Articles

Articles are a collaborative effort to provide a single canonical page on all topics relevant to the practice of radiology. As such, articles are written and edited by countless contributing members over a period of time. A global group of dedicated editors oversee accuracy, consulting with expert advisers, and constantly reviewing additions.

888 results found
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Kaposi sarcoma

Kaposi sarcoma is a low-to-intermediate grade mesenchymal tumor that involves the lymphovascular system. The tumor can involve the pulmonary, gastrointestinal, cutaneous and musculoskeletal systems. Pathology There are four recognized variants 1: classic (chronic): multiple distal lower extre...
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Kimura disease

Kimura disease, also known as eosinophilic hyperplastic lymphogranuloma, is a rare benign inflammatory disease that characteristically manifests as enlargement of cervical lymph nodes and salivary glands. Epidemiology Kimura disease typically affects males (80%) between 20 and 40 years of age ...
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KRAS mutation

KRAS (shortened name for the gene Kirsten RAt Sarcoma viral oncogene homolog) mutations are associated in a number of malignancies including:  certain adenocarcinomas of the lung colorectal carcinoma 1 pancreatic ductal adenocarcinoma Several germline KRAS mutations have also been found to b...
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Krenning score of neuroendocrine tumor uptake

The Krenning score is a proposed semi-quantitative method of assessing the degree of tracer uptake on octreotide scintigraphy. Parameters Initially designed for assessment of 111In-DTPA on planar imaging, the Krenning score is applicable to SPECT or PET/CT using various radiopharmaceuticals. ...
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Labeled imaging anatomy cases

This article lists a series of labeled imaging anatomy cases by system and modality. Brain CT head: non-contrast axial CT head: non-contrast coronal CT head: non-contrast sagittal CT head: angiogram axial CT head: angiogram coronal CT head: angiogram sagittal CT head: venogram axial CT ...
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Lactate dehydrogenase

Lactate dehydrogenase (LDH or LD) is a key enzyme in most cells, catalyzing the reversible conversion of pyruvate to L-lactate. Its contemporaneous main clinical uses are limited primarily to the investigation of hemolysis, serous collections and as a tumor marker. Physiology L-lactate dehydro...
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Lambert-Eaton myasthenic syndrome

Lambert-Eaton myasthenic syndrome (LEMS) is a rare neuromuscular junction disorder of paraneoplastic or primary autoimmune etiology. Epidemiology LEMS is the second most common neuromuscular junction disease after myasthenia gravis.  Two-thirds of LEMS present as a paraneoplastic syndrome sec...
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Langerhans cell histiocytosis (skeletal manifestations)

The skeleton is the most commonly involved organ system in Langerhans cell histiocytosis (LCH) and is by far the most common location for single-lesion LCH, often referred to as eosinophilic granuloma (EG) (the terms are used interchangeably in this article). For a general discussion of this dis...
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Large-cell lung cancer

Large-cell lung cancer is one of the histological types of non-small-cell carcinomas of the lung diagnosed only on resection, after exclusion of adenocarcinomatous or squamous differentiation.  Epidemiology It is thought to account for approximately 10% of bronchogenic carcinoma 1. Clinical p...
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Large cell neuroendocrine carcinoma of the lung

Large cell neuroendocrine carcinoma (LCNEC) of the lung is classified as a subtype of large cell carcinoma of the lung. It is also classified as a pulmonary neuroendocrine tumor. Epidemiology The incidence peaks around the 6th decade 6. There is an increased male predilection 7. They are rare ...
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Laryngeal carcinoma (staging)

Laryngeal carcinoma staging refers to TNM staging of carcinomas involving the supraglottic, glottic, and subglottic larynx. The vast majority of applicable cases are squamous cell carcinomas, but other epithelial tumors are also included. The following article reflects the 8th edition published ...
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Leiomyoma

Leiomyoma is a benign smooth muscle (myometrial) tumor, most commonly found in the uterus.  Classification Leiomyoma is classified by location: uterine leiomyoma cervical leiomyoma leiomyoma of the urinary bladder urethral leiomyoma solitary cutaneous leiomyoma vascular leiomyoma (angiol...
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Leiomyosarcoma

