Small Biopsy Specimens Research Articles

Characteristic Clinicopathological Features of Secondary Extramammary Paget Disease With Underlying Anorectal Adenocarcinoma: Evenly Circumferential Perianal Distribution, Fibroepithelioma of Pinkus-like Changes, and Subepidermal Mucin Deposits Without Invasive Tumor Cells.

This study aimed to identify the clinical and histopathological characteristics of secondary extramammary Paget disease (EMPD) with underlying anorectal adenocarcinoma so as to differentiate it from primary cutaneous EMPD. Seventeen and 8 cases of primary and secondary EMPD with anorectal adenocarcinoma, respectively, were retrieved from the pathology archive and the clinical and histopathological features reviewed. The tumor samples from 21 cases were totally resected specimens, whereas 3 and 1 of secondary and primary cases were punch biopsied, respectively. All 8 (100%) cases of secondary EMPD presented evenly distributed perianal lesions. By contrast, 4 of 17 (23.5%) primary EMPD cases had perianal skin lesions and displayed an uneven, asymmetrical distribution around the anus. Fibroepithelioma of Pinkus-like changes and subepidermal mucin deposits with no or few invasive tumor cells were observed in 6 (75%) and 3 (37.5%) of the 8 secondary EMPD cases, respectively, although 3 secondary case samples were small biopsy specimens. Both the histopathological changes were not observed in any of the 17 primary EMPD cases. Evenly circumferential perianal distribution, fibroepithelioma of Pinkus-like changes, and subepidermal mucin deposits without invasive tumor cells were characteristic to cases of secondary EMPD with anorectal adenocarcinoma. These clinicopathological features could be used to differentiate between secondary and primary EMPD.

Correlation between cytological and histopathological diagnosis of non-small cell lung cancer and accuracy of cytology in the diagnosis of lung cancer

Background/Aim. Lung cancer is one of the most com-mon cancer types worldwide. More than 70% of patients are diagnosed with lung cancer in the advanced stages of the disease, with limited therapeutic options based on cytological and histopathological material. The value of cytology in diagnosing and subtyping non-small cell lung cancer (NSCLC) is very important for modern personalized therapies. The aim of this study was to find out the concordance between cytological and histopathological diagnosis of NSCLC and the accuracy, sensitivity, specificity, and the positive and negative predictive value of cytology in diagnosing lung cancer. Methods. A two-year retrospective study included 169 patients with cytological diagnosis of NSCLC, who, at the same time, had small biopsy and surgical specimens for histopathological diagnoses confirmation that were compared with cytological one. Histopathological diagnosis on surgical specimens was the golden standard for evaluation concordance to the cytological diagnosis of NSCLC and evaluation accuracy, specificity, sensitivity, and the positive and negative prognostic value of cytology as a diagnostic method for detecting lung cancer. Results. This study included 129 (76.3%) male and 40 (23.7%) female patients, aged between 39 and 83, with the average of 62.53 ? 7.6. There was no statistically significant difference between the ages of different genders (p = 0.207). The most frequent diagnosis among cytological diagnoses was NSCLC in 99 (58.58%) patients. Concordance between cytological and histopathological diagnoses of surgical specimens was 61.48%. There was no statistically significant difference between cytological diagnoses and histopathological diagnoses of small biopsies specimens (p = 0.856). The sensitivity, specificity, positive and negative prognostic value, and accuracy of cytology as a diagnostic method of lung cancer were 94.98%, 98.60%, 95.72%, 98.35%, and 97.71%, respectively. Conclusion. Cytological diagnosis of NSCLC is accurate, with high sensitivity, specificity, and benefits for patients. Most patients are diagnosed with advanced cancer when there is no surgical therapy option, and the only available diagnostic material is a small biopsy sampled during bronchoscopy.

