The current state of digital cytology and artificial intelligence (AI): global survey results from the American Society of Cytopathology Digital Cytology Task Force.

INTRODUCTION: The integration of whole slide imaging (WSI) and artificial intelligence (AI) with digital cytology has been growing gradually. Therefore, there is a need to evaluate the current state of digital cytology. This study aimed to determine the current landscape of digital cytology via a survey conducted as part of the American Society of Cytopathology (ASC) Digital Cytology White Paper Task Force. MATERIALS AND METHODS: A survey with 43 questions pertaining to the current practices and experiences of WSI and AI in both surgical pathology and cytology was created. The survey was sent to members of the ASC, the International Academy of Cytology (IAC), and the Papanicolaou Society of Cytopathology (PSC). Responses were recorded and analyzed. RESULTS: In total, 327 individuals participated in the survey, spanning a diverse array of practice settings, roles, and experiences around the globe. The majority of responses indicated there was routine scanning of surgical pathology slides (n = 134; 61%) with fewer respondents scanning cytology slides (n = 150; 46%). The primary challenge for surgical WSI is the need for faster scanning and cost minimization, whereas image quality is the top issue for cytology WSI. AI tools are not widely utilized, with only 16% of participants using AI for surgical pathology samples and 13% for cytology practice. CONCLUSIONS: Utilization of digital pathology is limited in cytology laboratories as compared to surgical pathology. However, as more laboratories are willing to implement digital cytology in the near future, the establishment of practical clinical guidelines is needed.

Digital cytology part 1: digital cytology implementation for practice: a concept paper with review and recommendations from the American Society of Cytopathology Digital Cytology Task Force.

Digital cytology and artificial intelligence (AI) are gaining greater adoption in the cytopathology laboratory. However, peer-reviewed real-world data and literature are lacking regarding the current clinical landscape. The American Society of Cytopathology in conjunction with the International Academy of Cytology and the Digital Pathology Association established a special task force comprising 20 members with expertise and/or interest in digital cytology. The aim of the group was to investigate the feasibility of incorporating digital cytology, specifically cytology whole slide scanning and AI applications, into the workflow of the laboratory. In turn, the impact on cytopathologists, cytologists (cytotechnologists), and cytology departments were also assessed. The task force reviewed existing literature on digital cytology, conducted a worldwide survey, and held a virtual roundtable discussion on digital cytology and AI with multiple industry corporate representatives. This white paper, presented in 2 parts, summarizes the current state of digital cytology and AI practice in global cytology practice. Part 1 of the white paper presented herein is a review and offers best practice recommendations for incorporating digital cytology into practice. Part 2 of the white paper provides a comprehensive review of AI in cytology practice along with best practice recommendations and legal considerations. Additionally, the results of a global survey regarding digital cytology are highlighted.

Digital cytology part 2: artificial intelligence in cytology: a concept paper with review and recommendations from the American Society of Cytopathology Digital Cytology Task Force.

Digital cytology and artificial intelligence (AI) are gaining greater adoption in the cytology laboratory. However, peer-reviewed real-world data and literature are lacking in regard to the current clinical landscape. The American Society of Cytopathology in conjunction with the International Academy of Cytology and the Digital Pathology Association established a special task force comprising 20 members with expertise and/or interest in digital cytology. The aim of the group was to investigate the feasibility of incorporating digital cytology, specifically cytology whole slide scanning and AI applications, into the workflow of the laboratory. In turn, the impact on cytopathologists, cytologists (cytotechnologists), and cytology departments were also assessed. The task force reviewed existing literature on digital cytology, conducted a worldwide survey, and held a virtual roundtable discussion on digital cytology and AI with multiple industry corporate representatives. This white paper, presented in 2 parts, summarizes the current state of digital cytology and AI practice in global cytology practice. Part 1 of the white paper is presented as a separate paper which details a review and best practice recommendations for incorporating digital cytology into practice. Part 2 of the white paper presented here provides a comprehensive review of AI in cytology practice along with best practice recommendations and legal considerations. Additionally, the cytology global survey results highlighting current AI practices by various laboratories, as well as current attitudes, are reported.

A brief review of the WHO reporting system for lung cytopathology.