Leiomyosarcomas are extremely rare malignant neoplasms that originate from smooth muscle cells and may be considered the malignant counterpart of a leiomyoma. They are classified as a soft tissue tumor and account for ~8% of malignant soft tissue tumors 10. Pathology Location  Leiomyosarcomas...
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Leiomyosarcoma of the prostate

Leiomyosarcoma of the prostate is a rare mesenchymal smooth muscle malignancy of the prostate gland. Epidemiology It is a rare tumor with less than 200 cases reported in the literature accounting for approximately 25% of all sarcomas of the prostate gland and less than 0.1% of primary prostate...
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Lepidic growth

Lepidic growth is a pathological term referring to a pattern of cell proliferation along the lining of the alveolar structures of the lung as is seen in a subset of lung tumors 1. History and etymology ‘lepidic’ was coined by the English pathologist John George Adam (1862-1926) whilst at McGil...
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Lepidic-predominant adenocarcinoma of the lung

Lepidic-predominant adenocarcinoma (LPA) of the lung, formerly known as non-mucinous bronchoalveolar carcinoma, is a subtype of invasive adenocarcinoma of the lung characterized histologically when the lepidic component comprises the majority of the lesion. Terminology The category of 'lepid p...
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Leptomeningeal enhancement

Leptomeningeal enhancement refers to a diffuse or focal gyriform or serpentine enhancement that can be seen in the following conditions: Diffuse meningitis pyogenic meningitis viral meningitis tuberculous meningitis (can also be focal) CNS cryptococcal infection coccidioidal meningitis (c...
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Leptomeningeal metastases

Leptomeningeal metastases, also known as carcinomatous meningitis, refers to the spread of malignant cells through the CSF space. These cells can originate from primary CNS tumors (e.g. drop metastases), as well as from distant tumors that have metastasized via hematogenous spread. This article...
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Leser-Trélat sign

The Leser-Trélat sign is a dermatological paraneoplastic syndrome referring to the explosive and rapid eruption of multiple seborrheic keratoses. It is associated with a number of different cancers including adenocarcinoma (e.g. gastric, colorectal), breast cancer, and lymphoproliferative disord...
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Leukemia

Leukemia is a hematological neoplasm characterized by the overproduction of immature (blasts) or abnormally differentiated cells of the hematopoietic system in the bone marrow that often, but not always, extends into the peripheral blood.  This article aims to provide an overview of leukemia as...
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Leukemia (CNS manifestations)

Leukemia CNS manifestations can be divided into those related to the disease itself and those associated with its treatment. Leukaemias are hematologic malignancies in which occur a proliferation of hematopoietic cells at an undifferentiated or partially differentiated stage of maturation. CNS ...
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Leukostasis

Leukostasis, also known as symptomatic hyperleukocytosis, is a medical emergency in patients with leukemia, particularly acute myeloid leukemia (AML) and in the blast phase of chronic myeloid leukemia (CML), characterized by the over-accumulation of leukemic cells within the small vessels. Altho...
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Lhermitte-Duclos disease

Lhermitte-Duclos disease, also known as dysplastic cerebellar gangliocytoma, is a rare tumor of the cerebellum. It is probably hamartomatous, although the exact pathogenesis remains unknown 2,6. Even though it may not be neoplastic, it is considered a WHO grade I tumor in the current WHO classif...
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Lichen planus

Lichen planus refers to a dermatological condition that typically affects the skin, nails, oral cavity, genitals or perineum. Skin lesions are characterized by violaceous scaly pruritic plaque eruption while oral lesions are characterized by erosions and lace-like reticular plaques. It is a chr...
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Lipoblastoma

Lipoblastoma is a rare, benign, encapsulated tumor arising from embryonic white fat. Epidemiology It occurs primarily in infancy and early childhood (more than 90% before age 3 years). Clinical presentation May present as a rapidly enlarging mass 4. It most often occurs in the extremities an...
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Lipofibromatosis

