There are numerous fat-containing renal lesions, including:
renal cell carcinoma
renal or perirenal lipoma/liposarcoma
Non-mass lesions may also occasionally contain fat:
renal junction line
fat in a renal scar
renal sinus lipomatosis
The differential of a fat containing solitary pulmonary nodule is very narrow.
In a well circumscribed smooth or lobulated mass (especially if it has been largely stable in size over time) presence of fat is essentially pathognomonic of a pulmonary hamartoma, and usually not further assessment ...
There is a long list of fat containing thoracic lesions. They may involve the mediastinum, lung, pleura or chest wall.
Differential diagnosis includes:
intrapulmonary: fat containing pulmonary lesions
Fatty mediastinal masses are relatively uncommon, and the differential diagnosis is brief, including 1-4:
benign mature teratoma
extravasation of lipid-rich hyperalimentation fluid 3
fibrofatty replacement of the central portion of mediastinal l...
Female infertility is common, and can be due to a number of factors. Radiology often plays a key part of the work-up.
Often more than one factor (including male infertility) is the cause of infertility, some of the common causes are listed below 1-3:
age > 35 years
Femoral anteversion refers to the orientation of the femoral neck in relation to the femoral condyles at the level of the knee. In most cases, the femoral neck is oriented anteriorly as compared to the femoral condyles. In the case of posterior orientation, the term femoral retroversion is also ...
Fetal anterior abdominal wall defects can occur with a number of pathologies.
limb body wall complex
omphalocoele-radial ray (ORR) complex
Pentalogy of Cantrell
Fetal ascites refers to the accumulation of free fluid in the fetal abdomen. It is often considered under the same spectrum of hydrops fetalis.
any condition that results in hydrops fetalis
additional causes include
bowel perforation (e.g. meconium peritonitis...
Fetal biophysical profile score (BPS or BPP) refers to assessment of four discrete biophysical variables by ultrasound. It is a standard tool in antepartum fetal assessment. It is usually assessed after 28 weeks of gestation.
The ultrasound variables...
Fetal bowel dilatation can occur from many causes, which include:
intestinal atresias: mainly distal
apple-peel intestinal atresia
megacystis microcolon hyperperistalsis syndrome 4
congenital chloride d...
Fetal brain tumors are uncommon and tends to have very different pathological spectrum than that observed in adults; in order of decreasing frequency:
fetal intracranial teratoma: most common tumor by far
astrocytoma/glioblastoma: next most common
craniopharyngioma: papillary type
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 ...
Fetal chylothorax is defined as the presence of lymphatic fluid within the pleural cavity of the fetus.
may show echogenic fluid in the pleural cavities
Fetal clenched hands are an antenatal ultrasound observation where the fetal hands are in a constant (permanently) clenched position as if being unable to extend.
Some authors 3 suggest that the abnormal posture results in part from:
muscle variations along the radial margin of the...
Fetal death in utero (FDIU), also known as intrauterine death (IUD), is the term used when the death of a fetus occurs after the 20th week of pregnancy. Prior to this, it is considered a miscarriage.
1% of normal, uncomplicated pregnancies end in fetal death. In ~15% of FDIU, no c...
Fetal intra-abdominal cystic lesions can arise from a number of physiological and pathological causes.
fetal gastric dilatation / fetal gastric bubble (can be pathological if there is a gastric outlet obstruction
normal fetal gallbladder
No color flow
Fetal intracranial calcification refers to intracranial calcification detected in utero. This can arise from a number of pathologies which include:
in utero infections
fetal toxoplasmosis infection: calcification tends to be randomly distributed
fetal cytomegalovirus infection1: calcificatio...
Fetal intracranial cystic lesions can arise from a number of pathologies, including:
fetal arachnoid cyst
fetal choroid plexus cyst
fetal connatal cyst
fetal porencephalic cyst
fetal interhemispheric cyst
fetal subependymal cyst
dorsal cyst of holoprosencephaly
Fetal intracranial hemorrhage may occur either within the cerebral ventricles, subdural space or infratentorial fossa.
Hemorrhages can occur in a number of situations:
mechanical trauma, e.g. maternal abdominal blunt or birth trauma
severe fetal hypoxia
background fetal thrombocyt...
Fetal intrahepatic calcification can be a relatively common finding. Calcifications in the liver can be single or multiple and in most cases in which isolated hepatic calcific deposits are detected, there is usually no underlying abnormality.
