Cerebral radiation necrosis refers to necrotic degradation of brain tissue following intracranial or regional radiation either delivered for the treatment of intracranial pathology (e.g. astrocytoma, cerebral arteriovenous malformation) or as a result of irradiation of head and neck tumors (e.g....
The differential for peripheral or ring enhancing cerebral lesions includes:
demyelination (incomplete ring)
tumefactive demyelinating lesion (incomplete ring)
Convenient mnemonics for the causes of cerebral ring enhancing lesions are:
MAGIC DR or DR MAGIC
DR MAGIC L
MAGIC DR or DR MAGIC
I: infarct (subacute phase), inflammatory - neurocysticercosis (NCC), tuberculoma
Cervical lymph node staging refers to evaluating regional nodal metastasis from primary cancer of the head and neck. The following article reflects the 8th edition of the TNM staging system published by the American Joint Committee on Cancer, which is used for staging starting January 1, 2018 1,...
Chemotherapy induced cholangitis is caused when intra-arterial chemotherapy is introduced to treat liver metastases. This causes strictures of the common hepatic duct and main ducts, but spares distal and proximal (i.e. common bile duct and intrahepatic ducts).
Unfortunately the pediatric population is susceptible to malignancies. The most common entities, in overall order of frequency, are 1-4:
leukemia/lymphoma: ~35% *
acute lymphoblastic leukemia: 23%
Hodgkin disease: 5%
acute myelogenous leukemia: 4%
central nervous system malignancies: ~20%
Use only the size of the tumor during evaluation of response to chemotherapy has some pitfalls and limitations, especially when the estimated response for specific tumors such as gastrointestinal stromal tumor (GIST).
The Choi response criteria for GIST proposed that tumor attenuation could pro...
Cholangiohepatoma refers to a synchronous cholangiocarcinoma and hepatocellular carcinoma. It is a rare and aggressive primary hepatic tumor. The origin of cholangiohepatoma is closely linked to the origin of cholangiocarcinoma rather than hepatocellular carcinoma (HCC).
Choledochal cysts represent congenital cystic dilatations of the biliary tree. Diagnosis relies on the exclusion of other conditions (e.g. tumor, gallstone, inflammation) as a cause of biliary duct dilatation.
Choledochal cysts are rare, with an incidence of 1:100,000-150,000. Alt...
Choriocarcinoma is an aggressive, highly vascular tumor. When it is associated with gestation, it is often considered part of the spectrum of gestational trophoblastic disease; it is then termed gestational choriocarcinoma. When it occurs in the absence of preceding gestation, it is termed non-g...
Choroid plexus malignancies can be classified as primary or secondary neoplasms of the choroid plexus:
choroid plexus papilloma (CPP)
WHO Grade I, and WHO Grade II when atypical
choroid plexus carcinoma (CPC)
WHO Grade III
Chronic myelomonocytic leukemia (CMML) is a relatively rare clonal hematologic disorder. In the World Health Organization classification, it is listed as a disorder with features of both myelodysplastic syndromes and myeloproliferative neoplasms.
Can be variable but many ...
The circumferential resection margin (CRM) is a term used in rectal carcinoma excision surgery (such as total mesorectal excision (TME)).
Pathologic evaluation of the resection margin on the excised rectum has been considered important for determining the risk of local recurrence. A margin of ≤...
Clavicle tumors may be malignant or benign.
osteoma: uncommon, sclerotic, hamartomatous surface lesion
enchondroma: rare, geographic, intramedu...
Clear cell meningiomas are a histological variant of meningioma with poorer prognosis and a higher rate of recurrence. They are therefore considered WHO grade 2 tumors, regardless of mitotic index, cellular atypia/anaplasia, or presence of brain invasion.
Clear cell meningiomas h...
Clear cell renal cell carcinoma is the most common type of renal cell carcinoma.
The average age of onset of sporadic clear cell renal carcinoma is 61 years-old. In cases associated with Von Hippel-Lindau disease the average age of onset is 37 years 1.
Clear cell sarcomas of the kidney (CCSK) are a rare mesenchymal renal tumor that account for ~5% of primary renal neoplasms in the pediatric population 1.
Clear cell sarcoma of the kidney is the second most common primary malignant pediatric renal neoplasm after Wilms tumor, with...
Clear cell tumors of the lung are rare benign pulmonary neoplasms that contain an abundant amount of glycogen. It is often classified under the spectrum of perivascular epithelioid cell tumors (PEComas).
Usually seen as a rounded, smooth-walled, and peripheral parenchymal...
CNS capillary telangiectasiae(s) are small, asymptomatic low flow vascular lesions of the brain.