Lipofibromatosis refers to a rare unspecified/borderline slow-growing soft tissue tumor prone to recurrence, which is often found in the hands and feet of children. Terminology Infantile or juvenile fibromatosis variant is an alternative term, which has been used but is now discouraged 1. Ep...
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Lipoma vs well-differentiated liposarcoma

There a number of features that can help distinguish between lipoma and well-differentiated liposarcoma. This article relates to superficial well-differentiated liposarcomas that typically occur in the extremities, also known as atypical lipomatous tumors, and not retroperitoneal liposarcoma. E...
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Liposclerosing myxofibrous tumor

Liposclerosing myxofibrous tumors (LSMFT), also known as polymorphic fibro-osseous lesions of bone, are rare benign fibro-osseous lesions that have a predilection for the intertrochanteric region of the femur. Clinical presentation It is slightly more common in males with mean age of 30-40 yea...
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LI-RADS

Liver Imaging Reporting and Data System (LI-RADS) is both a set of standardized terminology and a classification system for imaging findings in liver lesions. The LI-RADS score for a liver lesion is an indication of its relative risk for hepatocellular carcinoma (HCC). The classification system...
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Littoral cell angioma of the spleen

Littoral cell angioma of the spleen is a rare, benign primary vascular tumor of the spleen. Epidemiology Littoral cell angiomas may occur at any age and have no gender predilection. Associations Littoral cell angiomas have been diagnosed in association with various malignancies outside the s...
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Liver tumors

Liver tumors, like tumors of any organ, can be classified as primary or secondary. Metastases Liver metastases are by far the most common hepatic malignancy, with many of the most common primaries readily seeding to the liver. This is especially the case with gastrointestinal tract tumors, due...
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Lobectomy (lung)

A lobectomy (plural: lobectomies) is the complete resection of one lobe of the lung and is the commonest lung surgery performed for bronchogenic carcinoma. Technique A posterolateral thoracotomy is the commonest approach for the resection of lung malignancies. For other surgical approaches for...
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Lobular breast carcinoma

Lobular breast carcinoma is a subtype of breast cancer can range from lobular carcinoma in situ (LCIS) to invasive lobular carcinoma. Pathology Multicentricity and bilaterality tend to be quite common with lobular breast carcinomas.
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Lobular carcinoma in situ

Lobular carcinoma in situ (LCIS) represents the next step up from atypical lobular hyperplasia (ALH) along the malignant spectrum of lobular breast carcinoma. Epidemiology Lobular carcinoma in situ occurs predominantly in premenopausal women with a mean age of 45 years old, approximately 10-15...
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Lollipop sign (hepatic epithelioid hemangioendothelioma)

The lollipop sign is seen in hepatic epithelioid hemangioendothelioma (HEHE). It represents hepatic/portal vein and/or their tributaries/branches tapering and terminating at or just within the edge of a well defined peripherally enhancing (or non-enhancing) lesion with an avascular core on CT or...
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Lower limb lymph nodes

The lower limb lymph nodes consist of the: inguinal lymph nodes superficial inguinal lymph nodes deep inguinal lymph nodes popliteal lymph nodes
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Low-grade appendiceal mucinous neoplasm

Low-grade appendiceal mucinous neoplasms (LAMN), previously known as appendiceal mucinous cystadenomas, are rare mucinous tumors of the appendix showing low-grade cytologic atypia, c.f. high-grade appendiceal mucinous neoplasms. Terminology  Considerable controversy still exists on mucinous ne...
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Low-grade fibromyxoid sarcoma

Low-grade fibromyxoid sarcomas are malignant fibroblastic soft tissue neoplasms characterized by alternating fibrous and myxoid elements and a propensity to late recurrence and metastasis. Terminology An alternative term for low-grade fibromyxoid sarcoma is Evans tumor. The term hyalinizing sp...
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Low-grade myofibroblastic sarcoma