The International Academy of Cytology has joined with the International Agency for Research on Cancer to bring together a group of experts in lung cytopathology to develop a WHO Reporting System for Lung Cytopathology (WHO System). This System aims to improve and standardize the reporting of cytopathology, facilitate communication between cytopathologists and clinicians, and improve patient care. The WHO System describes 5 categories for reporting lung cytopathology: 'Insufficient/Inadequate/Nondiagnostic', 'Benign', 'Atypical', 'Suspicious for malignancy', and 'Malignant', each one with a clear descriptive term, a definition, a risk of malignancy, and a suggested management algorithm. The key diagnostic cytopathologic features of each of the lesions within each category have been established by consensus through an Expert Editorial Board, who are also the authors of this review and selected for each reporting system and chosen based on their expertise in the field and/or diversity of geographical representation. Many other co-authors from around the world also contributed. The assignment of writing and editing responsibilities used the same model as that used for the WHO Classification of Tumours (https://whobluebooks.iarc.fr/about/faq/). The WHO System provides the best practice application of ancillary testing, including immunocytochemistry and molecular pathology, and guides in sampling and processing techniques to optimize the handling and preparation of specimens. The WHO System was created by the authors to be applicable globally and is based on cytomorphology with possibilities for additional diagnostic management of the patient. The authors are aware that local medical and pathology resources would differ, especially in low- and middle-income countries. The WHO Tumour Classification for Thoracic Tumors, Fifth Edition, is directly accessible through the online WHO System.

The World Health Organization Reporting System for Lung Cytopathology.

The International Academy of Cytology has joined with the International Agency for Research on Cancer (IARC) to bring together a group of experts in lung cytopathology to develop a WHO Reporting System for Lung Cytopathology (WHO System). This WHO System defines five categories for reporting lung cytopathology, that is, "Insufficient"/"Inadequate"/"Non-diagnostic," "Benign," "Atypical," "Suspicious for malignancy," and "Malignant," each with a clear descriptive term for the category, a definition, a risk of malignancy and a suggested management algorithm. The key diagnostic cytopathology features of each of the lesions within each category have been established by consensus and will be presented more fully in a subsequent IARC e-book and published hard cover book.The WHO System provides the best practice application of ancillary testing, including immunocytochemistry and molecular pathology, and provides a review to guide sampling and processing techniques to optimize the handling and preparation of the cytopathology sample emphasizing the cytomorphological differential diagnosis to aid low-resourced settings. The authors recognize that local medical and pathology resources will vary, particularly in low- and middle-income countries, and have developed the WHO System to make it applicable worldwide based on cytomorphology with options for further diagnostic management of the patient.The online WHO System provides a direct link to the WHO Tumour Classification for Thoracic Tumours 5th Edition. It will raise the profile and use of cytopathology by increasing awareness of its current role and its potential role in the era of personalized medicine based on molecular pathology utilizing "small biopsies." Ultimately, the System will improve patient care and outcomes.This System aims to improve and standardize the reporting of cytopathology, facilitate communication between cytopathologists and clinicians and improve patient care. The System is based on the current role of lung cytopathology and synthesizes the existing evidence while highlighting areas requiring further research and the future potential role of lung cytopathology.

Melanotic medullary thyroid carcinoma: A case report with review of the literature.

Melanotic medullary thyroid carcinoma is morphologically defined by the presence of melanin deposits in the cytoplasm of tumor cells. It is an extremely rare variant with only 15 cases described in the literature to date and only one report of diagnosis by fine needle aspiration (FNA) biopsy. A 51-year-old woman presented with neck swelling. An ultrasound examination revealed a single solid nodule in the right thyroid lobe that measured 5.4 × 4.7 × 4.3 cm. Laboratory examination revealed elevated levels of serum calcitonin (8643.0 pg/ml), carcinoembryonic antigen (CEA) (86.2 ng/ml), and chromogranin A (123.2 ng/ml). An FNA biopsy of the thyroid nodule revealed predominantly single plasmacytoid cells with round to oval eccentric nuclei and dark brown intracytoplasmic granules. Immunohistochemical studies with Melan-A performed on a cell block slide confirmed that the granules contained melanin. The tumor cells were also positive for calcitonin, CEA, synaptophysin, AE1/AE3, CAM5.2, and HMB-45(focal); the tumor cells were negative for chromogranin, thyroglobulin, PAX8 and TTF-1. The diagnosis was reported as melanotic variant of medullary thyroid carcinoma. The patient underwent a total thyroidectomy which revealed tumor cell expression of insulinoma-associated protein 1 and confirmed neuroendocrine differentiation. Shortly after she presented with tumor recurrence in the thyroidectomy bed. The tumor cells were positive for only S100, SOX10, and Melan-A. Molecular analysis with the SEMA4 Solid Tumor Panel revealed mutations in the HRAS, PIK3CA, PIK3R1, MYC, and CCND3 genes. The final diagnosis was reported as melanocytic medullary thyroid carcinoma with high grade transformation and loss of epithelial and neuroendocrine expression.

