The 2014 WHO classification is one of the classification systems for endometrial stromal tumors (EST).
Endometrial stromal tumors constitute <2% of all uterine tumors and <10% of uterine mesenchymal neoplasms 1.
Over the past four decades, EST classification has gone through various modificat...
3D conformal radiation therapy (3D-CRT) is a radiation therapy technique that involves CT planning where the volume to be treated is defined on a 3D data set. Therefore, organs at risk can also be delineated to shield these and reduce treatment side effects. Radiotherapy planning software is use...
The CT abdomen-pelvis protocol serves as an outline for an examination of the whole abdomen including the pelvis. It is one of the most common CT protocols for any clinical questions related to the abdomen and/or in routine and emergencies. It forms also an integral part of trauma and oncologic ...
A mnemonic for causes of abdominal distension (6 Fs) is:
F: fulminant mass
Acinic cell carcinoma of the lung (also known as a Fechner tumor) is a type of lung carcinoma of the salivary gland type. It is extremely rare, especially when it presents in the form of primary acinic cell carcinoma.
Histologically, they are comprised of clear cells with abundant gr...
An acquired tracheo-esophageal fistula refers to a pathological communication between the trachea and esophagus due to a secondary cause.
Acquired causes of tracheo-esophageal fistulae can be divided into those that are related to malignancy (common) and those from other causes (unco...
Active surveillance describes a management option aiming at close monitoring of a specific stage in disease and minimizing adverse treatment-related effects without compromising survival at the same time. Curative or definite treatment is intended and offered upon deterioration or explicit patie...
Acute abdominal pain is a common acute presentation in clinical practice. It encompasses a very broad range of possible etiologies and diagnoses, and imaging is routinely employed as the primary investigative tool in its modern management.
A subgroup of patients with acute abdomina...
Acute airspace opacification with lymphadenopathy is a subset of the differential diagnosis for generalized airspace opacification and includes:
post-obstructive causes (usually chronic, but 'new' changes can occur)
primary lung cancer
Acute lymphoblastic leukemia (ALL) is a malignant disorder of the bone marrow characterized by the proliferation of the lymphoid progenitor cells.
Acute lymphoblastic leukemia is the commonest form of childhood leukemia, accounting for ~80% of pediatric leukemia cases 1. In adults...
Acute myeloid leukemia (AML), also referred to as acute myelogenous leukemia, is a hematological malignancy characterized by the abnormal clonal proliferation of immature myeloid precursors (myeloblasts) or poorly differentiated cells of the hematopoietic system. It primary infiltrates the bone ...
Adenocarcinoma in situ, minimally invasive adenocarcinoma and invasive adenocarcinoma of the lung are relatively new classification entities which replace the now-defunct term bronchoalveolar carcinoma (BAC).
In 2011 the International Association for the Study of Lung Cancer (IASLC) and several...
Adenocarcinomas in situ (AIS) of the lung refer to a relatively new entity with falls under the spectrum of pre-invasive lesions of the lungs. This entity partly replaces the noninvasive end of the previous term bronchoalveolar carcinoma. Adenocarcinoma in situ is defined as a localized adenocar...
Adenocarcinoma of the lacrimal glands is rare, with few cases reported in the literature since it was first described in 1996 1. Primary adenocarcinoma of the lacrimal gland is extremely rare; only 9 cases have been reported in the literature 1,2. It can be classified into high- and low-grade ma...
Adenocarcinoma of the lung is the most common histologic type of lung cancer. Grouped under the non-small cell carcinomas of the lung, it is a malignant tumor with glandular differentiation or mucin production expressing in different patterns and degrees of differentiation.
This article brings...
Adenocarcinoma of the prostate with neuroendocrine differentiation is a malignant neuroendocrine tumor of the prostate which only differs from acinar or ductal adenocarcinoma on immunohistochemistry staining.
Adenocarcinoma of the prostate with neuroendocrine differentiation is an ac...
Adenocarcinomas of the seminal vesicles are the most common malignant primary neoplasm of the seminal vesicles.
Primary adenocarcinoma of the seminal vesicles are very rare 1,2 and can be observed at a wide age range 2.
There is a lack of specific symptoms ...
Adenocarcinoma of the urinary bladder is rare and accounts for only ~1% of all bladder cancers (90% are transitional cell carcinomas).
Metaplasia of urinary bladder induced by chronic irritation or infection can lead to adenocarcinoma. Pathological types of adenocarcinoma of the urin...
Adenoid cystic carcinomas are a rare histological subtype of adenocarcinoma.
Adenoid cystic carcinomas are generally considered low grade 4. The tumors have a notable tendency for perineural spread.
