 12 No. 11S2: S1633-S1655
S1634 judgement sequential complementarity of the 6 sections may be taken into account. The sleeve lobectomy has two resection margins: one on the cold side and the other on the warm side (larger bronchial diameter). These are separately examined. If only tumor cells are found in lymph vessels (but no direct tumor spread), this will be reported, but not considered necessary for indication of additional bronchial margin, as lymphangitic distribution is associated with N2 disease.3,4 B, As it has been proven that loose tissue fragments are caused by gross cutting5,6, the knife is rinsed and quickly wiped after each slice that happens to contain tumor. STAS is considered to be an artifact and in contrast to CAP and WHO classification, is not considered as part of the tumor. C, In Pancoast tumor, the ‘en-bloc resection’ incorporates extrapulmonary structures directly invaded by tumor, usually ribs. During the fresh handling, the thoracic wall is cut from the lung. Subsequently, both cut surfaces are colored to denote the artifical edges. Bone requires after fixation extra time for decalcification, extending reporting with one week. D, The R ¼ defined as follows: R0 ¼ free resection margins; R1 ¼ microscopic margins not free; R2 ¼ margins not free during gross examination/surgery. Peripheral wedge resections contain a parenchymal margin, which is represented by the tissue at the staple line(s). The staples are cut from the specimen, but not further examined. Adjacent tissue is sampled for microscopic examination. If this section does not contain tumor, the margin is free (R0). However, if this contains tumor, an educated guess is reasonable, encompassing the amount of tumor compared to the other sections, and the estimation of the staple thickness (±2mm). References: 1. College of American Pathologists. Cancer Protocol Templates. Lung cancer vs4. http://www.cap.org/web/oracle/webcenter/portalapp/ pagehierarchy/Cancer_protocol_templates.jspx?_afrLoop¼44552922521771 0#!%40%40%3F_afrLoop%3D445529225217710%26_adf.ctrl-state%3D xmm1doio_4. 2. Travis W., Brambilla E, Burke AP, Marx A, Nicholson AG. WHO Classification of Tumors of the Lung, Pleura, Thymus and Heart. 4th ed. (Travis W., Brambilla E, Burke AP, Marx A, Nicholson AG, eds.). Lyon: IARC; 2015. 3. Thunnissen FBJM, den Bakker MA. Implications of frozen section analyses from bronchial resection margins in NSCLC. Histopathology. 2005;47(6):638-640. http://dx.doi.org/10.1111/ j.1365-2559.2005.02263.x. 4. Vallières E, Van Houtte P, Travis WD, Rami-Porta R, Goldstraw P. Carcinoma in situ at the bronchial resection margin: a review. J Thorac Oncol. 2011;6(10):1617-1623. http://dx.doi. org/10.1097/JTO.0b013e31822ae082. 5. Blaauwgeers H, Flieder D, Warth A, et al. A Prospective Study of Loose Tissue Fragments in NoneSmall Cell Lung Cancer Resection Specimens. Am J Surg Pathol. June 2017:1. http://dx.doi.org/10.1097/PAS.0000000000000889. 6. Thunnissen E, Blaauwgeers HJLG, de Cuba EM V, et al. Ex Vivo Artifacts and Histopathologic Pitfalls in the Lung. Arch Pathol Lab Med. 2016;140(3):212-220. http://dx.doi.org/10.5858/arpa.2015-0292-OA.