A comparative study of the genotype profiles of high-risk human papillomavirus infection in male and female HIV-positive patients and their correlation with anal cytology and biopsy.

INTRODUCTION: Although anal cancer is more common in women, most of the studies on the role of high-risk human papillomavirus (hrHPV) infection in anal squamous lesions have focused on high-risk male patients. Therefore, we compared the genotype profile and clinicopathologic correlation of hrHPV infection in human immunodeficiency virus-positive (HIV+) men and women. MATERIALS AND METHODS: We retrospectively analyzed 2254 HIV+ patients (1931 men and 323 women) who had undergone anal Papanicolaou tests at our institution; 1189 of them also had follow-up biopsy data available. HPV genotyping was performed using the Roche Cobas system and correlated with the cytologic and histologic diagnosis. RESULTS: Compared with the HIV+ men, the HIV+ women had a significantly lower rate of hrHPV infection (67.5% versus 78.5%; P < 0.0001) but a significantly higher rate of high-grade squamous intraepithelial lesions (HSILs) on anal Papanicolaou tests (4.6% versus 2.5%; P < 0.05). Other high-risk HPV (ohrHPV), as a group, is much more common than HPV16 or HPV18 in both genders. HIV+ women had significantly lower HPV16 and ohrHPV infection rates than did HIV+ men. However, the HPV18 infection rates were similar between HIV+ women and HIV+ men. For both genders, the rates of HSILs or high-grade anal intraepithelial neoplasia (AIN2-3) were significantly increased when coinfection of ohrHPV with either HPV16 or HPV18 was present. CONCLUSIONS: Although both HIV+ men and HIV+ women have an increased risk of hrHPV infection, HIV+ women have different hrHPV genotype profiles and higher rates of high-grade lesions. Coinfection with different genotypes of hrHPV can significantly increase the risk of HSILs or AIN2-3 in both genders and could requires vigilant clinical and laboratory follow-up.

Building a smart FNA cart: When Google meets cytology.

BACKGROUND: The appropriate management of a fine needle aspiration (FNA) supply cart and equipment set up is essential to ensure the smooth and optimal operation of a busy FNA clinic. We applied Lean strategies such as value stream mapping (VSM), the 5S method (Sort, Set in order, Shine, Standardize, Sustain), and Kanban to remove waste and improve patient flow in an FNA clinic. METHODS: The workflow analysis suggested that existent problems such as suboptimal inventory management and unavailability of standard operating procedures (SOPs) caused a 10% to 85% increase in total procedure time. To improve inventory management, we created a 2-bin Kanban system. We used the "Scan to Web" app and a Google Drive form to create a cost-effective electronic inventory management system. We distributed the essential SOPs in the format of video clips using our YouTube channel and leveraged barcode technology to access the links. RESULTS: Upon completion of our process improvement project, we succeeded to eliminate the stock-out events and maintain a process cycle efficiency of 87%. The 5S audit checklist result increased from 6% to 100% implementation, which is consistent with focused improvement. The developed inventory system enabled us to track the supply usage, forecast demands, and improve the accuracy of orders. CONCLUSIONS: Lean methods such as VSM, 5S, and Kanban combined with open source technologies can be implemented to ensure material availability, track inventory, and provide immediate access to SOPs on demand. The developed system also led to increased efficiency and improved flow, as well as responsiveness to changes in demand.

Cytological features of noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP).