They have a wide distribution and mainly occur in relation to the airways,...
Adenoid cystic carcinoma (ACC) of the breast is a rare subtype of breast cancer.
They account for only 0.1-0.4% of all breast cancers.
The tumor demonstrates a strikingly characteristic microscopic pattern similar to that of adenoid cystic carcinoma of the salivary gla...
Adenoid cystic carcinoma (ACC) of the lung is a type of non-small cell lung cancer.
They are classified under lung carcinomas of the salivary gland type. Primary occurrence in the lung parenchyma is rare, while in the thorax they occur more commonly as adenoid cystic carcinoma of the...
Adenoid cystic carcinoma of the salivary glands is the second most common malignancy involving the minor salivary glands behind mucoepidermoid carcinoma and the second most common malignancy involving the parotid gland.
Adenoid cystic carcinomas arise more commonly in the minor saliv...
Adenoid cystic carcinomas of the tracheobronchial tree are a type of low-grade tracheal tumor. They are considered to be the second most common primary tumor of the trachea.
They are usually first recognized in patients in their 4th and 5th decades. There is no recognized gender p...
Adenomatoid odontogenic tumors are rare and differ from most other dentition related lesions in that they more frequently occur in the maxilla.
They are also seen more frequently in females, most frequently in the second decade of life.
They present as an e...
Adenosquamous cell carcinoma (ASC) of the cervix is a rare histological subtype of cervical carcinoma.
It has components of both cervical adenocarcinoma and cervical squamous cell carcinoma.
An adenosquamous histology appears to be an independent predictor of poor outcome...
Adenosquamous carcinoma of the lung is a rare type of non-small cell lung cancer containing both components of lung adenocarcinoma and lung squamous cell carcinoma (SCC).
It is thought to constituting 0.4-4% of cases non-small cell lung cancer.
cigarette smoking 8
Adrenal calcification is not a rare finding in healthy asymptomatic people and is usually the result of previous hemorrhage or tuberculosis. Addison disease patients only occasionally develop calcification.
sepsis: Waterhouse-Friderichsen syndrome
An adrenal collision tumor or collision tumor of the adrenal gland is an uncommon condition where two histologically distinct tumors abut each other or are in close proximity in the same adrenal gland.
Collision tumors have been reported in nearly every organ, for example, collision ...
Primary adrenal cortical carcinoma (also known as adrenocortical carcinoma) is a highly malignant but rare neoplasm. It may present as a hormonally active or an inactive tumor.
Although men and women are affected equally, functioning tumors are more common in females, who are als...
Adrenal lymphoma can refer to:
primary adrenal lymphoma: rare
can be bilateral in around 70% of cases 1
secondary involvement of the adrenal glands with lymphoma: more common
The presentation can be variable and may include adrenal insufficiency, worsening general sta...
Adrenal metastases are the most common malignant lesions involving the adrenal gland. Metastases are usually bilateral but may also be unilateral. Unilateral involvement is more prevalent on the left side (ratio of 1.5:1).
They are present at autopsy in up to 27% of patients with ...
Cervical lymphadenopathy in an adult can result from a vast number of conditions. They include:
from head and neck tumors
other neoplastic lesions
Adult fibrosarcomas are rare, malignant and highly aggressive fibroblastic soft tissue tumors. They constitute a diagnosis of exclusion.
Adult fibrosarcomas by more recent definition are rare and make up for around 1% of soft tissue sarcomas. They are mostly seen in middle-aged pe...
Aerogenous metastases are a rare form of metastases that can occur in the lung due to aerogenous spread along the airways.
Aerogenous metastases are usually from primary lung cancer disseminating along the airways from a different part of the lung and less commonly from other parts o...
Aflatoxins are naturally-occurring mycotoxins that are produced by Aspergillus species, especially Aspergillus flavus. They are acutely toxic and carcinogenic.
High-level aflatoxin exposure can result in acute aflatoxicosis with acute hepatic necrosis, leading to cirrhosis, and ...
Aggressive fibromatosis is a type of musculoskeletal fibromatosis. While it is a non-metastasizing fibrous lesion, it is thought to be a true neoplasm that arises from the fascial and musculoaponeurotic coverings, sometimes at the site of a traumatic or post-surgical scar.
Alcian blue stain is a histological stain utilized for the identification of extracellular matrix proteoglycans, like glycosaminoglycans and hyaluronic acid 1, commonly in connective tissue and epithelial malignant neoplasms 2, and also Barrett esophagus, where it can highlight mucosal intestina...