The presence of isolated intrahepatic calcification ...
Fetal limb bowing may be a feature of skeletal dysplasia, particularly if it is severe. A mild degree of lateral bowing to femur can occur as part of normal variation.
Conditions associated with fetal limb bowing include:
camptomelic dysplasia 1
thanatophoric dysplasia 2: particularly type I
Fetal pleural effusions (FPE) refer to an accumulation of pleural fluid in utero. It can refer to either a fetal chylothorax or a fetal hydrothorax.
A fetal pleural effusion can occur as part of hydrops fetalis, in association with other anomalies without hydrops or in isolation - pr...
Fetal pyelectasis refers to a prominence of the renal pelvis in utero that is a relatively common finding, which in the majority of cases resolves spontaneously.
Please refer to the article on fetal hydronephrosis for a continued discussion on this matter.
Although there is an ...
Fetal rib fractures can be caused by certain skeletal dysplasias. These include:
osteogenesis imperfecta: type II - one of the classical causes of fetal rib fractures
achondrogenesis: type Ia - Houston-Harris sub type
Although rare, a number to tumors may be diagnosed antenatally. These fetal tumors are a diverse and a unique group of conditions, and include:
neuroblastoma: most common tumor overall
head and neck teratoma/epignathus
Fetal ventriculomegaly (ventricle width >10 mm) is an important finding in itself and it is also associated with other central nervous system abnormalities. For more information, see the main article fetal ventriculomegaly.
Fetal ventriculomegaly can be thought of in ter...
Fibromatosis refers to a wide range of soft tissue lesions that share an underlying histopathologic pattern of fibrous tissue proliferation. They can occur in a variety of anatomic sites (e.g. musculoskeletal, abdominopelvic, breast, etc.) and also vary in their behavior, ranging from indolent/b...
Fibropolycystic liver disease is a collective term for a group of congenital liver and biliary abnormalities resulting from abnormal development of the ductal plates. Disease in this group include:
congenital hepatic fibrosis
autosomal dominant polycystic disease
Fibrous hamartoma of infancy is a rare benign tumor of the subcutaneous tissues seen in children. More than 90% of cases present in the first year of life with up to 25% being congenital 1.
There is a reported male:female ratio of 2:1 but the exact incidence is unknown 2.
The differential for fibrous lesions is wide and includes:
osteofibrous dysplasia / adamantinoma
malignant fibrous histiocytoma / fibrosarcoma
Floating meniscus (also known as meniscal avulsion) occurs in acute traumatic settings when the meniscotibial coronary ligaments get disrupted leading to avulsion of the meniscus from the tibial plateau.
Displacement of the meniscus for 5 mm or more from the tibial p...
Flowing ossifications are seen in diffuse idiopathic skeletal hyperostosis (DISH).They are defined as heterotopic ossifications involving the anterior longitudinal ligament, paraspinal connective tissues and annulus fibrosus of at least four contiguous vertebral bodies and are originally describ...
Fluid-fluid level containing bone lesions are best seen on MRI, although with narrow window width they can also be appreciated on CT.
Their prevalence is estimated at ~3% of bone and soft tissue tumors 1.
Their presence is non-specific, as they are seen in...
Focal calvarial thinning can result from a number of causes. They include:
bilateral thinning of the parietal bones (normal variant) most common
mega cisterna magna
peripherally located tumors (e.g. oligodendroglioma)
Focal gallbladder wall thickening is an imaging finding that includes both benign and malignant etiologies.
gallbladder carcinoma: look for infiltration into adjacent organs, metastases, lymphadenopathy, bile duct dil...
Focal hypodense hepatic lesions on a non-contrast CT scan can result from a number of pathological entities, including:
biliary hamartoma: von Meyenberg complexes 2
hepatoma/hepatocellular carcinoma (HCC)
Foregut duplication cysts are a type of congenital duplication cyst. They are sometimes classified under bronchopulmonary foregut malformations.
Entities classified as foregut duplication cysts include:
other enteric cysts
esophageal duplication cysts
Fracture-a-la-signature (or signature fracture) is another term used to described a depressed skull fracture.
Fracture-a-la-signature derives its name from forensic medicine because the size and shape of a depressed skull fracture may give information on the type of weapon used. It can be a si...
Fracture-dislocations of the radius and ulna illustrate the importance of including the joint above and below the site of injury on radiographic assessment.