MYB RNA In Situ Hybridization Facilitates Sensitive and Specific Diagnosis of Adenoid Cystic Carcinoma Regardless of Translocation Status

Adenoid cystic carcinoma (AdCC) can demonstrate histologic and immunohistochemical (IHC) overlap with a wide range of salivary and nonsalivary tumors, especially in small biopsy specimens. While MYB fluorescence in situ hybridization (FISH) frequently is used to confirm the diagnosis of AdCC, the pathognomonic MYB-NFIB fusion is only present in 40% to 70% of cases. Likewise, although MYB RNA overexpression is seen in the vast majority of AdCC regardless of translocation status, MYB IHC has shown suboptimal specificity for this diagnosis. In this study, we sought to determine whether a novel chromogenic RNA in situ hybridization (ISH) platform could directly detect MYB RNA overexpression and offer a rapid diagnostic adjunct for AdCC. We performed MYB RNA ISH on 84 cases of AdCC as well as 128 other salivary tumors and 108 basaloid and sinonasal carcinomas that mimic AdCC. MYB RNA ISH was 92% sensitive for AdCC, including 97% of cases with MYB rearrangement and 83% without MYB rearrangement by FISH. It was also 89% specific for AdCC overall, with 95% specificity among other salivary tumors and 81% specificity in basaloid and sinonasal carcinomas. In contrast, MYB IHC was 94% sensitive but just 54% specific for AdCC. Overall, MYB RNA ISH provides superior sensitivity for the diagnosis of AdCC compared with MYB FISH and superior specificity compared with MYB IHC. This assay could provide a useful tool for rapidly confirming the diagnosis of AdCC in formalin-fixed, paraffin-embedded specimens.

Gut Mucosal Gene Expression and Metabolic Changes After Roux-en-Y Gastric Bypass Surgery.

Changes in the secretion of gut-derived peptide hormones have been associated with the metabolic benefits of Roux-en-Y gastric bypass (RYGB) surgery. In this study, the effects of RYGB on anthropometrics, postprandial plasma hormone responses, and mRNA expression in small intestinal mucosa biopsy specimens before and after RYGB were evaluated. In a cross-sectional study, 20 individuals with obesity undergoing RYGB underwent mixed meal tests and upper enteroscopy with retrieval of small intestinal mucosa biopsy specimens 3 months before and after surgery. Concentrations of circulating gut and pancreatic hormones during mixed meal tests as well as full mRNA sequencing of biopsy specimens were evaluated. RYGB-induced improvements of body weight and composition, insulin resistance, and circulating cholesterols were accompanied by significant changes in postprandial plasma responses of pancreatic and gut hormones. Global gene expression analysis of biopsy specimens identified 2,437 differentially expressed genes after RYGB, including changes in genes that encode prohormones and G protein-coupled receptors. RYGB affects the transcription of a wide range of genes, indicating that the observed beneficial metabolic effects of RYGB may rely on a changed expression of several genes in the gut. RYGB-induced changes in the expression of genes encoding signaling peptides and G protein-coupled receptors may disclose new gut-derived treatment targets against obesity and diabetes.

Isolated Hyponatremic Dehydration in the Setting of COVID-19–Associated Gastroenteritis in a Toddler

Isolated Hyponatremic Dehydration in the Setting of COVID-19–Associated Gastroenteritis in a Toddler

Gastric epithelioid gastrointestinal stromal tumor with signet ring-like cell features: A case report

A gastrointestinal stromal tumor (GIST) with signet ring cell features is a rare variant of epithelioid GIST. The current case demonstrates a 35-year-old woman with a 22.0 cm stomach mass. Tomography-guided core biopsy of the mass showed an undifferentiated tumor with abundant signet ring cells in a myxoid background. A preliminary diagnosis of adenocarcinoma was considered based on histomorphologic features; however, by immunohistochemistry studies the tumor cells were negative for cytokeratins and intensely positive for CD117/c-kit and CD34. Therefore a diagnosis of GIST with signet ring-like cells features was rendered. Making a diagnosis in a small biopsy specimen is always challenging, due to the variable histomorphological features of these tumors.