Low-grade myofibroblastic sarcomas are locally aggressive rarely metastasizing fibroblastic tumors. Terminology Another acceptable term for low-grade myofibroblastic sarcoma is myofibrosarcoma 1. Epidemiology Low-grade myofibroblastic sarcomas most commonly occur in adults in the 4th and 5t...
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Lucent/lytic bone lesion - differential diagnosis (mnemonic)

Mnemonics for the differential diagnosis of lucent/lytic bone lesions include: FEGNOMASHIC FOG MACHINES They are anagrams of each other and therefore include the same components. They are by no means exhaustive lists, but are a good start for remembering a differential for a lucent/lytic bone...
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Lugano classification (lesion measurement guidelines)

The Lugano classification is a lymphoma staging system resulting from recommended changes in 2011 to the Cotswolds modified Ann Arbor staging. This article outlines the lesion measurement guidelines for the system: Eligible lesions lymph nodes: the longest diameter in axial plane should be >1....
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Lugano classification (PET-CT treatment response)

The Lugano classification is a lymphoma staging system for non-Hodgkin and Hodgkin lymphoma. This article outlines the classification's response to treatment based on PET-CT.  Also included in the classification are staging and response to treatment based on CT. Scoring system The Lugano clas...
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Lugano classification (response to treatment on CT)

The Lugano classification is a lymphoma staging system resulting from recommended changes in 2011 to the Ann Arbor staging with Cotswolds modifications. This article outlines the classification's response to treatment based on CT.  Also included in the classification are staging and reponse to ...
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Lugano staging classification

The Lugano staging classification is the lymphoma staging system that is most commonly used in clinical practice currently. The categories for initial staging are defined in this article. See separate articles for the Lugano criteria for response assessment by PET-CT or by CT alone, as well as g...
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Lung cancer

Lung cancer (primary lung cancer), or frequently if somewhat incorrectly known as bronchogenic carcinoma, is a broad term referring to the main histological subtypes of primary lung malignancies that are mainly linked with inhaled carcinogens, with cigarette smoke being a key culprit.  This art...
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Lung cancer (staging - IASLC 7th edition - superseded)

The IASLC (International Association for the Study of Lung Cancer) 7th edition lung cancer staging system was proposed in 2010 and has now been updated and superseded by the 8th edition, published in 2016. Small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC) used to be staged di...
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Lung cancer (staging - IASLC 8th edition)

The IASLC (International Association for the Study of Lung Cancer) 8th edition lung cancer staging system was introduced in 2016 and supersedes the IASLC 7th edition.  Standard-of-care lung cancer staging ideally should be performed in a multidisciplinary meeting using the information provided ...
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Lung carcinomas of the salivary gland type

Lung carcinomas of the salivary gland type are also known as salivary gland–type tumors of the lung (SGTTLs) or bronchial gland neoplasms.  The usual consignation to the group of non-small cell lung cancer (NSCLC) may be unfortunate because the clinical behavior of SGTTLs can be quite different...
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Lung carcinosarcoma

Lung carcinosarcomas are uncommon malignant biphasic tumors classified as a subtype of sarcomatoid tumors of the lung.  Epidemiology It is rare and thought to account for <1% of all lung cancers. There may be a greater male predilection with tumor generally occurring heavy smokers with peak oc...
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Lung surgery

Lung (or pulmonary) surgery is most frequently performed for lung carcinoma, and encompasses a broad spectrum of procedures: sublobar resections wedge resection segmentectomy lobectomy: commonest surgery for bronchogenic carcinoma includes sleeve lobectomy and bilobectomy pneumonectomy Te...
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Lymphangitic carcinomatosis

Lymphangitic carcinomatosis, or lymphangitis carcinomatosa, is the term given to tumor spread through the lymphatics of the lung and is most commonly seen secondary to adenocarcinoma. Epidemiology The demographics will reflect that of the underlying malignancy (see below). Clinical presentati...
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Lymph node enlargement

Lymph node enlargement (rarely lymphadenomegaly) is often used synonymously with lymphadenopathy, which is not strictly correct. Terminology Lymphadenopathy (or adenopathy) is, if anything, a broader term, referring to any pathology of lymph nodes, not necessarily resulting in increased size; ...
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Lymphedema

