Algorithmic Approach to the Splenic Lesion Based on Radiologic-Pathologic Correlation.

Splenic lesions are commonly discovered incidentally at imaging, without clinical signs or symptoms that may aid in diagnosis. As such, the differential diagnosis and subsequent management are based primarily on imaging characteristics. Much has been written about the myriad pathologic conditions that can occur in the spleen; however, there is little guidance on the approach to an incidental splenic mass. Applying an approach frequently used in imaging to the splenic mass-based on the number and consistency of lesions and refined by supplementary imaging features-allows formulation of a useful differential diagnosis. Solitary cystic masses include true cysts, pseudocysts, and parasitic cysts. When multiple cystic lesions are present, the differential diagnosis expands to include infectious lesions (abscess or microabscesses) and lymphangioma (a benign cystic neoplasm). Hemangioma is the most common solitary solid mass, although other vascular lesions (hamartoma, sclerosing angiomatoid nodular transformation) and nonvascular lesions (inflammatory pseudotumor, lymphoma) manifest as solitary and solid. When multiple solid masses are present, diffuse inflammatory disease (sarcoidosis), littoral cell angioma, and lymphoma should be considered. Malignancies, such as angiosarcoma or metastasis, can manifest as solitary or multiple and solid or cystic masses but are typically associated with symptoms or widespread primary malignancy. Careful assessment of the multimodality imaging characteristics of splenic lesions based on this approach aids the radiologist faced with the incidental splenic lesion. Online supplemental material is available for this article. Work of the U.S. Government published under an exclusive license with the RSNA.

Approach to Cystic Lesions in the Abdomen and Pelvis, with Radiologic-Pathologic Correlation.

Cystic lesions found in and around the peritoneal cavity can often be challenging to diagnose owing to significant overlap in imaging appearance between the different entities. When the cystic lesion can be recognized to arise from one of the solid abdominal organs, the differential considerations can be more straightforward; however, many cystic lesions, particularly when large, cannot be clearly associated with one of the solid organs. Cystic lesions arising from the mesentery and peritoneum are less commonly encountered and can be caused by relatively rare entities or by a variant appearance of less-rare entities. The authors provide an overview of the classification of cystic and cystic-appearing lesions and the basic imaging principles in evaluating them, followed by a summary of the clinical, radiologic, and pathologic features of various cystic and cystic-appearing lesions found in and around the peritoneal cavity, organized by site of origin. Emphasis is given to lesions arising from the mesentery, peritoneum, or gastrointestinal tract. Cystic lesions arising from the liver, spleen, gallbladder, pancreas, urachus, adnexa, or soft tissue are briefly discussed and illustrated with cases to demonstrate the overlap in imaging appearance with mesenteric and peritoneal cystic lesions. When approaching a cystic lesion, the key imaging features to assess include cyst content, locularity, wall thickness, and presence of internal septa, solid components, calcifications, or any associated enhancement. While definitive diagnosis is not always possible with imaging, careful assessment of the imaging appearance, location, and relationship to adjacent structures can help narrow the differential diagnosis. Online supplemental material is available for this article. ©RSNA, 2021.

Esophageal Neoplasms: Radiologic-Pathologic Correlation.

The epidemiology and clinical management of esophageal carcinomas are changing, and clinical imagers are required to understand both the imaging appearances of common cancers and the pathologic diagnoses that drive management. Rare esophageal malignancies and benign esophageal neoplasms have distinct imaging features that may suggest a diagnosis and guide the next steps clinically. Furthermore, these imaging features have a basis in pathology, and this article focuses on the relationship between pathologic features and imaging manifestations that will help an informed imager maintain clinical relevance.

Use of ring-enhancement and focal necrosis to differentiate pancreatic adenosquamous carcinoma from pancreatic ductal adenocarcinoma on CT and MRI.