A RARE CASE OF DIAGNOSTICALLY CHALLENGING LUNG TUMOR

SESSION TITLE: Medical Student/Resident Lung Cancer Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: Inflammatory myofibroblastic tumor (IMT) and pulmonary sarcomatoid carcinoma (PSC) are rare tumors and account for less than 1% of primary lung malignancies [1]. We present a diagnostically challenging case of lung neoplasm that was initially diagnosed as IMT but was later found to be PSC. CASE PRESENTATION: A 56-year-old Hispanic male with diabetes mellitus type 2, hypertension, and smoking history was found to have a left lung mass while undergoing treatment for STEMI. He reported diminished appetite, 12 lbs. weight loss, and cough with pink sputum over the last 4-5 months. Lab results showed prominent leukocytosis and normocytic anemia. Treatment with wide spectrum antibiotics was stated for obstructive pneumonia. CT of the chest revealed a necrotic appearing 9x8 cm mass in the left upper lobe of the lung extending to the left hilum with invasion to the left superior pulmonary vein and extension into the left atrium (Pictures 1,2). CT guided lung and mediastinum biopsy initially favored bronchoalveolar carcinoma, but further analysis indicated IMT negative for ALK and ROS markers. Hence, patient was referred for tumor resection but another CT guided lung biopsy at the referred hospital was inconclusive for IMT. A surgical lung biopsy then revealed PSC positive for CD56 marker (Image 3). Neoadjuvant chemotherapy with cisplatin and etoposide, and radiation were started. Debulking surgery was planned later. Six months later patient experienced complex partial seizures, and a 1 cm lesion in the right anterolateral frontal lobe was discovered on MRI (Image 4). Mass resection confirmed it as metastatic PSC. Numerous bilateral cerebral hemispheric hemorrhagic metastases were diagnosed in the following three months. Patient expired 10 months from the date of PSC diagnosis. DISCUSSION: While IMT is a benign mesenchymal neoplasm mixed with inflammatory cells, PSC is carcinoma with at least 10% mesenchymal sarcoma-like elements. Treatment for both is surgical resection, but while recurrence after surgery is rare for IMT (2%), PSC has a poor prognosis with a 5-year survival rate of 20%-36%, compared to 91% for IMT [1,4]. It is very difficult to diagnose PSC and IMT on small biopsy specimens because it may not contain the mesenchymal/heterologous component, resulting in under-detection of PSC [2,4], which was also the reason for multiple biopsies in our patient. Also, spindle cell subtype of PSC may have prominent inflammatory stroma that could be mistaken for IMT [3,5]. CONCLUSIONS: An adequate specimen through surgical resection is critical for diagnosis IMT and PSC due to the heterogeneous composition of the tumors. Inadequate biopsy specimen may lead to misdiagnosis and treatment delay. Reference #1: Weissferdt A. Pulmonary Sarcomatoid Carcinomas: A Review. Adv Anat Pathol. 2018;25(5):304–313. Reference #2: Borczuk AC. Uncommon Types of Lung Carcinoma With Mixed Histology: Sarcomatoid Carcinoma, Adenosquamous Carcinoma, and Mucoepidermoid Carcinoma. Arch Pathol Lab Med. 2018;142(8):914-921. Reference #3: Travis WD. Sarcomatoid neoplasms of the lung and pleura. Arch Pathol Lab Med. 2010 Nov;134(11):1645-58. Sagar AES, Jimenez CA, Shannon VR. Clinical and Histopathologic Correlates and Management Strategies for Inflammatory Myofibroblastic tumor of the lung. A case series and review of the literature. Med Oncol. 2018;35(7):102. Surabhi VR, Chua S, Patel RP, Takahashi N, Lalwani N, Prasad SR. Inflammatory Myofibroblastic Tumors: Current Update. Radiol Clin North Am. 2016;54(3):553-63. DISCLOSURES: No relevant relationships by Olga Grigorieva Olson, source=Web Response No relevant relationships by Faizan Malik, source=Web Response No relevant relationships by dushyant pawar, source=Web Response

Current and future trends in non-small cell lung cancer biomarker testing: The American experience.

Biomarker testing in patients with advanced stage non-small cell lung cancer provides essential information that can be used to select the most appropriate therapy. The regular updates of guideline recommendations reflect the growing number of biomarkers that must be assessed, and as such signal the shift from single-gene assays to more comprehensive genomic profiling using next-generation sequencing modalities. Cytology and small biopsy specimens have proven to be more than adequate substrates for these types of ancillary molecular testing; however, other alternative testing substrates are beginning to emerge. These include so-called liquid biopsies as well the supernatant fluid from cytology specimens, both of which have demonstrated promise for use in the clinical realm. This review will briefly cover the current state of non-small cell lung cancer biomarker testing in the United States, with a focus on these novel nonconventional substrates that are increasingly being incorporated into testing paradigms.

ROLE OF VARIOUS IHC MARKERS IN CLASSIFICATION OF LUNG CARCINOMA ON ENDOBRONCHIAL BIOPSIES.