Most forearm fractures (60%) include fracture of the distal radius as well as an ulnar fracture. In some cases, there is associated disloc...
Fractures of the thumb are important due to huge impact the thumb has on the overall function of the hand, an understanding of the types of fractures that occur is important, as treatment varies with fracture type.
Metacarpal fractures include:
Fragility fractures are the result of forces that would not fracture a normal bone. They can occur in the context of very low energy (i.e. minimal) trauma such as falling from standing height, or they may be no identifiable preceding trauma. There is overlap between fragility fractures and insuf...
Free silicone breast injections (silicone mastopathy) are an alternative form of breast augmentation to breast implants, although they have serious adverse effects and are banned in many countries.
There are similar features to that of free silicone from breast implant r...
Frontal bossing is a calvarial radiographic feature where the front of the skull appears protruding anteriorly. It is best appreciated on a sagittal or lateral image.
This feature can be seen in many conditions (in alphabetical order):
Gallbladder adenomas are uncommon gallbladder polyps that, although benign, have a premalignant behavior.
As the distinction of adenomas and intracholecystic papillary-tubular neoplasms (ICPN) is not entirely clear, with important overlap between both entities, some authors have p...
Gallbladder cholesterol polyps are the most common subtype of gallbladder polyps, representing more than 50% of all polyps. They are frequently seen in middle-aged women and are benign lesions, with no malignant potential.
For further details, please refer to the parental article on gallbladde...
Gallbladder ghost triad is a term used on ultrasound studies when there is a combination of three gallbladder features on biliary atresia:
atretic gallbladder, length less than 19 mm
irregular or lobular contour
lack of smooth/complete echogenic mucosal lining with an indistinct wall
Gallbladder inflammatory polyps are a benign subtype of gallbladder polyps, representing ~10% of all polyps. They appear as a result of chronic inflammation (chronic cholecystitis).
For further details, please refer to the parental article on gallbladder polyps.
Thought to develop...
Gallbladder sludge, also known as biliary sand, biliary sediment, or thick bile, is a mixture of particulate matter and bile, normally seen as a liquid-liquid level in the gallbladder on ultrasound, corresponding to the precipitate of bile solutes.
These precipitates consist of chol...
Gamuts in radiology refer to the complete list of differential diagnoses for any radiological finding.
We include gamut as a category for articles on Radiopaedia.org to cover sections which cover multiple diagnoses, findings or systems.
History and etymology
According to Maurice Reeder, writi...
There numerous causes of gas in the bladder. In the hospital setting by far the most common is the recent placement of an indwelling urinary catheter. Other causes include 1:
indwelling urinary catheter is by far the most common cause
A gasless abdomen refers to a paucity of gas on abdominal radiography, and the specific cause can usually be identified when the patient's history is known. Common causes include:
small bowel obstruction
A gastric band is a surgically placed device, used to assist in weight loss. It is now the most popular form of bariatric surgery, largely replacing gastric bypass procedures 1.
Performed laparoscopically, a silicone band device is placed around the stomach to reduce its volume. The band is adj...
Gastric band malposition is an early complication from laparoscopic gastric band procedures which are performed for obesity. It can occur as in isolation or with other gastric band complications.
As surgical experience of lap gastric banding has accumulated, it has become a relatively rare comp...
Gastric band erosion or penetration is a potentially serious complication following laparoscopic gastric band surgery for obesity.
Gastric band erosion is a delayed complication observed in between 0.3-14% of patients 1,2.
Patients often present non-specif...
Gastric diverticula are sac-like projections that usually originate from the gastric fundus, most commonly on the posterior surface. They are the least common gastrointestinal diverticulum.
Gastric diverticula are rare and commonly detected incidentally. The incidence varies from...
Gastric outlet obstruction is a syndrome resulting from mechanical obstruction of stomach emptying.
Gastric outlet obstruction can be due to malignant or benign causes.
adenocarcinoma (second most common 4)
lymphoma (less commonly than other malignancies ...
The gastrinoma triangle, also known as Passaro's triangle, is an anatomical area in the abdomen, from where the majority (90%) of gastrinomas are thought to arise.
The triangle is formed by joining the following three points:
superiorly: confluence of the cystic and...
The causes of generalized increase in bone density in adult patients can be divided according to broad categories:
myeloproliferative disorders: myelosclerosis
marrow cavity is narrowed by endosteal new bone
patchy lucencies due to persistence of fibrous tissue (generalized osteopenia in the...