INTRODUCTION: The noninvasive encapsulated follicular variant of papillary carcinoma (EFVPC) was recently renamed a noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) because of its unique genetic alterations and biological behavior. The objective of this report is to help cytopathologists and cytotechnologists improve diagnostic accuracy and determine the need for cytogenetic studies during adequacy evaluation of thyroid fine-needle aspirations. MATERIALS AND METHODS: Fifty-five cases of surgery-proven noninvasive EFVPC with corresponding cytology material were reviewed. These cases were collected over 17 years, from 1999 to 2016. RESULTS: Thirty-four of 55 (61.8%) cases were diagnosed as follicular neoplasm or suspicious for follicular neoplasm on cytology. Eighty to ninety percent of cases showed scant colloid, cellular smears with small clusters of follicular cells with nuclear atypia including enlarged nuclei, oval-shaped nuclei, nuclear grooves, mild chromatin powdering, and rare nuclear pseudo-inclusions. CONCLUSIONS: NIFTP has unique features: cytologically similar to follicular neoplasms, and nuclear atypia falling between atypia of undetermined significance (category III) and suspicious for/and papillary thyroid carcinoma (category V/VI) (The Bethesda System for Reporting Thyroid Cytopathology).

Analytic inquiry: Molecular testing in lung cancer.

Non-small cell lung cancer is a different disease from what it was a decade ago. The last 10 years were based on remarkable advances in the understanding of key genetic alterations that function as oncogenic drivers and serve as therapeutic targets, thereby defining new molecular subsets. These changes have had an impact on clinical care, patient outcomes, and pathologic diagnosis and present new challenges in the approach of the cytopathologist to this still deadly disease. To meet these new challenges and appropriately train the next generation of cytopathologists, the complex molecular background underlying this disease and the implications that cytologic and histologic diagnoses have on treatment must be understood. Herein, the author reviews the background leading to this new approach and explains how, why, and what cytologists need to know to successfully contribute to the care of the patient with lung cancer. Cancer Cytopathol 2017;125(6 suppl):470-6. © 2017 American Cancer Society.

Morphologic Accuracy in Differentiating Primary Lung Adenocarcinoma From Squamous Cell Carcinoma in Cytology Specimens.

CONTEXT: -The National Cancer Care Network and the combined College of American Pathologists/International Association for the Study of Lung Cancer/Association for Molecular Pathology guidelines indicate that all lung adenocarcinomas (ADCs) should be tested for epidermal growth factor receptor (EGFR) mutations and anaplastic lymphoma kinase (ALK) rearrangements. As the majority of patients present at a later stage, the subclassification and molecular analysis must be done on cytologic material. OBJECTIVE: -To evaluate the accuracy and interobserver variability among cytopathologists in subtyping non-small cell lung carcinoma using cytologic preparations. DESIGN: -Nine cytopathologists from different institutions submitted cases of non-small cell lung carcinoma with surgical follow-up. Cases were independently, blindly reviewed by each cytopathologist. A diagnosis of ADC or squamous cell carcinoma was rendered based on the Diff-Quik, Papanicolaou, and hematoxylin-eosin stains. The specimen types included fine-needle aspiration from lung, lymph node, and bone; touch preparations from lung core biopsies; bronchial washings; and bronchial brushes. A major disagreement was defined as a case being misclassified 3 or more times. RESULTS: -Ninety-three cases (69 ADC, 24 squamous cell carcinoma) were examined. Of 818 chances (93 cases × 9 cytopathologists) to correctly identify all the cases, 753 correct diagnoses were made (92% overall accuracy). Twenty-five of 69 cases of ADC (36%) and 7 of 24 cases of squamous cell carcinoma (29%) had disagreement (P = .16). Touch preparations were more frequently misdiagnosed compared with other specimens. Diagnostic accuracy of each cytopathologist varied from 78.4% to 98.7% (mean, 91.7%). CONCLUSION: -Lung ADC can accurately be distinguished from squamous cell carcinoma by morphology in cytologic specimens with excellent interobserver concordance across multiple institutions and levels of cytology experience.

Comprehensive Genomic Profiling Identifies a Subset of Crizotinib-Responsive ALK-Rearranged Non-Small Cell Lung Cancer Not Detected by Fluorescence In Situ Hybridization.