Alveolar soft part sarcoma (ASPS) is a rare, highly vascular, deep soft tissue mesenchymal malignancy that is classically seen in the lower extremities of young adults. They account for <1% of all soft tissue sarcomas.
There is a slight female predilection in patients less than 30...
Ameloblastic carcinomas or malignant ameloblastoma are malignant epithelial odontogenic neoplasms with histologic features ameloblastoma.
Ameloblastic carcinomas are rare tumors approximately accounting for 1% of jaw tumors 1,2. They have been found in a wide age range and are mor...
Ameloblastomas are locally aggressive benign tumors that arise from the mandible, or, less commonly, from the maxilla. Usually present as a slowly but continuously growing hard painless lesion near the angle of the mandible in the 3rd to 5th decades of life, which can be severely disfiguring if ...
Anal cancer is relatively uncommon, accounting for less than 2% of large bowel malignancies. Most cases are squamous cell carcinoma on histology.
It accounts for less than 2% of large bowel malignancies and 1-6% of anorectal tumors (~1.5% of all gastrointestinal tract malignancies...
Anaplastic lymphoma kinase (ALK) fusion oncogene positive non small cell lung cancer refers to a specific set of non small cell lung cancers that contain an inversion in chromosome 2. They are associated with specific clinical features, including never or light smoking history, younger age, and ...
Anaplastic lymphoma kinase (ALK) gene rearrangements are known to occur in association with several tumors. The genes code for an enzyme called anaplastic lymphoma kinase (ALK) or ALK tyrosine kinase receptor (also known as CD246) which is thought to play a role in brain development and exerts i...
Anaplastic thyroid cancer staging refers to TNM staging of anaplastic thyroid carcinomas. Papillary, follicular, and medullary thyroid carcinomas are staged separately. The following article reflects the 8th edition manual published by the American Joint Committee on Cancer, which is used for st...
The anatomy curriculum is one of our curriculum articles and aims to be a collection of articles that represent the core anatomy knowledge for radiologists and imaging specialists.
Head and neck anatomy
Abdominal and pelvic anatomy
Androgen deprivation therapy (ADT), also called androgen suppression therapy or is a form of treatment in prostate cancer, which basically aims to slow prostate cancer growth by blocking the effect of androgens e.g. testosterone.
Such therapy is mainly used for treating men with intermediate- a...
Angiofibromas of soft tissue are benign fibroblastic soft tissue neoplasms permeated by a vascular network that might be found in the periarticular and articular areas of the lower extremities that have been included as a separate entity into the WHO classification of soft tissue tumors in 2020....
Angioimmunoblastic T-cell lymphoma (AITL) (previously known as angioimmunoblastic lymphadenopathy with dysproteinemia (AILD)) is a rare, aggressive (fast-growing) form of peripheral T-cell lymphoma. It only accounts for around 1-2% of all non-Hodgkin lymphoma. It is one of the more common subtyp...
Angiomatoid fibrous histiocytomas (AFH) or angiomatoid fibrous malignant histiocytomas are neoplasms of intermediate biologic potential and are classified as soft tissue tumors of uncertain differentiation.
Angiomatoid fibrous histiocytomas a rare and account for about 0.3% of all...
Angiosarcoma of bone is a malignant vascular tumor of bone. These are rare and account for less than 1% of malignant bone tumors. The majority of these tumors arising in bone are primary; however, a tiny percentage are either radiation-induced or associated with bone infarction
Breast angiosarcomas are a rare vascular breast malignancy.
As primary tumors of the breast, they account for ~0.04% 2 of all breast cancers and tend to occur in younger women, in their 3rd to 4th decades.
Secondary angiosarcoma, related to prior therapy of breast cancer, has an ...
The Ann Arbor staging system was the landmark lymphoma staging classification system for both Hodgkin lymphoma and non-Hodgkin lymphoma. It is named after the town of Ann Arbor in the US state of Michigan where the Committee on Hodgkin's Disease Staging Classification met in 1971 to agree on it....
Germ cell tumors are one of the causes of an anterior mediastinal mass, and any of the germ cell histologies may be identified. They can therefore be divided histologically into:
non-seminomatous germ cell tumors (NSGCT)
yolk sac tumo...
Getting a film with an anterior mediastinal mass in the exam is one of the many exam set-pieces that can be prepared for.
The film goes up and after a couple of seconds pause, you need to start talking:
There is a left sided mediastinal mass that makes obtuse angles with the mediastinal c...
Anterior resection syndrome refers to wide spectrum of symptoms which develop post-sphincter preserving rectal resection for rectal cancer.
Pelvic radiotherapy is a known risk factor to develop anterior resection syndrome.
There have been reports that up to 47% of patients who un...