Lymphedema is the pathologic accumulation of fluid in the soft tissues as the result of impaired lymphatic drainage, with resultant inflammation, adipose tissue hypertrophy, and fibrosis. It can be either primary or secondary, due to surgery or disease processes. The condition can cause disfigur...
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Lymphoma

Lymphoma (historically lymphosarcoma was used for diffuse forms of the disease) is a malignancy arising from lymphocytes or lymphoblasts. Lymphoma can be restricted to the lymphatic system or can arise as extranodal disease. This, along with variable aggressiveness results in a diverse imaging a...
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Lymphoma of the spinal cord

Lymphoma of the spinal cord is an uncommon manifestation of lymphoma. Although lymphoma more commonly involves the vertebral body (vertebral body tumors) or epidural compartment, intramedullary lymphoma may rarely occur.   Apparent intramedullary spinal cord lymphoma may often, in fact, represe...
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Lymphoma of the uterine cervix

Lymphoma of the uterine cervix is generally uncommon and when it does occur tends to present as cervical involvement with added background multi-organ disease rather than isolated primary cervical lymphoma 1. It is often considered part of the spectrum of uterine lymphoma. Epidemiology In the ...
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Lymphoma (staging)

Many lymphoma staging systems for both Hodgkin lymphoma and non-Hodgkin lymphoma have been developed. The most widely used currently is the Lugano staging classification, which also separately defines criteria for response to treatment assessed by PET-CT or by CT alone. Patients having undergon...
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Lymphomatoid granulomatosis (CNS manifestations)

Lymphomatoid granulomatosis of the central nervous system is uncommon, but represents the second most common site of involvement in patients with systemic lymphomatoid granulomatosis, after the lungs, which are most commonly involved. It is considered one of the immunodeficiency-associated CNS l...
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Lymphoscintigraphy

Lymphoscintigraphy is a nuclear medicine technique to visualize regional lymphatic drainage, especially for mapping sentinel lymph nodes, from a site of radiopharmaceutical injection. Radiopharmaceutical Colloidal agents are used as these particles enter lymphatic channels and migrate to lymph...
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Magnetic resonance lymphangiography

Magnetic resonance lymphangiography (MRL) is an imaging technique used to visualize and map the lymphatic vessels. The technique is used for treatment planning in supermicrosurgical procedures, including lymphaticovenous anastomosis, lymphaticolymphatic bypass and vascularized lymph node transfe...
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Male breast cancer

Male breast cancer is exceptionally rare and only accounts for less than 0.25% of male malignancies and ~0.5-1% of all breast cancer (both genders). The diagnosis is sometimes delayed due to the patient's hesitancy to seek advice. Workup from a radiological point of view is the same as for women...
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Male breast disease

Male breast disease includes a wide spectrum of conditions. Many conditions and entities that affect the female breast may also affect the male breast.  Pathology Malignant male breast cancer lymphoma dermatofibrosarcoma Benign gynecomastia pseudogynecomastia: fat deposition within the b...
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Malignant biliary tract obstruction (summary)

This is a basic article for medical students and other non-radiologists Malignant biliary tract obstruction (MBTO) represents a group of conditions that cause obstructive jaundice. While most examples are the result of pancreatic head cancers, other malignancies may be causative. Reference art...
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Malignant liver tumors (pediatric)

Pediatric malignant liver tumors are rare, some of which occur only in children but that are similar to those that occur in adults. Epidemiology Malignant liver tumors account for ~1% of pediatric malignancies 2. Pathology Broadly, any malignant liver mass can be defined as a metastasis or p...
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Malignant melanoma

Malignant melanoma is a malignant neoplasm that arises from melanocytes (or cells that derive from melanocytes).   Pathology Melanocytes predominantly occur in the basal layer of the epidermis and most melanomas, therefore, arise in the skin.  However, melanocytes do occur in other locations a...
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Malignant mixed Mullerian tumor of the uterus