As these lesions are asymptomatic, diagnosis usually matches the age of first imaging with MRI, and as such are most frequently found in middle-aged and elderly adults. Their inciden...
Coarsened hepatic echotexture is a sonographic descriptor where there uniform smooth hepatic echotexture of the liver is lost. This can occur due to number of reasons which include:
conditions that cause hepatic fibrosis 1
various types of hepatitis 3
Celiac plexus block under image guidance is an easy and safe percutaneous procedure with good outcomes for pain palliation in patients who have chronic abdominal pain related to the celiac ganglia.
This usually includes patients with advanced cancers, especially from upper abdominal viscera, s...
Colon polyps are mucosal outgrowths of the colon wall. They are of interest to physicians and radiologists because of the accepted progression of adenomatous polyps to colon carcinoma.
adenomatous colon polyps
villous colon polyps
This is a basic article for medical students and other non-radiologists
Colorectal cancer, also called colorectal carcinoma (CRC), is the most common cancer of the gastrointestinal tract and the second most frequently diagnosed malignancy in adults. CT and MRI are the modalities most frequently...
Colorectal carcinoma (CRC) is the most common cancer of the gastrointestinal tract and the second most frequently diagnosed malignancy in adults. CT and MRI are the modalities most frequently used for staging. Surgical resection may be curative although five-year survival rate is 40-50%.
Computed tomography texture analysis (or CTTA) is a method to obtain new useful biomarkers that provide objective and quantitative assessment of tumor heterogeneity by analyzing the differences and patterns within the pixel values of an image. CTs can be worked with as a matrix of numbers, corre...
With the advent of echocardiography, and cardiac CT and MRI, the role of chest x-rays in evaluating congenital heart disease has been largely been relegated to one of historical and academic interest, although they continue to crop up in radiology exams. In most instances a definite diagnosis ca...
A congenital neuroblastoma is defined as neuroblastoma identified within a month of birth, and is divided into :
In most cases they present as stage 1, 2 or 4S (see neuroblastoma staging).
In 90% of cases fetal neuroblastomas ar...
A handy mnemonic to recall cortically-based brain tumors is:
P: pleomorphic xanthoastrocytoma
D: dysembryoplastic neuroepithelial tumor (DNET); desmoplastic infantile astrocytoma and ganglioglioma
The CT angiogram sign refers to vessels appearing prominent during a contrast enhanced CT as they traverse an airless low attenuation portion of consolidated lung. Although initially thought to be specific for bronchoalveolar carcinoma, it has now been recognised as a generic appearance provided...
CT guided thoracic biopsy is usually performed for the diagnosis of suspicious lung, pleural or mediastinal lesions. It can be performed as an outpatient where patient monitoring and complications support are available. A small percentage of lung and pleural biopsies may be performed under ultr...
The curtain sign, also known as the draped curtain sign, in neuroimaging refers to the appearance of a vertebral body mass that extends posteriorly towards the anterior epidural space.
The posterior longitudinal ligament is strongly attached to the posterior vertebral body cortex in the midline...
Cutaneous and subcutaneous metastases are not uncommon, occurring in ~5% (range 0.7-10.4%) of internal malignancies, and representing 2% of skin cancers. The Sister Mary Joseph nodule is a well known cutaneous metastasis.
These metastases can come from haematogenous or lymphatic spre...
Cystic adrenal neoplasms are uncommon and only account for a minority of cystic adrenal lesions 3. They may be represented several histological types:
adrenal adenoma 1
adrenal cortical carcinoma 1,2
adrenal epithelioid angiosarcoma 2
teratoma (pediatric population) 4
Cystic glioblastoma is a descriptive term for one form of glioblastoma that contains a large cystic component, rather than being a pathological subtype.
Please refer to the main article on glioblastoma for a broad discussion on this tumor.
The main challenge in discrim...
The differential for cystic lesions of the pancreas includes:
intraductal papillary mucinous neoplasm (IPMN)
serous cystadenoma uncommonly uni/macrolocular
simple pancreatic cyst
pancreatic cysts occur in association with
von Hippel Lindau syndrome
The term cystic meningioma is applied to both meningiomas with intratumoral degenerative cyst formation as well as those with peritumoral arachnoid cysts or reactive intraparenchymal cysts.
They should not be confused with microcystic meningiomas, a distinct variant, in which the cysts are mic...
Cystic or necrotic appearing lymph nodes can be caused by a number of infectious, inflammatory or malignant conditions:
squamous cell carcinoma metastases
plasmacytoid T-cell leukemia
acute myeloid leukemia
herpes simplex lymphadenit...