INTRODUCTION: For patients with non-small cell lung cancer (NSCLC) to benefit from ALK inhibitors, sensitive and specific detection of ALK genomic rearrangements is needed. ALK break-apart fluorescence in situ hybridization (FISH) is the U.S. Food and Drug Administration approved and standard-of-care diagnostic assay, but identification of ALK rearrangements by other methods reported in NSCLC cases that tested negative for ALK rearrangements by FISH suggests a significant false-negative rate. We report here a large series of NSCLC cases assayed by hybrid-capture-based comprehensive genomic profiling (CGP) in the course of clinical care. MATERIALS AND METHODS: Hybrid-capture-based CGP using next-generation sequencing was performed in the course of clinical care of 1,070 patients with advanced lung cancer. Each tumor sample was evaluated for all classes of genomic alterations, including base-pair substitutions, insertions/deletions, copy number alterations and rearrangements, as well as fusions/rearrangements. RESULTS: A total of 47 patients (4.4%) were found to harbor ALK rearrangements, of whom 41 had an EML4-ALK fusion, and 6 had other fusion partners, including 3 previously unreported rearrangement events: EIF2AK-ALK, PPM1B-ALK, and PRKAR1A-ALK. Of 41 patients harboring ALK rearrangements, 31 had prior FISH testing results available. Of these, 20 were ALK FISH positive, and 11 (35%) were ALK FISH negative. Of the latter 11 patients, 9 received crizotinib based on the CGP results, and 7 achieved a response with median duration of 17 months. CONCLUSION: Comprehensive genomic profiling detected canonical ALK rearrangements and ALK rearrangements with noncanonical fusion partners in a subset of patients with NSCLC with previously negative ALK FISH results. In this series, such patients had durable responses to ALK inhibitors, comparable to historical response rates for ALK FISH-positive cases. IMPLICATIONS FOR PRACTICE: Comprehensive genomic profiling (CGP) that includes hybrid capture and specific baiting of intron 19 of ALK is a highly sensitive, alternative method for identification of drug-sensitive ALK fusions in patients with non-small cell lung cancer (NSCLC) who had previously tested negative using standard ALK fluorescence in situ hybridization (FISH) diagnostic assays. Given the proven benefit of treatment with crizotinib and second-generation ALK inhibitors in patients with ALK fusions, CGP should be considered in patients with NSCLC, including those who have tested negative for other alterations, including negative results using ALK FISH testing.

Standardized terminology and nomenclature for respiratory cytology: The Papanicolaou Society of Cytopathology guidelines.

BACKGROUND: The Papanicolaou Society of Cytopathology has developed a set of guidelines for respiratory cytology including indications for cytologic testing, techniques for cytologic sampling, terminology and nomenclature for respiratory diseases, ancillary testing, and recommendations for postcytologic diagnosis follow-up and management. METHODS: All documents are based on the expertise of the authors, an extensive literature review and discussions of the draft documents at national and international meetings over a 12-month period. This document selectively presents the results of these discussions and reports a proposed standardized terminology scheme for respiratory cytology that correlates cytologic diagnosis with biologic behavior and patient management. RESULTS: The classification and terminology scheme recommends a six-tiered system composed of: nondiagnostic, negative, atypical, neoplastic (benign and neoplasms of low malignant potential), suspicious, and positive for malignancy. CONCLUSION: The scheme recommends statements on specimen adequacy followed by the major classification category and then a subclassification and/or comments section. Each of the six main diagnostic categories is associated with an estimated risk of malignancy. Subsequent documents will propose ancillary testing recommendations, techniques for cytologic sampling, indications for cytologic study and postcytologic diagnosis management and follow-up recommendations.

Imaging appearances of diffuse idiopathic pulmonary neuroendocrine cell hyperplasia.

OBJECTIVE: The objective of the study was to describe the imaging appearances of diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) on computed tomography (CT). MATERIALS AND METHODS: Electronic medical records were searched for patients with pathology-proven DIPNECH who had a CT available for review. Eleven patients were included. RESULTS: The most common finding on CT was small pulmonary nodules which were present in all patients and were multiple (≥5) in 7/11 patients. Other CT findings included mosaic pattern attenuation and bronchial wall thickening/bronchiectasis. CONCLUSION: DIPNECH should be considered as a diagnostic possibility when multiple small pulmonary nodules are identified on CT, particularly if there is an associated carcinoid tumor.

Low interobserver agreement in cytology grading of mucinous pancreatic neoplasms.