Malignant mixed Müllerian tumor (MMMT) of the uterus, also known as uterine carcinosarcoma, is the commonest (up to 50%) type of uterine sarcoma. They are thought to account for 2-8% of all malignant uterine cancers 1-2. The uterus is the commonest site for malignant mixed Müllerian tumors 1.  ...
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Malignant neoplasms involving the uterus

Malignant neoplasms involving the uterus account for a significant proportion of all female cancers. They can be classified as: endometrial carcinoma : commonest: >90% of all uterine malignancies endometrioid carcinoma of the uterus: commonest histological type, ~80% papillary serous carcino...
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Malignant peritoneal mesothelioma

Malignant peritoneal mesothelioma is an uncommon primary tumor of the peritoneal lining. It shares epidemiological and pathological features with - but is less common than - its pleural counterpart, which is described in detail in the general article on mesothelioma. Other abdominal subtypes (al...
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Malignant pleural disease

Malignant pleural disease usually heralds a poor prognosis, whether it represents a primary pleural malignancy or metastatic involvement.  Clinical presentation Clinical presentation is variable. Patients may be asymptomatic or have pleuritic pain. If associated with a sizable pleural effusion...
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Malignant pleural mesothelioma (TNM staging)

Below is the eighth edition of the TNM staging system for malignant pleural mesothelioma, which was published in 2018 1. T - Tumor Tx: primary tumor cannot be assessed T0: no evidence of primary tumor T1 involving ipsilateral parietal pleura (inc. mediastinal and diaphragmatic pleura) +/- v...
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Malignant transformation

Malignant transformation is the term given to the process whereby either normal, metaplastic, or benign neoplastic tissue, becomes a cancer. The process usually occurs in a series of steps and the affected tissue gradually accumulates the genetic mutations that express a malignant phenotype. The...
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MALT lymphoma

Mucosa-associated lymphoid tissue (MALT) lymphoma, also called extranodal marginal zone B-cell lymphoma, is a type of low-grade extranodal lymphoma.  Epidemiology MALT lymphoma represents ~7.5% of non-Hodgkin lymphomas. The average age of presentation is 60 years with a slight female predomina...
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MALT lymphoma (dura)

MALT lymphomas of the dura (also known as extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue of the dura), are an uncommon form of CNS lymphoma, accounting for an even smaller proportion of dural masses. They are, however, the most common form of primary dural lymphoma.  Unl...
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Mammalian target of rapamycin

The mammalian target of rapamycin (mTOR), also known as mechanistic target of rapamycin, are two proteins that are involved in cell signaling pathways implicated in tumorigenesis. The mTOR proteins are serine/threonine protein kinases that combine with several other proteins to form two large c...
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Mandibular lesions

Mandibular lesions are myriad and common. The presence of teeth results in lesions that are specific to the mandible (and maxilla) and a useful classification that defines them as odontogenic or non-odontogenic. While it may often not be possible to make a diagnosis on imaging alone, this classi...
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Mantle cell lymphoma

Mantle cell lymphoma (MCL) is a type of non-Hodgkin lymphoma (NHL) and accounts for ~5% of all NHL. It is a malignant neoplasm of virgin B cells that closely resemble normal mantle zone B cells surrounding germinal centers. Epidemiology They occur in older adults (mean age ~60 years), and ther...
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Masaoka staging system of thymoma

The Masaoka staging system is commonly adopted for thymomas 1-3, and is the most important determinant of survival following surgical resection 4: stage I: intact thymic capsule stage II: capsular invasion into adjacent mediastinal fat or pleura stage III: macroscopic invasion into adjacent o...
Article

Mass-forming intrahepatic cholangiocarcinoma

Mass-forming intrahepatic cholangiocarcinomas (MF-ICC), also referred as peripheral cholangiocarcinomas, comprise one of the three recognized growth patterns of intrahepatic cholangiocarcinomas.  On imaging, these tumors usually present as large and relatively well-defined hepatic masses with l...
Article

Maxillary antral carcinoma

Maxillary antral carcinomas are an uncommon head and neck malignancy. They usually present late despite growing large since they remain confined to the maxillary sinus and produce no symptoms. Epidemiology Most commonly affects patients over 45 and has a strong male predilection (M:F = 5:1). M...
Article