PURPOSE: To assess the ability of the ring-enhancing sign and focal necrosis to diagnose adenosquamous carcinoma (ASqC), a variant of pancreatic ductal adenocarcinoma (PDAC), on MRI and CT. METHODS: The following features of ASqC and conventional PDAC were evaluated on CT and MRI: tumor size, location, margins, borders (non-exophytic, exophytic), and T1 signal intensity. Two readers, blinded to histopathology results, rated their confidence in detecting ring-enhancement and focal necrosis (FN) on a 5-point Likert scale on both MRI and CT. Inter-reader agreement was assessed with Cohen's kappa (k). RESULTS: A total of 24 patients were included: eight patients with treatment naïve and histologically proven ASqC (six women, mean age: 63, range: 40-75) and 16 patients with PDAC (eight women, mean age: 67, range: 47-83). Statistically significant differences between ASqC and PDAC were seen in tumor size, location, presence of FN, and ring enhancement (p = 0.01-0.037). The readers were more confident in depicting the key differentiating feature ring-enhancement in ASqC on MRI compared to CT (confidence 1.71 ± 0.49 vs. 0.88 ± 0.35, p = 0.017) with moderate inter-reader agreement (k = 0.46 and 0.5, respectively). FN showed substantial inter-reader agreement on MR and moderate agreement on CT (k = 0.67 and 0.5, respectively). CONCLUSIONS: Compared to CT, MRI depicts ring-enhancement in ASqC with greater reader confidence and FN in ASqC with higher inter-reader agreement. The concurrent presence of these two imaging features should raise high suspicion for ASqC.

Pancreatic Ductal Adenocarcinoma and Its Variants: Pearls and Perils.

Pancreatic ductal adenocarcinoma (PDAC), an epithelial neoplasm derived from the pancreatic ductal tree, is the most common histologic type of pancreatic cancer and accounts for 85%-95% of all solid pancreatic tumors. As a highly lethal malignancy, it is the seventh leading cause of cancer death worldwide and is responsible for more than 300 000 deaths per year. PDAC is highly resistant to current therapies, affording patients a 5-year overall survival rate of only 7.2%. It is characterized histologically by its highly desmoplastic stroma embedding tubular and ductlike structures. On images, it typically manifests as a poorly defined hypoenhancing mass, causing ductal obstruction and vascular involvement. Little is known about the other histologic subtypes of PDAC, mainly because of their rarity and lack of specific patterns of disease manifestation. According to the World Health Organization, these variants include adenosquamous carcinoma, colloid carcinoma, hepatoid carcinoma, medullary carcinoma, signet ring cell carcinoma, undifferentiated carcinoma with osteoclast-like giant cells, and undifferentiated carcinoma. Depending on the subtype, they can confer a better or even worse prognosis than that of conventional PDAC. Thus, awareness of the existence and differentiation of these variants on the basis of imaging and histopathologic characteristics is crucial to guide clinical decision making for optimal treatment and patient management.

Role of Multimodality Imaging in Gastroesophageal Reflux Disease and Its Complications, with Clinical and Pathologic Correlation.

Gastroesophageal reflux disease (GERD) is a common condition and impairs the quality of life for millions of patients, accounts for considerable health care spending, and is a primary risk factor for esophageal adenocarcinoma. There have been substantial advances in understanding the pathogenesis of GERD and its complications and much progress in diagnosis and management of GERD; however, these have not been comprehensively discussed in the recent radiology literature. Understanding the role of imaging in GERD and its complications is important to aid in multidisciplinary treatment of GERD. GERD results from prolonged or recurrent reflux of gastric contents into the esophagus. Common symptoms include heartburn or regurgitation. Prolonged reflux of gastric contents into the esophagus can cause erosive esophagitis. Over time, the inflammatory response related to esophagitis can lead to deposition of fibrous tissue and development of strictures. Alternatively, the esophageal mucosa can undergo metaplasia (Barrett esophagus), a precursor to dysplasia (which can lead to adenocarcinoma). Conventional barium esophagography has long been considered the primary imaging modality for the esophagus, and the fluoroscopic findings for diagnosis of GERD have been well established. Multimodality imaging has a clear role in detection and assessment of the complications of GERD, specifically reflux esophagitis and Barrett esophagus; differentiation of benign and malignant strictures; and detection, staging, and posttreatment surveillance of esophageal adenocarcinoma. Given the dramatic changes in utilization of abdominal imaging during the past 2 decades, with significantly declining volume of fluoroscopic procedures and concomitant increase in CT and MRI studies, it is crucial that modern radiologists appreciate the value of barium esophagography in the workup of GERD and recognize the key imaging features of GERD and its complications at CT and MRI.