Apocrine carcinoma of the breast is a rare variant of breast cancer. The diagnosis is mainly pathological as it is difficult to differentiate from other forms of breast cancer on imaging.
It accounts for about 4% of all cases. It is seen most often in females in the age group of 5...
Appendiceal mucoceles occur when there is an abnormal accumulation of mucin causing abnormal distention of the vermiform appendix due to various neoplastic or non-neoplastic causes.
The reported prevalence at appendectomy is 0.2-0.3%. They are thought to typically present in middl...
The apple core sign, also known as the napkin ring sign (bowel), is most frequently associated with constriction of the lumen of the colon by a stenosing annular colorectal carcinoma.
The appearance of the apple-core lesion of the colon also can be caused by other diseas...
Asbestosis refers to later development of diffuse interstitial fibrosis secondary to asbestos fiber inhalation and should not be confused with other asbestos related diseases.
Asbestosis typically occurs 10-15 years following the commencement of exposure to asbestos and is dose re...
The original description of the Askin tumor (by Askin and Rosai in 1979 1), and many studies following it have led to a great deal of confusion. Until recently it has been considered a separate entity or as a type of peripheral primitive neuroectodermal tumor, usually of the chest wall.
Assessment of thyroid lesions is commonly encountered in radiological practice.
hyperplastic/colloid nodule/nodular hyperplasia: 85%
papillary: 60-80% of carcinomas
Asymmetries in mammography represent a spectrum of morphological descriptors for a unilateral fibroglandular-density finding seen on one or more mammographic projections that do not meet criteria for a mass. The term refers to a density finding and should not be confused with asymmetry in breast...
Atypical ductal hyperplasia is a histologically borderline lesion that has some, but not all, of the features of ductal carcinoma in situ. Sometimes the distinction between Atypical ductal hyperplasia and ductal carcinoma in situ are simply defined on the number of ducts involved.
Atypical spindle cell/pleomorphic lipomatous tumors or atypical spindle cell lipoma are benign adipocytic soft tissue neoplasms with a variable proportion of atypical spindle cells, pleomorphic cells adipocytes and other cells with no risk for dedifferentiation but a low risk of local recurrence...
Atypical teratoid/rhabdoid tumors (AT/RT) are an uncommon WHO grade IV tumor, which in the vast majority of cases occurs in young children less than two years of age. It most frequently presents as a posterior fossa mass. AT/RT often resembles medulloblastoma by imaging and even H&E microscopy, ...
Autoimmune lymphoproliferative syndrome (ALPS) is a rare lymphoproliferative condition.
It presents with chronic lymphadenopathy, splenomegaly, and symptomatic multilineage cytopenias in an otherwise healthy child.
It represents a failure of apoptotic mechanis...
BALT lymphoma is an abbreviated term for bronchus-associated lymphoid tissue lymphoma. These neoplasms fall under the broader umbrella of mucosa associated lymphoid tissue (MALT) lymphomas. It is sometimes considered a type of primary pulmonary lymphoma.
Up to half of pat...
Bartholin gland tumors represent neoplasms of the Bartholin glands.
squamous cell carcinoma of the Bartholin gland: tends to be the most common histological subtype
adenocarcinoma of the Bartholin gland
adenoid cystic carcinoma of the Bartholin gland
A basal cell carcinoma (BCC) is one of the commonest non-melanocytic types of skin cancer.
Typically present in elderly fair-skinned patients in the 7th to 8th decades of life. There may be an increased male predilection.
Multiple basal cell carcinomas may be prese...
Basal cell carcinoma of the prostate or prostatic adenoid basal proliferation of uncertain significance is a type of prostate cancer resembling adenoid cystic carcinoma of the salivary glands.
Other terms include 'adenoid cystic carcinoma', 'adenoid basal cell tumor', 'adenoid cyst...
Bat wing or butterfly pulmonary opacities refer to a pattern of bilateral perihilar shadowing. It is classically described on a frontal chest radiograph but can also refer to appearances on chest CT 3,4.
Bat wing pulmonary opacities can be caused by:
pulmonary edema (es...
Benign and malignant characteristics of breast lesions at ultrasound allow the classification as either malignant, intermediate or benign based on work published by Stavros et al. in 1995.
Malignant characteristics (with positive predictive values)
There are a number of benign metastasizing tumors:
benign metastasizing meningioma 1,2
benign metastasizing leiomyoma 3
primary adenoma of thyroid 4
giant cell tumor of bone 5
In most instances predicting benign versus malignant histology of a gallbladder polyp based purely on imaging features is not possible. However, a number of features are helpful in helping to decide the management of a gallbladder polyp.
polyps that are less than 5 mm in...
