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.

74 results found
Article

Submandibular gland enlargement

Submandibular gland enlargement refers to an increase in the volume of the submandibular gland, exceeding "normal" values of 7.4 ± 1.8 mL 1. Pathology Causes Obstruction sialolithiasis submandibular duct stenosis (e.g. tumor, granulomatous disease) Infection acute sialadenitis: following ...
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Fluid-fluid levels in liver lesions

Fluid-fluid levels in liver lesions are a rare appearance of both benign and malignant conditions. Differential diagnosis benign complicated hepatic cyst 2 hepatic abscess 2 chronic hepatic hematoma 3 biliary cystadenoma 3 hepatic hemangioma (very rare) 2 malignant cystic/necrotic hepat...
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Fat containing brain lesions

Intracranial fat is uncommon and a wide range of differentials should be considered. Neoplastic intracranial dermoid cyst intracranial teratoma intracranial lipoma pericallosal lipoma quadrigeminal cistern lipoma suprasellar cistern lipoma cerebellopontine angle lipoma choroid plexus li...
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Hepatosplenomegaly

Hepatosplenomegaly is simply the simultaneous presence of a pathologically-enlarged liver (hepatomegaly) and spleen (splenomegaly). Pathology Etiology Infection Many infections can produce a mild concurrent enlargement of the liver and spleen. This list is by no means exhaustive. viral EBV...
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Gallbladder cancer

Gallbladder cancer is relatively uncommon compared to other hepatobiliary malignancies. Pathology Primary gallbladder carcinoma gallbladder adenocarcinoma: most common 1 gallbladder squamous cell carcinoma gallbladder neuroendocrine carcinoma gallbladder sarcoma: very rare 2 gallbladder ...
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Patellar tumors

Patellar tumors are extremely rare. They can be either benign or malignant primary bone tumors, or metastases.  Epidemiology Patellar tumors represent just 0.1% of all primary bone tumors 1.  Clinical presentation Patients may present with anterior knee pain and/or a palpable mass 1,3. Path...
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Vulval neoplasms

Vulval neoplasms are rare and mostly seen in elderly female patients. Squamous cell carcinoma (SCC) is the most common malignancy of the vulva and only 30% of them are associated with oncogenic human papillomaviruses (HPVs). Pathology Squamous neoplastic lesions  Premalignant  classic vulvar...
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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

Pure ground glass nodules

Pure ground glass lung nodules (pGGN's) are a subtype of ground glass lung nodules where there is no associated solid component. Pathology Etiology Apart from inflammatory foci they have been shown to represent various pathologies such as 1,3 adenocarcinoma in situ of lung minimally-invasiv...
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Pseudocirrhosis

Pseudocirrhosis is a radiological term used to convey the imaging findings of cirrhosis, but emphasize that it occurs in the setting of hepatic metastases. It is most commonly reported following chemotherapeutic treatment of breast cancer metastases, although has also been reported before treatm...
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Intracranial tumors with calcification

A variety of intracranial tumors exhibit different forms of calcification. Some lesions commonly show calcification while in some tumors, calcification is seen only in few number of cases. In this article these tumors are classified on the basis of frequency of calcification. Commonly calcified...
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Solitary ill-defined osteolytic lesion (differential)

Ill-defined solitary osteolytic lesions can be caused by following entities 1: intraosseous hemangioma chondroblastoma osteoblastoma giant cell tumor fibrosarcoma of bone malignant fibrous histiocytoma chondrosarcoma osteosarcoma Ewing sarcoma angiosarcoma multiple myeloma bone metas...
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Hypervascular metastases

There are several tumors that are noted to cause hypervascular metastases. The list of differential diagnoses includes: renal cell carcinoma (RCC) breast cancer: homogeneously hypervascular liver metastases from the breast are considered rare 3 lung cancer neuroendocrine tumors carcinoid tu...
Article

Apple core sign (colon)

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. Differential diagnosis The appearance of the apple-core lesion of the colon also can be caused by other diseas...
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Cystic pulmonary metastases

Cystic pulmonary metastases are an atypical morphological form of pulmonary metastases where lesions manifest as distinct cystic lesions. It is slightly different from the term cavitating pulmonary metastases in that the lesions are extremely thin walled. Pathology It has been reported with ma...
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Terminal ileitis (differential)