BACKGROUND: Lung cancer is the most frequently diagnosed cancer and leading cause among cancer mortality worldwide. An accurate classification is difficult in small biopsy specimens due to a variety of reasons. Therefore, there is an increasing need for additional diagnostic techniques such as immunohistochemistry. METHODS: This study was conducted on Endobronchial biopsies of One hundred and sixty patients were subjected to routine H & E and IHC staining. RESULTS: The patients were in age group of 25-75 years with a mean of 55.67 years with M: F ratio of 6.61:1. NSCLC constituted the major type, contributing to 83.1% of cases. Amongst, TTF-1 and napsin-A, the later had higher sensitivity (96.15%) as compared to TTF-1 (92.30%) for diagnosing adenocarcinoma. CONCLUSION: CK and p63 served as highly sensitive markers for diagnosis of squamous cell carcinoma and TTF-1 and napsin A for adenocarcinoma, forming an important diagnostic algorithm for subtyping of poorly differentiated NSCLC on small biopsies.

Extraskeletal myxoid chondrosarcoma: combining cytopathology with molecular testing to achieve diagnostic accuracy

Advances in the genetics of soft tissue neoplasia have allowed for the diagnostic recognition of specific tumor types from small biopsy specimens, including those procured using the fine needle aspiration (FNA) biopsy technique. Extraskeletal myxoid chondrosarcoma (EMC) is a malignant mesenchymal neoplasm characterized by NR4A3 and, less specifically, by EWSR1 gene rearrangements. A series of EMC cytologic specimens was examined to demonstrate the diagnostic value of incorporating fluorescence in situ hybridization (FISH) testing in cytologic cases of suspected EMC. A search was made of our cytopathology and surgical pathology databases for cases diagnosed as EMC. FNA biopsy cytology, exfoliative cytology, imprint cytology, and FISH analysis were performed and examined using standard techniques. A total of 16 cases of EMC were retrieved from 15 patients (male/female ratio, 2.8:1; mean age, 62 years). Of the 15 patients, 10 were new patients with primary tumors, 2 had locally recurrent tumors, and 4 had metastases. The sites included the extremities in 10 cases, the trunk in 4, serous effusion in 1, and a mediastinal lymph node in 1 case. The specific cytologic diagnoses were EMC (14 cases; 88%), suspicious for EMC (n = 1), and malignant cells (n = 1). All cases for which FISH testing was successfully used were specifically recognized as EMC. Aspirates and imprint smears consisted of uniformly rounded cells set in an opaque myxoid/chondromyxoid stroma (less abundant and more diaphanous in the effusion sample), sometimes arranged in short anastomosing cords. FNA of 1 case of an EMC cellular variant mimicked a malignant small rounded cell tumor. EMC can be added to the growing list of soft tissue neoplasms that are specifically recognizable using cytopathology, coupled with judicious application of ancillary molecular testing.

A new guideline from the College of American Pathologists to improve the adequacy of thoracic small specimens for ancillary studies.

With advancments in technology for minimally invasive sampling techniques, pathology laboratories are receiving increasing numbers of small biopsy and cytology specimens for multiple ancillary studies to help in the diagnosis and management of pulmonary diseases. A recently published evidence‐based guideline from the College of American Pathologists (CAP), in collaboration with 8 other professional medical societies, provides recommendations to clinicians for the collection of adequate material for diagnostic and ancillary testing as well as optimal handling in an attempt to prioritize ancillary testing. The primary goal of developing this CAP guideline is to assist pathologists and their clinical colleagues to better collect and handle small thoracic pathology specimens to help guide therapeutic decisions.

A review of mediastinal lesions encountered on fine needle aspiration and small biopsy specimens.

A review of mediastinal lesions encountered on fine needle aspiration and small biopsy specimens.

Evaluating triage protocols for endoscopic ultrasound-guided fine needle biopsies of the pancreas