Cystic nephromas, previously known as multilocular cystic nephromas, are rare benign renal neoplasms classically occurring in adult females in the 4th and 5th decades. As of the 2016 WHO classification, they are considered distinct from pediatric cystic nephromas which have associated DICER1 gen...
Cystic pulmonary metastases are atypical morphological form on pulmonary metastases where lesions manifest as distinct cystic lesions. It is slightly different form the term cavitating pulmonary metastases in that the lesions are extremely thin walled.
It has been reported with many ...
The Deauville five-point scale (Deauville 5ps) is an internationally-recommended scale for routine clinical reporting and clinical trials using FDG-PET/CT in the initial staging and assessment of treatment response in Hodgkin lymphoma (HL) and certain types of non-Hodgkin lymphomas (NHL).
The deep inguinal nodes are located within the femoral sheath, medial to the femoral vein. They receive afferent lymphatic drainage from the deep lymphatics of the distal lower extremity and perineum (e.g. glans penis / clitoris), and drain proximally into external iliac lymph nodes via channels...
The dense hilum sign suggests a pathological process at the hilum or in the lung anterior or posterior to the hilum. Malignancy, especially lung cancer, should be suspected.
On a well-centred chest posteroanterior (PA) radiograph the density of the hilum is comparable on ...
A Denver shunt, or peritoneovenous shunt, is a device used to shunt ascites to the superior vena cava in patients with refractory ascites.
The proximal end is located in the peritoneal cavity and the distal end in the superior vena cava, with a subcutaneous course in the anterior chest wall. It...
Dermatofibrosarcoma protuberans (DFSP) is a low-grade malignant tumor arising from dermal and subcutaneous tissues, and is the most common cutaneous sarcoma (although overall still quite rare). It is most commonly found at the trunk and proximal extremities 6.
Its behavior is notable for a high...
Dermatomyositis is an autoimmune inflammatory myositis.
There is a recognised female predilection. It has a bimodal age of presentation depending on the variant:
juvenile dermatomyositis (JDM): affects children and tends to be more severe
adult dermatomyositis (ADM): typically a...
Desmoid tumors are benign, non-inflammatory fibroblastic tumors (see WHO 2002 classification of soft tissue tumors) with a tendency for local invasion and recurrence but without metastasis.
The terms desmoid tumor and aggressive fibromatosis are occasionally used synonymously by so...
Desmoplastic fibromas are extremely rare bone tumors that do not metastasise but may be locally aggressive. They are considered to be a bony counterpart of soft tissue desmoid tumors and are histologically identical.
Incidence is ~0.3%. The most common areas of involveme...
Desmoplastic small round cell tumors are a rare and highly aggressive primary peritoneal malignancy.
They are usually seen in young adolescents and has male predominance with a mean survival of 2-3 years.
It usually presents with a palpable abdominal mass a...
Diabetic mastopathy is a condition characterized by the presence of a benign tumor like breast masses in women with long-standing type 1 or type 2 insulin-dependent diabetes. The condition has also been reported in men. A similar condition is lymphocytic mastitis but this occurs in non-diabetics...
A gas filled focal collection in the right upper upper quadrant on plain film can occur from a number of pathologies. Things to consider are
entero biliary fistula : common types include cholecysto-duodenal fistula and cholecysto-colic fistula and. Can occur with
gallstone ileus (majority of ...
An anterosuperior mediastinal mass can be caused by neoplastic and non-neoplastic pathology. As their name suggests, they are confined to the anterior mediastinum, that portion of the mediastinum anterior to the pericardium and below the level of the clavicles.
The differential diagnosis for a...
Diffuse astrocytomas, also referred to as low-grade infiltrative astrocytomas, are designated as WHO II tumors of the brain. The term diffuse infiltrating means there is no identifiable border between the tumor and normal brain tissue, even though the borders may appear well-marginated on imagin...
Useful mnemonics for remembering causes of diffuse bony sclerosis include:
3 M's PROOF
Regular Sex Makes Occasional Perversions Much More Pleasurable And Fantastic 1
3 M's PROOF
metastases (osteoblastic metastases)
Diffuse brainstem gliomas, also known as diffuse intrinsic brainstem glioma (DIBG), is a term used to describe infiltrating astrocytomas, no longer recognised as a distinct entity in the 2016 update to the WHO classification of CNS tumors. It encompassed a variety of tumors, ranging from WHO gra...
A diffuse homogeneous bone marrow FDG uptake usually reflects hyperplastic bone marrow which can be seen in the following conditions:
granulocyte colony stimulating factor (G-CSF)
Distal appendicular skeletal metastases, especially distal to the knee and elbow joints, are uncommon.