The differential diagnosis for a terminal ileitis is quite extensive, and includes: inflammatory bowel disease Crohn disease (most common) backwash ileitis due to ulcerative colitis infectious colitis Yersinia spp.  Yersinia enterocolitica Yersinia pseudotuberculosis Salmonella spp. ​Sa...
Article

Cardiophrenic angle lesions

The cardiophrenic space is usually filled with fat. However, lesions originating above or lower to the diaphragm can present as cardiophrenic angle lesions. The more common lesions encountered include: pericardial fat pad pericardial cyst pericardial fat necrosis Morgagni's hernia lymphade...
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Pancreatic calcifications

Pancreatic calcifications can arise from many etiologies. Punctate intraductal calcifications chronic pancreatitis alcoholic pancreatitis (20-40%) 2  intraductal, numerous, small, irregular preponderant cause of diffuse pancreatic intraductal calcification gallstone pancreatitis (2%) 2 ​m...
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Solid and enhancing pituitary region mass

Solid pituitary lesions with enhancement are by far the most commonly encountered appearance of pituitary region masses. Differential diagnosis macroadenoma by far the most common entity typically enhances less vividly than other entities elevates the dura of the diaphragma sella (as the or...
Article

Lytic bone metastases

Lytic bone (osteolytic) metastases are distant tumor deposits of a primary tumor within bone characterized by a loss of bone with the destruction of the bone matrix. Epidemiology Lytic bone metastases are more common than sclerotic bone metastases. Diagnosis The diagnosis is usually establis...
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Mixed lytic and sclerotic bone metastases

Mixed lytic and sclerotic bone (osteolytic and osteoblastic) metastases refer to metastatic bone disease with both sclerotic and lytic bone metastases or bone metastases with both components. Diagnosis The diagnosis is established by proof of sclerotic and lytic bone metastases of one primary ...
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Endosteal scalloping

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 1. It is important to note that although it is evidence of a slow non-infiltrative lesion, it does not equate to b...
Article

Well-defined breast cancers (differential)

Certain well-defined breast cancers tend to lack the characteristic spiculation and can give false reassurance of more benign entities on both ultrasound and mammography. These include: certain high grade invasive ductal carcinomas: not enough time for a desmoplastic reaction to form spiculatio...
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Unilateral axillary lymphadenopathy (differential)

Unilateral axillary lymphadenopathy while being more concerning than bilateral axillary lymphadenopathy can still arise from a variety of benign, as well as malignant, causes. Benign mastitis other regional infective causes tuberculosis ipsilateral arm infection, e.g. cellulitis silicone i...
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Asymmetry (mammography)

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...
Article

Fetal cardiac tumors

Fetal cardiac tumors refer to primary cardiac tumors that can present in the in utero population.  Epidemiology Fetal cardiac tumors are rare; the prevalence, reported from autopsy studies of patients of all ages, varies from 0.0017-0.28 % 2. Pathology Known cardiac tumor types that present ...
Article

Spinal metastases

Spinal metastasis is a vague term which can be variably taken to refer to metastatic disease to any of the following: vertebral metastases (94%) may have epidural extension intradural extramedullary metastases (5%) intramedullary metastases (1%) Each of these are discussed separately. Below...
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WHO classification of uterine tumors

The World Health Organization (WHO) classification of tumors of the uterine corpus is a commonly used classification system for uterine tumors. It is part of the 5th edition WHO classification of female genital tumors, published in 2020 1.  Classification Endometrial epithelial tumors and prec...
Article

Diffusely increased bone marrow FDG uptake

A diffuse homogeneous bone marrow FDG uptake usually reflects hyperplastic bone marrow which can be seen in the following conditions: therapy-related granulocyte colony-stimulating factor (G-CSF) post-chemotherapy erythropoietin pathological process myelodysplastic syndromes beta-thalasse...
Article

Generalized osteopenia

Generalized osteopenia refers to osteopenia diffusely affecting the bones. Differential diagnosis The differential diagnosis is wide and includes: osteoporosis: decreased osteoid production osteomalacia: undermineralisation of osteoid hyperparathyroidism multiple myeloma diffuse metastase...
Article