Nonepithelial Neoplasms of the Pancreas, Part 2: Malignant Tumors and Tumors of Uncertain Malignant Potential From the Radiologic Pathology Archives.

Almost all neoplasms of the pancreas are derived from pancreatic epithelial components, including the most common pancreatic mass, primary pancreatic ductal adenocarcinoma (PDAC). Nonepithelial neoplasms comprise only 1%-2% of all pancreatic neoplasms. Although some may arise directly from intrapancreatic elements, many originate from mesenchymal, hematopoietic, or neural elements in the retroperitoneal peripancreatic space and grow into the pancreas. Once these tumors reach a certain size, it can be challenging to identify their origin. Because these manifest at imaging as intrapancreatic masses, awareness of the existence and characteristic features of these nonepithelial neoplasms is crucial for the practicing radiologist in differentiating these tumors from primary epithelial pancreatic tumors, an important distinction given the vastly different management and prognosis. In part 1 of this article, the authors reviewed benign nonepithelial neoplasms of the pancreas. This article focuses on malignant nonepithelial neoplasms and those of uncertain malignant potential that can be seen in the pancreas. The most common malignant or potentially malignant nonepithelial pancreatic tumors are of mesenchymal origin and include soft-tissue sarcomas, solitary fibrous tumor, and inflammatory myofibroblastic tumor. These tumors commonly manifest as large heterogeneous masses, often containing areas of necrosis and hemorrhage. The clinical features associated with these tumors and the imaging characteristics including enhancement patterns and the presence of fat or calcification help distinguish these tumors from PDAC. Hematopoietic tumors, including lymphoma and extramedullary plasmacytoma, can manifest as isolated pancreatic involvement or secondarily involve the pancreas as widespread disease. Hyperenhancing paragangliomas or hypervascular metastatic disease can mimic primary pancreatic neuroendocrine tumors or vascular anomalies.

Pembrolizumab in patients with thymic carcinoma: a single-arm, single-centre, phase 2 study.

BACKGROUND: Treatment options are limited for patients with thymic carcinoma. These aggressive tumours are not typically associated with paraneoplastic autoimmune disorders, and strong PD-L1 expression has been reported in thymic epithelial tumours. We aimed to assess the activity of pembrolizumab, a monoclonal antibody that targets PD-1, in patients with advanced thymic carcinoma. METHODS: We completed a single-arm phase 2 study of pembrolizumab in patients with recurrent thymic carcinoma who had progressed after at least one line of chemotherapy. This was a single-centre study performed at Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC, USA. Key inclusion criteria were an Eastern Cooperative Oncology Group performance status of 0-2, no history of autoimmune disease or other malignancy requiring treatment or laboratory abnormality, and adequate organ function. Patients received 200 mg of pembrolizumab every 3 weeks for up to 2 years. The primary objective of the study was the proportion of patients who had achieved a response assessed with Response Evaluation Criteria in Solid Tumors version 1.1. Analysis was per protocol, in all eligible patients. The study is registered with ClinicalTrials.gov, number NCT02364076, and is closed to accrual; we report the final analysis. FINDINGS: 41 patients were enrolled from March 12, 2015, to Dec 16, 2016, of whom 40 were eligible and evaluable and one was excluded because of elevated liver enzymes at screening. The median follow-up was 20 months (IQR 14-26). The proportion of patients who achieved a response was 22·5% (95% CI 10·8-38·5); one (3%) patient achieved a complete response, eight (20%) patients achieved partial responses, and 21 (53%) patients achieved stable disease. The most common grade 3 or 4 adverse events were increased aspartate aminotransferase and alanine aminotransferase (five [13%] patients each). Six (15%) patients developed severe autoimmune toxicity, including two (5%) patients with myocarditis. There were 17 deaths at the time of analysis, but no deaths due to toxicity. INTERPRETATION: Pembrolizumab is a promising treatment option in patients with thymic carcinoma. Because severe autoimmune disorders are more frequent in thymic carcinoma than in other tumour types, careful monitoring is essential. FUNDING: Merck & Co.