MTE 02.02 Appropriate and Optimized Handling of Biopsy or Cytology Specimens M. Mino-Kenudson Pathology, Massachusetts General Hospital & Harvard Medical School, Boston, MA/US The recent advance in personalized medicine along with minimally invasive endoscopic techniques in the field of lung cancer has brought significant complexities to handling of tissue samples. Due to the histology-directed therapy, additional stains are frequently required to achieve accurate histologic subtyping on small biopsy and cytology samples. It is recommended that epidermal growth factor receptor (EGFR), anaplastic lymphoma kinase (ALK) and ROS1 testing be performed for patients with advanced non-squamous small cell lung cancer (NSCLC) in a reflex manner. In addition, multiplex assays, including next generation sequencing (NGS), are increasingly being used for detection of the molecular targets. Furthermore, immunohistochemistry (IHC) for programmed death ligand-1 (PD-L1) is now routinely
Journal of Thoracic Oncology
Vol. 12 No. 11S2
performed in NSCLCs with wild type EGFR and ALK to determine eligibility for PD-1/PD-L1 blockade.1 In most advanced NSCLC patients, a small biopsy or cytology specimen is often the only sample available for the diagnosis and biomarker analyses. Thus, appropriate tissue acquisition, processing and management for multiple tests are crucial and are best achieved by the interaction of all physicians involved in the patient care.2,3 Tissue Acquisition: All the necessary work-up is usually performed on a small biopsy or cytology specimen taken from a patient with advanced disease, tissue sampling should be aimed at obtaining the largest yield of tumor in the safest and least invasive manner.4 Tissue Processing: Appropriate pre-analytic tissue handling is one of the keys to successful implementation of IHC-based and molecular assays in general.3,5 An ischemia time from tissue procurement to the initiation of fixation should be short (as short as possible), and biopsies should immediately be immersed in fixative for 6-48 hours. Of note, multiple tissue fragments in a biopsy sample (obtained from one lesion) may be submitted in a few tissue cassettes to avoid tissue exhaustion that is not infrequently seen when the single available tissue block is cut and used for multiple purposes. Neutral buffered formalin is historically the preferred and most common fixative used in the practice of histopathology.6 Consequently, the majority of pathology laboratories typically perform the initial validation of IHC and molecular protocols on FFPE tissue. Decalcifying solutions used for bony specimens vary in their effects on retention and integrity of nucleic acids and proteins. Thus, results of IHC on decalcified specimens are unpredictable because of wide variations in specimen types and sizes, fixation time, and the particular solution(s) used.7 Similarly, alcohol fixation used for cytology specimens, including alcohol-fixed cell blocks, decreases IHC accuracy by causing loss or decrease of immunogenicity when IHC protocols optimized with FFPE tissue samples are used.8 For molecular assays, samples fixed with acidic solutions (including decalcifying salutations) and heavy metal fixatives are not recommended due to further degradation of nuclear acid and heavy metals hampering PCR reaction, respectively.9 Thus, tissue sampling of a bone metastasis for this purpose should be avoided, if possible. In case the bone metastasis is the only accessible lesion for sampling, the pathologist may try to separate a soft tissue component submitted in the formalin. Up to 40% of advanced NSCLC patients are diagnosed by cytology alone. Cytology smears, cytospins and liquid-based cytology (LBC), processed from fine needle aspiration (FNA) or other modalities, are typically treated with alcohol-based solution or sprays devoid of exposure to formalin that leads to fragmentation of nuclear acids, thus often contain tumor cells with intact nucleic acid ideal for molecular testing. However, formalin-fixed paraffin-embedded (FFPE) cell blocks processed from the residual material from FNA or LBC or body fluid are the preferred samples for ancillary testing in many laboratories, since they can be handled in the same way as biopsy/resection specimens.2 Tissue Management: To maximize small samples, the number of times when the tissue block needs to be cut for diagnosis, IHC and molecular testing should be minimized. It is because a decent amount of tissue is cut and wasted for trimming of the block at each round of sectioning. Thus, extra sections may be cut up front at the first cutting for diagnostic histology sections. Many pathology laboratories already have protocols in place per local requirements under close supervision by pathologists. It is also important that the pathologist is in close communication with oncologists and proceduralists to ensure that relevant clinical information is provided before sectioning is done. Diagnostic work-up between the lesion with high probability of a lung primary and a possible metastasis, and that between primary diagnosis and progression/recurrence after targeted therapy are often different, thus lack of the critical information may lead to unnecessary IHC. Last, but not least, the pathologist needs to evaluate tissue adequacy (tumor cellularity, the presence or absence of necrosis and tissue quality, etc.) before submitting samples for molecular testing. References: 1. NCCN Clinical Practice Guidelines in Oncology: Non-Small Cell Lung Cancer. Version 8.2017 e July 14, 2017. 2. Bubendorf L, Lantuejoul S, de