Bulging duodenal papilla

Bulging duodenal papilla​ is a conical or cylindrical protuberance at the medial aspect of the descending or horizontal duodenum at the site of the sphincter of Oddi. It is a finding on small bowel follow-though (and endoscopy) and has a relatively long differential. On cross-sectional imaging, ...
Article

Tumors of the male urethra

Tumors of the male urethra are uncommon. They can be categorized both on the grounds of histology and location. Histology squamous cell carcinoma of the urethra: 80% urothelial/transitional cell carcinoma of the urethra: 15% (predominantly posterior urethra) adenocarcinoma of the urethra: 5%...
Article

Bone lesions with sequestrum

There are several bony lesions that can involve or produce a sequestrum. They include: Common Brodie abscess: osteomyelitis Less common eosinophilic granuloma certain soft tissue tumors (with bony extension)  malignant fibrous histiocytoma lymphoma metastasis (especially from breast ca...
Article

Adult cervical lymphadenopathy (differential)

Cervical lymphadenopathy in an adult can result from a vast number of conditions. They include: malignancy metastases  from head and neck tumors lymphoma other neoplastic lesions Castleman disease Kaposi sarcoma infection bacterial infection viral infection Epstein-Barr virus herpes ...
Article

Ocular pathology

Ocular pathology covers a wide range of conditions and therefore represents the cause of a wide range of symptoms, signs and radiographic features. Ocular metastases account for over 80% of all ocular pathology. With regard to the remainder of ocular lesions, the primary differentiating factor ...
Article

Parotid gland enlargement

Parotid gland enlargement (also known as parotidomegaly) has a wide differential given the significant breadth of pathology that can affect the parotid gland. These can be separated by a standard surgical sieve approach into infective, inflammatory, immune, neoplastic, infiltrative, and congenit...
Article

Clavicle tumors

Clavicle tumors may be malignant or benign. Malignant metastases prostate breast cervix ovary urinary bladder carcinoid osteosarcoma osteosarcoma lymphoma primary metastatic Benign osteoma: uncommon, sclerotic, hamartomatous surface lesion enchondroma: rare, geographic, intramedu...
Article

Focal gas collection in right upper quadrant (differential)

Focal gas collection in right upper quadrant on plain radiographs can occur from a number of pathologies. Things to consider are: enterobiliary fistula: common types include cholecystoduodenal fistula and cholecystocolic fistula. It may occur with: gallstone ileus (being most common) 3 perfor...
Article

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...
Article

Testicular cancer

Testicular cancers are the most common malignancy in men between the ages of 20 and 34 years. Epidemiology Testicular cancer is uncommon, accounting for less than 1% of all internal organ malignancies 2. The commonest histology of the tumor varies with the age of affected individuals. Over 90...
Article

Calcified mediastinal lymph nodes (differential)

There are numerous causes of calcified mediastinal lymph nodes. Common causes include: infectious granulomatous diseases tuberculosis histoplasmosis sarcoidosis silicosis treated lymphoma Uncommon causes include: Pneumocystis jiroveci (PCP) pneumonia metastases thyroid carcinoma: papi...
Article

HIV associated neoplasms

HIV-associated neoplasms are numerous and can be broadly divided into two groups: AIDS-defining malignancies associated but not AIDS defining malignancies AIDS-defining malignancies The development of these malignancies in HIV affected individuals generally implies progression to AIDS 4: Ka...
Article

Solitary sclerotic bone lesion

Solitary sclerotic bone (osteosclerotic or osteoblastic) lesions are lesions of bone characterized by a higher density or attenuation on radiographs or computer tomography compared to the adjacent trabecular bone. However, a specific density range has not been specified for those terms 1. Diffe...
Article

Tumors of muscular origin

There are a number of tumors of muscular origin, which overall are relatively uncommon, representing ~2% of benign soft tissue tumors and ~10% of malignant soft tissue tumors 1.  Pathology The tumors can be divided according to the type of muscle fiber: Skeletal muscle origin benign rhabdom...
Article