Primary Hepatic Neoplasms of Vascular Origin: Key Imaging Features and Differential Diagnoses With Radiology-Pathology Correlation.

OBJECTIVE: This article describes, illustrates, and correlates imaging and pathologic features of primary vascular mesenchymal neoplasms of the liver, which arise from the vascular endothelium and perivascular epithelioid cells. CONCLUSION: Familiarity with the spectrum of benign, malignant-potential and malignant vascular neoplasms, and nonneoplastic mimickers allows consideration in the differential diagnosis of enhancing hepatic masses. Understanding relevant pathologic features facilitates recognition of key imaging features, specifically dynamic contrast enhancement patterns on CT and MRI, which provide a useful classification system.

Soft-Tissue Sarcomas of the Abdomen and Pelvis: Radiologic-Pathologic Features, Part 2-Uncommon Sarcomas.

Soft-tissue sarcomas occurring in the abdomen and pelvis are an uncommon but important group of malignancies. Recent changes to the World Health Organization classification of soft-tissue tumors include the movement of gastrointestinal stromal tumors (GISTs) into the soft-tissue tumor classification. GIST is the most common intraperitoneal sarcoma. Liposarcoma is the most common retroperitoneal sarcoma, and leiomyosarcoma is the second most common. GIST, liposarcoma, and leiomyosarcoma account for the majority of sarcomas encountered in the abdomen and pelvis and are discussed in part 1 of this article. Undifferentiated pleomorphic sarcoma (previously called malignant fibrous histiocytoma), dermatofibrosarcoma protuberans, solitary fibrous tumor, malignant peripheral nerve sheath tumor, rhabdomyosarcoma, extraskeletal chondro-osseous sarcomas, vascular sarcomas, and sarcomas of uncertain differentiation uncommonly arise in the abdomen and pelvis and the abdominal wall. Although these lesions are rare sarcomas and their imaging features overlap, familiarity with the locations where they occur and their imaging features is important so they can be diagnosed accurately. The anatomic location and clinical history are important factors in the differential diagnosis of these lesions because metastasis, more-common sarcomas, borderline fibroblastic proliferations (such as desmoid tumors), and endometriosis have imaging findings that overlap with those of these uncommon sarcomas. In this article, the clinical, pathologic, and imaging findings of uncommon soft-tissue sarcomas of the abdomen and pelvis and the abdominal wall are reviewed, with an emphasis on their differential diagnosis.

Soft-Tissue Sarcomas of the Abdomen and Pelvis: Radiologic-Pathologic Features, Part 1-Common Sarcomas: From the Radiologic Pathology Archives.

Soft-tissue sarcomas are a diverse group of rare mesenchymal malignancies that can arise at any location in the body and affect all age groups. These sarcomas are most common in the extremities, trunk wall, retroperitoneum, and head and neck. In the adult population, soft-tissue sarcomas arising in the abdomen and pelvis are often large masses at the time of diagnosis because they are usually clinically silent or cause vague or mild symptoms until they invade or compress vital organs. In contrast, soft-tissue sarcomas arising from the abdominal wall come to clinical attention earlier in the course of disease because they cause a palpable mass, abdominal wall deformity, or pain that is more clinically apparent. The imaging features of abdominal and pelvic sarcomas and abdominal wall sarcomas can be nonspecific and overlap with more common pathologic conditions, making diagnosis difficult or, in some cases, delaying diagnosis. Liposarcoma (well-differentiated and dedifferentiated liposarcomas), leiomyosarcoma, and gastrointestinal stromal tumor (GIST) are the most common intra-abdominal primary sarcomas. Any soft-tissue sarcoma can arise in the abdominal wall. Knowledge of the classification and pathologic features of soft-tissue sarcomas, the anatomic locations where they occur, and their cross-sectional imaging features helps the radiologist establish the diagnosis or differential diagnosis so that patients with soft-tissue sarcomas can receive optimal treatment and management. In part 1 of this article, the most common soft-tissue sarcomas (liposarcoma, leiomyosarcoma, and GIST) are reviewed, with a discussion on anatomic locations, classification, clinical considerations, and differential diagnosis. Part 2 will focus on the remainder of the soft-tissue sarcomas occurring in the abdomen and pelvis.