BACKGROUND: Identifying high-grade features in patients with pancreatic mucinous neoplasms (MNs) is important for patient management. The reproducibility of MN cytology grading has been evaluated to a limited extent. In the current study, the authors evaluated interobserver variability in grading MNs and the identification of neoplastic mucin in endoscopic ultrasound-guided fine-needle aspiration specimens. METHODS: A 54-case grading set was created from histologically confirmed MNs (44 MNs) and nonmucinous lesions with abundant gastrointestinal contamination (10 nonmucinous lesions). Six observers received a tutorial, reviewed prescreened slides, and recorded: 1) a diagnosis according to a 6-tiered system (TS) (nondiagnostic, atypical [ATP], mucinous cyst low grade [MCLG], mucinous cyst high grade, suspicious for adenocarcinoma, and positive for adenocarcinoma); 2) the cyst fluid carcinoembryonic antigen diagnosis (CEADX); and 3) the presence of neoplastic musin. Interobserver agreement (IOA) was evaluated by calculation of kappa coefficients (Kappa). Diagnostic accuracy was not evaluated. RESULTS: The IOA was lowest for the 6-TS (Kappa, 0.13; P<.001). The CEADX was available for 18 cases (33%), including 6 of 24 MCLG cases (25%). CEADX modestly improved IOA for combined tiers of the 6-TS with ATP and MCLG as separate categories. The highest IOA was noted with a 3-TS (nondiagnostic, ATP/MCLG, and mucinous cyst high grade/suspicious for adenocarcinoma/positive for adenocarcinoma [Kappa, 0.28; P<.001]) and various 4-TS (Kappa, 0.22-0.23). IOA was found to be low for neoplastic mucin (Kappa = 0.15; P<.001). CONCLUSIONS: In a study using simulated cytology practice, observers demonstrated fair IOA for grading MNs and low IOA for identifying neoplastic mucin. Knowledge of the cyst fluid CEA level was found to modestly improve the IOA for low-grade lesions.

Small-cell lung cancers in patients who never smoked cigarettes.

INTRODUCTION: We describe clinical, pathologic, and molecular characteristics of never-smoker patients with small-cell lung cancers (SCLCs). METHODS: We identified cases of SCLCs evaluated at our institution from 2005 to 2012. We collected smoking history, demographic, treatment, and survival data. EGFR, KRAS, PIK3CA, ALK testing, RB protein expression, and next generation sequencing were performed on available samples. RESULTS: Two percent (23 of 1040) of patients with SCLCs were never-smokers. Eighty-three percent (19 of 23) had de novo SCLCs, whereas 17% had SCLC transformation as acquired resistance to erlotinib after treatment for EGFR-mutant lung carcinomas. Median survival from SCLC diagnosis was 23 months. Of de novo SCLCs, ALK rearrangement, KRAS mutations, EGFR mutations, and RB loss were identified in zero of five, zero of eight, two of eight, and six of seven, respectively. Two de novo samples underwent next generation sequencing. One had mutations in p53 and RB1 with amplification in TERT, and a second had mutations in CBL and GNAS with amplification in MYCL1. CONCLUSIONS: Two percent of patients with SCLCs are never-smokers. Although transformation to SCLC can rarely occur in acquired resistance to erlotinib, 83% of never-smokers with SCLCs had de novo SCLC. RB loss was noted in 86% of cases. Multiplexed genotyping can be performed on tissues to identify potentially actionable oncogenic drivers.

Metastatic Medullary Thyroid Carcinoma and Cabozantinib: Case Series and Review of Literature.

Cabozantinib, a tyrosine kinase inhibitor, was approved by the US Food and Drug Administration in November 2012, for the treatment of metastatic medullary thyroid carcinoma. Although side effects typically include stomatitis, palmar-plantar erythrodysesthesia syndrome, hypertension and diarrhea, most patients are able to tolerate the recommended dose of 140 mg daily. Surgical resection is the primary treatment for medullary thyroid carcinoma. Patients with metastatic disease, who are not candidates for surgery, are considered candidates for systemic therapy. However, systemic chemotherapy has a limited role in metastatic disease. Our paper highlights not only the malignant potential of a medullary thyroid carcinoma, but also the role of cabozantinib in patients with progressive metastatic disease. We report two cases of patients with progressive metastatic medullary thyroid carcinoma (involving lung, lymph nodes, liver, pancreas, brain and spine) who responded well to therapy with cabozantinib.