Vertebra plana

Vertebra plana (plural: vertebrae planae), also known as the pancake, silver dollar or coin-on-edge vertebra, is the term given when a vertebral body has lost almost its entire height anteriorly and posteriorly, representing a very advanced compression fracture. Pathology It can occur in a var...
Article

Ultrasound appearances of hepatic metastases

Ultrasound appearance of hepatic metastases can have bewildering variation, and the presence of hepatic steatosis can affect the sonographic appearance of liver lesions. Radiographic features Ultrasound Patterns do exist between ultrasound appearance of the hepatic metastases and the likely p...
Article

Cerebral ring enhancing lesions

The differential for peripheral or ring enhancing cerebral lesions includes: cerebral abscess tuberculoma neurocysticercosis metastasis glioblastoma subacute infarct/hemorrhage/contusion demyelination (incomplete ring) tumefactive demyelinating lesion (incomplete ring) radiation necrosi...
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Optic nerve enlargement

Enlargement of the optic nerves is uncommon. Swelling of the optic nerves has a surprisingly broad differential. Etiology neoplastic optic nerve glioma optic nerve meningioma leukemia orbital lymphoma metastases juvenile xanthogranuloma medulloepithelioma involvement by retinoblastoma ...
Article

Sunburst appearance (bone)

Sunburst or sunray appearance describes two separate findings in the bone: a periosteal reaction and a trabeculation pattern. It should not be confused with the sunburst sign of meningioma vascularity.  Sunburst periosteal reaction Sunburst periosteal reaction reflects aggressive periostitis. ...
Article

Splenomegaly

Splenomegaly refers to enlargement of the spleen. The upper limit of the normal adult splenic length is traditionally cited at 12 cm, but lengths upwards of 14 cm can be seen in normal, taller males 7. Terminology Massive splenomegaly is variably defined, including when the spleen is 5 standar...
Article

Adrenal calcification

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.  Pathology Etiology Hemorrhage sepsis: Waterhouse-Friderichsen syndrome blunt abdomi...
Article

Pedunculated intratracheal mass

A pedunculated intratracheal mass has a variety of differential diagnoses: benign tumor, e.g. hamartoma, chondroma, lipoma hemangioma inspissated mucus metastasis to tracheal mucosa, e.g. renal cell carcinoma, melanoma polyp, e.g. inflammatory, antrochoanal papilloma post-intubation trach...
Article

Bilateral testicular lesions

Bilateral testicular lesions have a relatively limited differential diagnosis.  Differential diagnosis Neoplastic  lymphoblastic leukemia (acute or chronic) lymphoma (non-Hodgkin's) primary testicular lymphoma is rare but the testes are often the site of lymphoma/leukemia recurrence due to ...
Article

Unilateral testicular lesions

The differential diagnosis for unilateral testicular lesions is wide-ranging.  Neoplastic Common seminoma (40-50% of testicular malignancies) non-seminomatous germ cell tumors: testicular teratoma testicular epidermoid (teratoma with ectodermal elements only) testicular choriocarcinoma t...
Article

Pelvic masses in females

Pelvic masses in females carry a broad differential diagnosis: benign adnexal cyst leiomyoma pelvic malignancy dermoid endometriosis pelvic inflammatory disease tubo-ovarian abscess hydrosalpinx pregnancy Extragynaecological masses, e.g. colorectal carcinoma, appendicular abscess, lymp...
Article

Intraventricular neoplasms and lesions

Intraventricular neoplasms are rare and arise from periventricular structures such as the walls of the ventricular system, the septum pellucidum and the choroid plexus. Many tumor types arise from or can bulge into the ventricular system, although there are certain lesions that are relatively re...
Article

Hypothalamic lesions

Hypothalamic lesions are numerous representing some entities that are unique to the hypothalamus, as well as many lesions that can be seen elsewhere within the brain. Additionally, due to its proximity to the optic chiasm, third ventricle and pituitary region, many lesions of these locations can...
Article

Tracheal masses

The differential for tracheal masses can be rather wide. For a single mass consider: metastasis  direct invasion from adjacent organ (lung, thyroid, esophagus and larynx) distant metastasis (e.g. melanoma, breast, renal, and colon cancer)  primary neoplasms squamous cell carcinoma: commone...
Article