Gastrointestinal Lymphoma: Radiologic-Pathologic Correlation.

Extranodal lymphoma is a heterogeneous group of hematologic neoplasms that can affect every abdominal organ, with distinctive pathologic, radiologic, and clinical features. The radiologic findings are closely related to the underlying pathophysiology, and an understanding of these characteristic features should facilitate recognition of extranodal lymphoma and its various subtypes. Within the abdomen, lymphoma is found most commonly in the gastrointestinal tract, especially the stomach. This article presents the findings in gastrointestinal tract lymphoma.

Exceptional Response to Systemic Therapy in Advanced Metastatic Gastric Cancer: A Case Report.

Gastroesophageal adenocarcinomas represent one of the top five most common types of cancer worldwide. Despite significant advancement, it is still not known which first-line chemotherapy option is best matched to an individual patient. The vast advances in molecular biology have led to the discovery of many potential predictive biomarkers, such as HER-2 neu, thymidylate synthase (TS), excision repair cross-complementation group 1 (ERCC1), and topoisomerase-1 (TOPO1). These markers could allow us to select treatment based on an individual's tumor profile, resulting in an improvement of outcome. Our report highlights two patients with metastatic gastric cancer that achieved an exceptional response with traditional therapy and provides insights into the future perspectives of molecular profile-directed chemotherapy.

Nonepithelial Neoplasms of the Pancreas: Radiologic-Pathologic Correlation, Part 1--Benign Tumors: From the Radiologic Pathology Archives.

Solid and cystic pancreatic neoplasms are being recognized more frequently with increasing utilization and spatial resolution of modern imaging techniques. In addition to the more common primary pancreatic solid (ductal adenocarcinoma) and cystic neoplasms of epithelial origin, nonepithelial neoplasms of the pancreas may appear as well-defined solid or cystic neoplasms. Most of these lesions have characteristic imaging features, such as a well-defined border, which allows differentiation from ductal adenocarcinoma. Solid masses include neurofibroma, ganglioneuroma, leiomyoma, lipoma, and perivascular epithelioid cell tumor (PEComa). Schwannomas and desmoid tumors can be solid or cystic. Cystic tumors include mature cystic teratoma and lymphangioma. Lipoma, PEComa, and mature cystic teratoma can contain fat, and ganglioneuroma and mature cystic teratoma may contain calcification. Although these unusual benign neoplasms are rare, the radiologist should at least consider them in the differential diagnosis of well-defined lesions of the pancreas. The goal of this comprehensive review is to improve understanding of these rare primary pancreatic mesenchymal tumors.

From the radiologic pathology archives: gastrointestinal lymphoma: radiologic and pathologic findings.

Gastrointestinal (GI) lymphoma encompasses a heterogeneous group of neoplasms that have a common lymphoid origin but variable pathologic and imaging features. Extranodal marginal zone B-cell lymphoma (ENMZL) and diffuse large B-cell lymphoma (DLBCL) are the most common. ENMZL usually occurs in the stomach, where it is associated with chronic infection by Helicobacter pylori, and is typically a superficial spreading lesion that causes mucosal nodularity or ulceration and mild wall thickening. DLBCL may arise de novo or from transformation of ENMZL or other low-grade lymphomas. This form of lymphoma produces extensive wall thickening or a bulky mass, but obstruction is uncommon. Mantle cell lymphoma is the classic cause of lymphomatous polyposis, but multiple polyps or nodules can also be seen with ENMZL and follicular lymphoma. Burkitt lymphoma is usually characterized by an ileocecal mass or wall thickening in the terminal ileum in young children, often in the setting of widespread disease. Primary GI Hodgkin lymphoma, which is rare, may be manifested by a variety of findings, though stenosis is more common than with non-Hodgkin lymphoma. Enteropathy-associated T-cell lymphoma is frequently associated with celiac disease and is characterized by wall thickening, ulceration, and even perforation of the jejunum. Accurate radiologic diagnosis of GI lymphoma requires a multifactorial approach based on the clinical findings, site of involvement, imaging findings, and associated complications.