Localised pain and swelling, along with pathological fractures, are the most common 3.
Malignancies that most commonly spread to appendicular skel...
Drash syndrome, also known as the Denys-Drash syndrome, is associated with an abnormal WT1 gene (Wilms tumor gene) and consists of:
A ductal adenoma of the breast is a benign glandular tumor of the breast that usually fills and distends the ductal lumen.
They may occur in women of all ages, although the majority of patients are 60 years of age or greater 3.
Ductal adenomas usually prese...
Duodenal filling defects may be caused by a wide variety of duodenal pathology which may be divided by their location and pathological process.
common bile duct impression
Note: please refer to duodenal mucosal nodular fill...
Dural or pachymeningeal metastases are a relatively common cause of dural masses, although they are less common than brain metastases and meningiomas. They can occur both within the spine and intracranially - this article is focused on intracranial dural masses.
A useful mnemonic to remember differential diagnoses associated with a dural tail sign is:
My Scary Dog Likes To Stand Guard
D: dural metastases
Dysembryoplastic neuroepithelial tumors (DNET) are benign (WHO Grade I) slow growing glioneuronal tumors arising from either cortical or deep grey matter. The vast majority are centred in cortical grey matter, arise from secondary germinal layers, and are frequently associated with cortical dysp...
Dysplastic liver nodules are focal nodular regions (≥1 mm) without definite evidence of malignancy.
They have been found in cirrhotic patients with a prevalence of 14% (size >1.0 cm) to 37% (size >0.5 cm) 2.
Epstein-Barr virus-associated smooth muscle tumors (EBV-SMT) are rare and encountered in immunocompromised individuals.
These tumors are generally exceedingly rare, and only seen with any frequency in the setting of immunosuppression, particularly in HIV/AIDS patients, but also po...
The Eastern Cooperative Oncology Group (ECOG) is one of the largest clinical cancer research organizations in the United States and conducts clinical trials in all types of adult cancers.
The ECOG performance status is a scale used to assess how a patient's disease is progressing, assess how th...
Elevated vitamin B12 (also known as hypervitaminosis B12 or hypercobalaminaemia) is most important as a diagnostic and prognostic marker for malignant disease 1,3. Very high serum levels of vitamin B12 do not seem to have any observable deleterious effects 2.
Primary neoplasms which may result in endobronchial metastases may be memorized by utilizing the following mnemonic:
Kiss My RBC 1
K: Kaposi sarcoma
R: renal cell carcinoma
B: breast cancer
C: colorectal carcinoma, cervical carcinoma, carcinoid
Endometrial carcinoma is generally considered the most common gynecological malignancy 1,5. It frequently presents with vaginal bleeding. Both ultrasound and pelvic MRI are useful modalities for evaluation.
Endometrial carcinoma is the most common gynecological malignancy, with pe...
Endometrial hyperplasia is abnormal proliferation of the endometrial glands and stroma, defined as diffuse smooth thickening >10 mm 13. One of the main concerns is the potential malignant transformation of the endometrial hyperplasia to endometrial carcinoma.
Endosteal scalloping refers to the focal resorption of the inner layer of the cortex (i.e. the endosteum) of bones, most typically long bones, due to slow-growing medullary lesions.
It is important to note that although it is evidence of a slow non-infiltrative lesion, it does not equate to ben...
Engraftment syndrome (ES) refers to a potential early complication of haematopoetic stem cell transplantation. It is thought to be related to increased capillary permeability and comprises of a combination of symptoms and signs which include
erythrodermatous skin rash
Eosinophils, also less commonly known as acidophiles, are myeloid granulocytes and form one of the main types of white blood cells. Their counts are routinely measured as part of a full blood count. They have important roles in fighting parasitic infections, but are increasingly recognised as ha...
Ependymomas represent a relatively broad group of glial tumors most often arising from the lining the ventricles of the brain or the central canal of the spinal cord. They account for ~5% of all neuroepithelial neoplasms, ~10% of all pediatric brain tumors and up to 33% of brain tumors occurring...
Ewing sarcomas are the second most common malignant primary bone tumors of childhood after osteosarcoma, typically arising from medullary cavity with invasion of the Haversian system. They usually present as moth-eaten destructive permeative lucent lesions in the shaft of long bones with large s...
Exophytic is a descriptive term used by radiologists/pathologists to describe solid organ lesions arising from the outer surface of the organ of origin.
Literally exophytic only refers to those lesions arising from the outer surface, however radiologists and pathologists use the term to include...