The Bethesda criteria are an alternative to the Amsterdam criteria for the clinical diagnosis of hereditary non-polyposis colorectal cancer (HNPCC).
Diagnosis of HNPCC is made if any of the following criteria are fulfilled:
Amsterdam criteria are met
2 or more HNPCC related malignancies
Bilateral testicular lesions have a relatively limited differential diagnosis.
lymphoblastic leukemia (acute or chronic)
primary testicular lymphoma is rare but the testes are often the site of lymphoma/leukemia recurrence due to ...
Bing-Neel syndrome is an extremely rare neurological complication of Waldenström macroglobulinemia where there is malignant lymphocyte infiltration into the central nervous system (CNS).
The exact incidence is unknown, however, in one study of patients with Waldenström macroglobul...
Bladder cancer is a broad term used to describe all types of cancers affecting the urinary bladder:
transitional cell carcinoma (urinary bladder): most common primary neoplasm of the bladder
squamous cell carcinoma (urinary bladder): accounts for around 3-8% of all bladder cancers
Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare hematological malignancy. It was previously termed as blastic natural-killer lymphoma or agranular CD4+ natural killer cell leukemia.
It only represent a very small proportion (~0.44%) of all hematological malignancies...
Blow out bone metastases or expansile bone metastases are typically only encountered in a relatively small number of primary malignancies, including 1:
renal cell carcinoma
Occasionally the sclerotic metas...
Body imaging is the term assigned to cross-sectional imaging of the body, which radiologically refers to the chest, abdomen and pelvis. It is often used by radiologists who report this region (sometimes known as body imagers/radiologists) to differentiate their primary area of interest from othe...
There are several bony lesions that can involve or produce a sequestrum.
Brodie abscess: osteomyelitis
certain soft tissue tumors (with bony extension)
malignant fibrous histiocytoma
metastasis (especially from breast ca...
Lymphoma of the bone may represent lymphoma that has originated within that bone itself i.e. primary, or metastasized there from another organ/tissue, i.e. secondary. Secondary forms of bone lymphoma are much more common than the primary bone form.
primary osseous lymphoma
secondary osseous ly...
Normal bone marrow is divided into red and yellow marrow, a distinction made on the grounds of how much fat it contains.
Red marrow is composed of:
reticulum (phagocytes and undifferentiated progenitor cells)
scattered fat cells
a rich v...
Mnemonics to help remember common causes of bony sequestrum include:
E: eosinophilic granuloma
I: infection (Brodie abscess)
L: lymphoma (skeletal)
M: malignant fibrous histiocytoma or metastasis (especially from breast carcinoma)
Borderline ovarian serous cystadenomas lie in the intermediate range in the spectrum of ovarian serous tumors and represent approximately 15% of all serous tumors.
They present at a younger age group 1-2 than the more malignant serous cystadenocarcinomas with a peak age of present...
Brachytherapy, also known as sealed source radiotherapy or endocurietherapy, is a form of radiotherapy where a radioactive source is placed, under the guidance of imaging, within or next to the area requiring treatment. This provides localized targeted internal radiation.
Brachytherapy has bee...
BRAF (B-Raf proto-oncogene serine/threonine-protein kinase) is a proto-oncogene, encoding for a serine/threonine protein kinase. Mutations of BRAF are the most common alteration of the RAS/MAPK pathway and these have been identified in a variety of tumors and congenital syndromes including 1-5: ...
Brain metastases are estimated to account for approximately 25-50% of intracranial tumors in hospitalized patients. Due to great variation in imaging appearances, these metastases present a common diagnostic challenge which can importantly affect the management approach for individual patients.
Common brain tumors in infancy (i.e. under one year of age) are quite different from those of brain tumors in adulthood. Most are located in the supratentorial region (~65%) and they carry a poor prognosis.
The frequency of these tumors varies according to studies, but the most common brain tum...
A breast abscess is a relatively rare but significant complication of mastitis that may occur during breastfeeding, particularly in primiparous women. The clinical context is a key to diagnosis as imaging appearances (particularly ultrasound) can mimic many other entities such as breast carcinom...
Breast architectural distortion is a descriptive term in breast imaging (mammography, ultrasound, and MRI) to indicate that the breast parenchyma is tethered or indented. The finding per se is not a mass.
Architectural distortion is often due to a desmoplastic reaction in which there...
Metastases from breast cancer can be a frequent finding in routine oncoradiological practice.
With the universal use and acceptance of screening mammography, the isolated clinical presentation from metastases from breast carcinoma has become rare in clinical practice. His...