National ultrasound curriculum for medical students.

Ultrasound (US) is an extremely useful diagnostic imaging modality because of its real-time capability, noninvasiveness, portability, and relatively low cost. It carries none of the potential risks of ionizing radiation exposure or intravenous contrast administration. For these reasons, numerous medical specialties now rely on US not only for diagnosis and guidance for procedures, but also as an extension of the physical examination. In addition, many medical school educators recognize the usefulness of this technique as an aid to teaching anatomy, physiology, pathology, and physical diagnosis. Radiologists are especially interested in teaching medical students the appropriate use of US in clinical practice. Educators who recognize the power of this tool have sought to incorporate it into the medical school curriculum. The basic question that educators should ask themselves is: "What should a student graduating from medical school know about US?" To aid them in answering this question, US specialists from the Society of Radiologists in Ultrasound and the Alliance of Medical School Educators in Radiology have collaborated in the design of a US curriculum for medical students. The implementation of such a curriculum will vary from institution to institution, depending on the resources of the medical school and space in the overall curriculum. Two different examples of how US can be incorporated vertically or horizontally into a curriculum are described, along with an explanation as to how this curriculum satisfies the Accreditation Council for Graduate Medical Education competencies, modified for the education of our future physicians.

Imaging of whole-organ pancreas transplants.

Whole pancreas transplantation is an established treatment for selected patients with diabetic nephropathy or poorly controlled diabetes. Surgical techniques vary and have evolved over the past 4 decades. Imaging evaluation of the whole-pancreas transplant should begin with an understanding of the most commonly used surgical techniques and the spectrum of postoperative complications. Ultrasonography (US) should be the first-line modality in evaluating the pancreas allograft and vasculature. Computed tomography (CT) is useful in the assessment of extra-allograft processes, particularly in ruling out abscess formation or evaluating suspected bowel complications. Magnetic resonance (MR) imaging is reserved for cases in which complete evaluation with US or CT is not possible. MR angiography can help provide an accurate assessment of vascular abnormalities. The radiologist must be familiar with the spectrum of surgical techniques and the normal postoperative imaging appearances of the whole-pancreas transplant so as to be able to recognize abnormal postoperative findings. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg.322115144/-/DC1.

Testicular epidermoid cysts: sonographic features with clinicopathologic correlation.

OBJECTIVE: The purpose of this series was to describe the sonographic features of intratesticular epidermoid cysts with clinicopathologic correlation. METHODS: A retrospective review of the sonographic features of all intratesticular epidermoid cysts within the radiologic pathology archive of the Armed Forces Institute of Pathology with correlation with clinical, surgical, and pathologic data was performed. On sonograms, intratesticular epidermoid cysts were evaluated for shape, borders, and the presence of characteristic features, including alternating hypoechoic and hyperechoic rings, mural calcifications, and echogenic central core. Color Doppler imaging was evaluated for the presence of internal flow. RESULTS: Of 21 cysts seen in 20 male patients (mean age, 24 years; range, 11-52 years), the most common finding was mural calcifications, which were seen in 18 lesions (86%). Concentric rings of alternating echogenicity were shown in 13 lesions (62%), and 7 cysts (33%) had an echogenic central core. No cysts showed internal vascularity. CONCLUSIONS: Testicular epidermoid cysts are uncommon solid-appearing testicular masses that usually present as palpable masses and are benign. Knowledge of the sonographic and pathologic features may help differentiate these lesions from malignancy and possibly prevent unnecessary orchiectomy.