Pancreatic endoscopic ultrasound-guided fine needle biopsy (EUS-FNB) acquires both direct smear and small core biopsy specimens. The triage protocols for pancreatic FNBs to cytopathology (CP) or gastrointestinal surgical pathology (GIP) are controversial and vary by institution. Pancreatic EUS-FNBs obtained with the SharkCore FNB were reviewed from January 2014 to June 2019. The specimen characteristics and pathology data, including tissue triage, were obtained from the electronic medical records. We assessed the diagnostic yield, defined as malignant, specific neoplastic, or benign, and the operating characteristics at the time of rapid on-site evaluation (ROSE) and final diagnosis. We reviewed 324 pancreatic FNBs from 313 patients. Of the 324 FNBs, 260 (80%) obtained concurrent direct smear and core biopsy specimens, 30 (12%) of which were divided between CP and GIP. Of the 51 core-only specimens, 47 (92%) were reviewed by CP and 4 (8%) by GIP. ROSE improved the overall diagnostic yield by 10% and accuracy by 9%. When core specimens were reviewed independently, the diagnostic accuracy was 93% for CP (n = 248) and 100% for GIP (n = 33). All false-negative results of the CP-reviewed cores were due to sampling error. Concurrent smear review improved EUS-FNB performance, increasing the negative predictive value by 10% and accuracy by 3% compared with core review alone. CP and GIP can accurately interpret pancreatic EUS-FNB specimens. However, triage of concurrent EUS-FNB-acquired smear and core specimens to CP may be most efficient as CPs are trained to assess adequacy at the time of ROSE, as well as interpretall parts of the biopsy, minimizing the risk of discordant pathology reports.

Bronchoscopic tissue yield for advanced molecular testing: are we getting enough?

The treatment of advanced lung cancer has become increasingly personalized over the past decade as a result of the improved understanding of tumor molecular biology and anti-tumor immunity. An adequate tumor sample is central to targetable mutation analysis, and immunologic profiling. The majority of lung cancer patients currently present at an advanced disease stage, so that diagnosis and staging are largely based on small biopsy and cytology specimens. Flexible bronchoscopy techniques play a prominent role in the acquisition of these diagnostic specimens. This narrative review summarizes the available evidence with regards to the role of various conventional and advanced flexible bronchoscopy techniques in acquiring sufficient tissue for mutation analysis and programmed death-ligand 1 (PD-L1) testing.

Promoted Viability and Differentiated Phenotype of Cultured Chondrocytes With Low Level Laser Irradiation Potentiate Efficacious Cells for Therapeutics.

Effective clinical treatments of cartilage lesions in affected joints require large numbers of viable chondrogenic cells generated through in vivo stimulation or ex vivo expansion of chondrocytes isolated from small biopsy specimens. Conventional passaging of chondrocytes in culture provides sufficient cells for treatments but these cells usually lose their differentiated phenotype. This leads to the formation of fibrocartilaginous tissue due to a malfunctioning repair process. Biostimulation of passaging chondrocytes with low level laser irradiation (LLLI) may theoretically produce more functional chondrocytes for cell-based repair of cartilage defects. Molecular and cellular analyses, cytochemistry, cell cultivation, and microscopy showed that LLLI treatments were found to (1) increase chondrocyte viability, (2) promote secretion of matrix proteins, (3) upregulate expression of chondrogenic genes, and (4) downregulate gene expression of cell destructive proteases and genes coding for mediators involved in the extrinsic apoptosis signaling pathway. Furthermore, LLLI attenuated induction of genes associated with cell death and matrix breakdown induced by IL-1β, some of which was seen at the protein level, with verification of effects on gene expression in the C28/I2 human chondrocyte line. LLLI treatments during culture generated larger numbers of viable chondrocytes compared to untreated cultures. Moreover, LLLI-treated chondrocytes in culture also rectified and simultaneously maintained their differentiated phenotype. Cultured chondrocytes treated with LLLI are a promising cell source for repairing cartilage lesions in vivo and restoration of articular function using tissue engineering strategies.

Collection and Handling of Thoracic Small Biopsy and Cytology Specimens for Ancillary Studies Guideline from the College of American Pathologists (CAP): implications for the cytology community

The methods of collecting and handling thoracic small biopsy and cytology specimens can greatly impact downstream ancillary testing success, especially for non-small cell lung cancer (NSCLC). The College of American Pathologists (CAP) in collaboration with multiple other professional societies has recently developed an evidence-based laboratory practice guideline to provide clarity on how to best optimize these pre-analytic variables for small thoracic specimens. A total of 16 guideline statements were developed based on systematic literature review and expert panel consensus, covering topics ranging from optimal materials and techniques for fine-needle aspiration and small biopsy sampling to acquire sufficient amounts of material, to the use of rapid on-site evaluation to help appropriately triage, handle, and process these specimens. These guideline statements hold many implications for the practicing cytologist, though perhaps none more important than the recognition that the variety of cytology specimens we work with on a daily basis (including smears, cell blocks, and liquid-based cytology) can certainly be used for ancillary studies if supported by adequate validation studies. This commentary provides a brief overview of the newly developed CAP thoracic small biopsy and cytology specimen collection and handling guideline, as well as a discussion of how it may specifically impact the cytology community.