Superscan

A superscan is an imaging appearance on a Tc-99m diphosphonate bone scan which occurs as a result of a high ratio of bone to soft tissue tracer accumulation. Intense osteoblastic activity in the bones causes diminished renal and background soft tissue uptake. Pathology Etiology This appearanc...
Article

Solid periosteal reaction

Solid periosteal pattern is thought to evolve from single layer and multilayered periosteal reactions, forming a solid layer of mature new bone adjacent to the cortex. It denotes a longstanding pathological process. Differential diagnosis osteoid osteoma osteomyelitis osteosarcoma chondrosa...
Article

Salivary gland tumors

Salivary gland tumors are variable in location, origin, and malignant potential.  Pathology In general, the ratio of benign to malignant tumors is proportional to the gland size; i.e. the parotid gland tends to have benign neoplasms, the submandibular gland 50:50, and the sublingual glands and...
Article

Periosteal reaction

Periosteal reaction is a nonspecific radiographic finding that indicates new bone formation in reaction to the abnormal stimulants. Periosteal reactions may be broadly characterized as benign or aggressive, or more specifically categorized by pattern. Terminology Periosteal reaction is the rec...
Article

Peritoneal calcification

Peritoneal calcification is seen in a limited number of conditions that result in calcification of peritoneal structures. Therefore, the differential diagnosis is small: psammoma bodies in malignancy (most frequently cystadenocarcinoma of the ovary): fine sand-like calcification pseudomyxoma p...
Article

Pancreatic neoplasms

There are numerous primary pancreatic neoplasms, in part due to the mixed endocrine and exocrine components. Classification Classification based on function exocrine: ~99% of all primary pancreatic neoplasms pancreatic ductal adenocarcinoma (commonly known as pancreatic cancer) 90-95%  cyst...
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Pediatric renal tumors and masses

Pediatric renal tumors and masses are another group of diseases (just like cystic renal diseases in both the adult and child) that are bewildering in their number, nomenclature and overlapping findings. Commoner lesions Wilms tumor: common in older children 1-8 years old nephroblastomatosis: ...
Article

Omental cake

Omental cake refers to infiltration of the omental fat by material of soft-tissue density. The appearances refer to the contiguous omental mass simulating the top of a cake. Masses on the peritoneal surfaces and malignant ascites may also be present.  Pathology The most common cause is metasta...
Article

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...
Article

Hypertrophic osteoarthropathy

Hypertrophic osteoarthropathy (HOA) is a syndrome characterized by periosteal reaction of the long bones without an underlying bone lesion. There are a broad range of manifestations, although typically there is symmetrical involvement of the appendicular skeleton. Accompanying abnormal soft tiss...
Article

Cystic (necrotic) lymph nodes

Cystic or necrotic appearing lymph nodes can be caused by a number of infectious, inflammatory or malignant conditions: Systemic squamous cell carcinoma metastases treated lymphoma leukemia plasmacytoid T-cell leukemia acute myeloid leukemia viral lymphadenitis herpes simplex lymphadenit...
Article

Multiple cystic neck lesions (differential)

The differential diagnosis for multiple cystic neck lesions is different to that for a solitary cystic neck mass. Differential diagnosis Cystic neck lesions are seen in: metastatic squamous cell carcinoma: older patient, M>F metastatic papillary thyroid carcinoma: usually a younger patient, ...
Article

Cystic lesions of the pancreas (differential)

The differential for cystic lesions of the pancreas includes: unilocular pancreatic pseudocyst intraductal papillary mucinous neoplasm (IPMN) serous cystadenoma uncommonly uni/macrolocular simple pancreatic cyst cystic neuroendocrine tumor of the pancreas diffuse pancreatic cysts pancrea...
Article

Bat wing opacities (lungs)

Bat wing opacities, also known as butterfly opacities, refer to a pattern of bilateral perihilar lung shadowing. It is classically described on a frontal chest radiograph but can also refer to appearances on chest CT 3,4. Differential diagnosis Bat wing pulmonary opacities can be caused by: p...
Article

Differential for an anterosuperior mediastinal mass

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...
Article

Acute airspace opacification with lymphadenopathy (differential)

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 pulmonary metastases lymphoma/leukemia infection prim...

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