Mediastinal lymph node enlargement

Mediastinal lymph node enlargement can occur from a wide range of pathologies, either by its own or in association with other lung pathology. Historically, a size cut-off of 10 mm short-axis diameter was used.  Terminology Although mediastinal lymphadenopathy is used interchangeably - by some ...
Article

Medullary thyroid cancer (staging)

Medullary thyroid cancer staging refers to TNM staging of medullary thyroid carcinomas. Papillary, follicular, and anaplastic thyroid carcinomas have similar TNM category definitions but different prognostic stage group definitions. The following article reflects the 8th edition manual published...
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Medulloblastoma

Medulloblastomas are the most common malignant brain tumor of childhood. They most commonly present as midline masses in the roof of the 4th ventricle with associated mass effect and hydrocephalus. Treatment typically consists of surgical resection, radiation therapy, and chemotherapy, with the ...
Article

Meningeal hemangiopericytoma

Meningeal hemangiopericytomas are rare tumors of the meninges, now considered to be aggressive versions of solitary fibrous tumors of the dura, often presenting as a large and locally aggressive dural mass, frequently extending through the skull vault. They are difficult to distinguish on imagin...
Article

Meningeal melanocytoma

Meningeal melanocytomas are rare benign primary melanocytic tumors of the CNS that are derived from leptomeningeal melanocytes. They can occur anywhere along the neuraxis but are most commonly found in the spinal canal near the foramen magnum, as well as the posterior cranial fossa, Meckel cave,...
Article

Meningeal melanomatosis

Meningeal melanomatosis is an aggressive version of meningeal melanocytosis and one of the recognized primary melanocytic tumors of the CNS. It represents proliferation of melanocytic cells within the subarachnoid space 1. There is a strong association with cutaneous melanocytic lesions, in whic...
Article

Meningioma

Meningiomas are extra-axial tumors and represent the most common tumor of the meninges. They are a non-glial neoplasm that originates from the meningocytes or arachnoid cap cells of the meninges and are located anywhere that meninges are found, and in some places where only rest cells are presum...
Article

Mesorectal lymph nodes

Mesorectal lymph nodes refers to lymph nodes that are present in the mesorectal fascia. Their assessment is important in the staging of colorectal tumors such as rectal cancer and anal cancer.  Distribution  According to one study, the majority of nodes were located in the proximal two-thirds ...
Article

Mesothelioma

Mesothelioma, also known as malignant mesothelioma, is an aggressive malignant tumor of the mesothelium. Most tumors arise from the pleura, and so this article will focus on pleural mesothelioma. Given the presence of the mesothelium in different parts of the body, mesothelioma can arise in var...
Article

Mesothelioma (summary)

This is a basic article for medical students and other non-radiologists. Pleural mesotheliomas are malignant tumors of the lining of the lungs. There is a strong association with asbestos exposure. Reference article This is a summary article; read more in our article on mesothelioma. Summary...
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Metachronous breast cancer

Metachronous breast cancers are two breast cancers that occur in either breast in two different time periods. Treatment and prognosis The survival rate of women with metachronous breast cancers diagnosed within two years of the original primary is worse than those with unilateral disease 4.
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Metachronous (pathology)

The term metachronous is used in oncology to refer to two (or more) independent primary malignancies, when the second (or third, etc.) malignancy arose more than six months after the diagnosis of the first malignancy 1,2. These may be in the same, or in different, organs. See also synchronous ...
Article

Metastases to testis

Metastases to testis are a very rare cause of a testicular mass and may be bilateral in up to 15% of patients.  Epidemiology Metastases to the testes are apparent in ~0.04% of autopsy studies in patients with known malignancy. The average age is 57 years, much older than the primary age for pr...
Article

Metastases to the breast

Metastases to the breast from non-mammary primary tumors are uncommon and account for 0.5-2.0% of all breast malignancies.  Clinical presentation Metastases do not tend to cause retraction of the skin or nipple. Metastatic lesions are much more likely to be multiple or bilateral than primary c...

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