Lymphomas of the Mediastinum and Their Differential Diagnosis.

Lymphoma is the most common malignancy involving the mediastinum but can be challenging to diagnose on small biopsy specimens. This review provides a pattern-based approach to help triage small tissue samples for the diagnosis of mediastinal lymphoid proliferations, with focus on the main primary mediastinal lymphomas. The use of ancillary studies is highlighted, along with considerations to avoid misdiagnosis and scenarios to request additional tissue.

Collection and Handling of Thoracic Small Biopsy and Cytology Specimens for Ancillary Studies: Guideline From the College of American Pathologists in Collaboration With the American College of Chest Physicians, Association for Molecular Pathology, American Society of Cytopathology, American Thoracic Society, Pulmonary Pathology Society, Papanicolaou Society of Cytopathology, Society of Interventional Radiology, and Society of Thoracic Radiology.

The need for appropriate specimen use for ancillary testing has become more commonplace in the practice of pathology. This, coupled with improvements in technology, often provides less invasive methods of testing, but presents new challenges to appropriate specimen collection and handling of these small specimens, including thoracic small biopsy and cytology samples. To develop a clinical practice guideline including recommendations on how to obtain, handle, and process thoracic small biopsy and cytology tissue specimens for diagnostic testing and ancillary studies. The College of American Pathologists convened an expert panel to perform a systematic review of the literature and develop recommendations. Core needle biopsy, touch preparation, fine-needle aspiration, and effusion specimens with thoracic diseases including malignancy, granulomatous process/sarcoidosis, and infection (eg, tuberculosis) were deemed within scope. Ancillary studies included immunohistochemistry and immunocytochemistry, fluorescence in situ hybridization, mutational analysis, flow cytometry, cytogenetics, and microbiologic studies routinely performed in the clinical pathology laboratory. The use of rapid on-site evaluation was also covered. Sixteen guideline statements were developed to assist clinicians and pathologists in collecting and processing thoracic small biopsy and cytology tissue samples. Based on the systematic review and expert panel consensus, thoracic small specimens can be handled and processed to perform downstream testing (eg, molecular markers, immunohistochemical biomarkers), core needle and fine-needle techniques can provide appropriate cytologic and histologic specimens for ancillary studies, and rapid on-site cytologic evaluation remains helpful in appropriate triage, handling, and processing of specimens.

Benign lesions of the mediastinum: A review with emphasis on cytology and small biopsy specimens.

This review focuses on the diagnosis of select benign processes, ranging from reactive entities to heterotopic tissues to neoplasms, which may occur in the mediastinum. Currently, the mediastinum can be evaluated and biopsied with endoscopic procedures. Therefore, cytopathology specimens, fine needle aspirations, and small biopsies play an important role in the diagnosis of these lesions. In this review, an emphasis is given to relevant clinical presentations, histologic and cytologic findings, differential diagnoses, ancillary testing, and interpretation. Pitfalls are reviewed and discussed in each section. It is important for both surgical pathologists and cytopathologists to be familiar with these entities and their cytologic and histologic features that may be helpful in reaching a diagnosis.

Is tissue still the issue in detecting molecular alterations in lung cancer?

Molecular biomarker testing of advanced-stage NSCLC is now considered standard of care and part of the diagnostic algorithm to identify subsets of patients for molecular-targeted treatment. Tumour tissue biopsy is essential for an accurate initial diagnosis, determination of the histological subtype and for molecular testing. With the increasing use of small biopsies and cytological specimens for diagnosis and the need to identify an increasing number of predictive biomarkers, proper management of the limited amount of sampling materials available is important. Many patients with advanced NSCLC do not have enough tissue for molecular testing and/or do not have a biopsy-amenable lesion and/or do not want to go through a repeat biopsy given the potential risks. Molecular testing can be difficult or impossible if the sparse material from very small biopsy specimens has already been exhausted for routine diagnostic purposes. A limited diagnostic workup is recommended to preserve sufficient tissue for biomarker testing. In addition, tumour biopsies are limited by tumour heterogeneity, particularly in the setting of disease resistance, and thus may yield false-negative results. Hence, there have been considerable efforts to determine if liquid biopsy in which molecular alterations can be non-invasively identified in plasma cell-free ctDNA, a potential surrogate for the entire tumour genome, can overcome the issues with tissue biopsies and replace the need for the latter.