Extramedullary hematopoiesis is a response to the failure of erythropoiesis in the bone marrow.
This article aims to a general approach on the condition, for a dedicated discussion for a particularly involved organ, please refer to the specific articles on:
extramedullary hematopoiesis in the...
Extramedullary hematopoiesis in the spleen represents a physiologic compensatory event that may be seen in many haematologic diseases leading to chronic anemia. The liver and the spleen are the most common site of extramedullary hematopoiesis, both usually manifesting on imaging as organomegaly ...
Facial nerve schwannoma (FNS), also known as facial nerve neuroma/neurilemoma, is a schwannoma that arises from the facial nerve. They are generally uncommon, and when involving the temporal bone, make up less than 1% of all temporal bone tumors.
FNS is a rare tumor 2.
Familial adenomatous polyposis syndrome (FAPS) is characterized by the presence of hundreds of adenomatous polyps in the colon. It is the most common of the polyposis syndromes.
Familial polyposis coli, attenuated familial adenomatous polyposis and Gardner syndrome are all variants...
Fascicular sign is a finding on T2-weighted MRI images that suggests a lesion of neurogenic origin. It is characterized by multiple small ring-like structures with peripheral hyperintensity representing the fascicular bundles within the nerves.
It is found in various neurogenic tumors, includin...
Fetal cardiac tumors refer to primary cardiac tumors that can present in the in utero population.
Fetal cardiac tumors are rare; the prevalence, reported from autopsy studies of patients of all ages, varies from 0.0017-0.28 % 2.
Known cardiac tumor types that present ...
Fibrinous pericarditis results from fine granular roughening of the pericardium.
Pericardial friction rub may be heard.
acute rheumatic fever
myocardial infarction: Dressler syndrome
chronic renal fail...
Fibrolamellar hepatocellular carcinoma is a distinct histological variant of hepatocellular carcinoma characterized on microscopy by laminated fibrous layers between the tumor cells. It is important as it has different demographics and risk factors compared to 'standard' hepatocellular carcinoma...
Fibrosarcoma of the breast is a type of malignant stromal sarcoma that rarely occurs as a primary tumor within the breast.
A fibrosarcoma is composed of immature mesenchymal elements surrounded by a collagenous substance. It is a type of breast sarcoma with a predominant “herringbon...
The FIGO staging systems are determined by the International Federation of Gynecology and Obstetrics (Fédération Internationale de Gynécologie et d’Obstétrique).
In general, there are five stages:
stage 0: carcinoma in situ (common in cervical, vaginal, and vulval cancer)
stage I: confined to...
Finger clubbing, also called "drumstick fingers", is a common clinical sign in patients with heart or lung disease. The term is used to describe an enlargement of the distal phalanges of the fingers, giving them a drumstick or club-like appearance.
Finger clubbing presen...
Flare phenomenon or osteoblastic flare phenomenon refers to interval visualization of lesions with a sclerotic rim around an initially lytic lesion or sclerosis of lesions previously undetected on radiograph or CT in the setting of follow-up of an oncological patient with other signs of partial ...
Fluid-fluid levels in bone tumors is a commonly encountered finding, both in benign as well as malignant bone tumors, and can be used to differentiate between the two.
Method of assessment
On the sagittal T2W image:
measure the length of the largest fluid-fluid level (A)
measure the maximum ...
Fluorine-18-labeled sodium fluoride (also known as 18F-NaF or sodium fluoride) is a PET radiotracer used primarily for skeletal imaging.
Fluorine-18-labeled sodium fluoride is an ionic compound comprised of a single sodium atom bound to a positron-emitting isotope of fluorine.
A popular mnemonic to help remember causes of focal sclerotic bony lesions is:
H: healed non-ossifying fibroma (NOF)
E: Ewing sarcoma
I: infection or infarct
F: fibrous dysplasia
Follicular lymphoma is the most common subtype of non-Hodgkin lymphoma (NHL)
Estimated to account for ~45% of all NHL cases 1. Higher rates in North America and Europe 4.
Nodal effacement by closely packed follicles containing small cleaved cells without nucleoli (cen...
Follicular thyroid carcinoma (FTC) is the second most frequent malignancy of the thyroid gland after papillary cancer and accounts for ≈10-20% of all thyroid neoplasms.
It typically occurs in women and in an older age group than papillary (i.e. 40-60 years of age).
Fukuoka consensus guidelines, also referred to as the Tanaka criteria, is a classification system for intraductal papillary mucinous neoplasms (IPMNs) and mucinous cystic neoplasms (MCNs).
The prior international consensus guidelines (2006) were referred to as the Sendai criteria, which later ...