The causes of generalized increased bone density in pediatric patients can be divided accodring to broad categories of cause :
dense metaphyseal bands
cortex and flat bones may also be slight...
Causes of generalized increased liver echogenicity include:
diffuse fatty infiltration
cirrhosis: can be coarsened as well
chronic hepatitis 3: can be coarsened as well
diffuse infiltration or deposition
Generalized osteopenia refers to osteopenia diffusely affecting the bones.
The differential diagnosis is wide and includes:
osteoporosis: decreased osteoid production
osteomalacia: undermineralisation of osteoid
The list of causes of a generalized periosteal reaction overlaps that of symmetrical periosteal reaction, and includes 1,2:
vascular stasis (common)
infantile cortical hyp...
Causes of generalized reduction of liver echogenicity on ultrasound include:
diffuse malignant infiltration
generalized increase in liver echogenicity
hepatic attenuation on CT
Gibbus deformity is a short-segment structural thoracolumbar kyphosis resulting in sharp angulation.
There are a number of causes which can be divided into congenital and acquired.
cretinism (congenital hypothyroidism)
Glass foreign bodies may be present if they are ingested, inserted or as a result of an injury.
The prevalence of glass foreign bodies in wounds from injury has been recorded at a rate of 1.5% in superficial (subcutaneous) wounds and 7.5% of deeper wounds 1.
Glycogen storage disease (GSD) refers to a number of syndromes which are characterized by a defect in synthesis, metabolism or storage of glycogen.
There are many types of GSD:
type I: von Gierke disease
type II: Pompe disease
type III: Cori or Forbes disease
type IV: Andersen di...
Gonadal dysgenesis refers to a spectrum of anomalies with abnormal development of the gonads. It falls under the even broader group of disorders of gender development.
In many cases the gonads are replaced by fibrous tissue.
complete gonadal dysgenesis (CGD) / Swyer syndro...
Gracile bones refer to changes in the skeleton in which the bones are more slender than usual (over-tubulated) and occasionally deformed in other ways such as being abnormally curved. This may occur in a number of disorders and can occur with or without fractures.
Granular mucosal pattern of the esophagus represents very fine nodularity of the esophageal mucosal surface. This finding is nonspecific and may represent:
reflux esophagitis (most common)
superficial spreading esophageal carcinoma...
Granulomatous lung disease refers to a broad group of infectious and non-infections conditions characterized by the formation of granulomas.
The spectrum includes
pulmonary non-tuberculous mycobacterial infection
Gravity dependent atelectasis refers to a form of lung atelectasis which occurs in the dependent portions of the lungs due to a combination of reduced alveolar volume and increased perfusion. Being due to gravity, it usually has a dependent and subpleural distribution. It is very commonly seen i...
Grey-white differentiation refers to the appearance of the interface between cerebral and cerebellar white matter and grey matter on brain CT and MRI.
The term is most often used when trying to differentiate cytotoxic from vasogenic edema.
cytotoxic edema (see ionic edema), where there is a l...
Ground-glass opacification/opacity (GGO) is a descriptive term referring to an area of increased attenuation in the lung on computed tomography (CT) with preserved bronchial and vascular markings. It is a non-specific sign with a wide etiology including infection, chronic interstitial disease an...
The clinical history will nearly always lead to a short differential or the answer. Show off to the examiner that you have a structured approach to reporting and managing the patient.
uterus: size, version and shape (normal or variant which you should elaborate on and say w...
Gynecomastia refers to a benign excess of the male breast tissue, that is usually reversible. It is not a risk factor per se for developing male breast cancer.
While it can occur at any age, it tends to have greater prevalence in two groups: adolescent boys and older men (some pub...
Hematospermia (less commonly hemospermia) refers to the presence of blood in semen or ejaculatory fluid. It is a symptom that can cause great anxiety in patients despite usually being of benign etiology.
urogenital infections including sexually transmitted disease, ...
Hemobilia refers to the presence of blood in the biliary tree.
The classical clinical triad, only seen in ~50% of cases, consists of:
melena (i.e. upper gastrointestinal bleeding)
iatrogenic: surgical or percutaneous proced...
Hemolytic anemia is a form of anemia where red blood cells (RBCs) are destroyed either intravascularly or extravascularly.
The patient presents with anemia and jaundice. Diagnosis is based on several laboratory parameters 1:
increased unconjugated biliru...
Hemopericardium refers to the presence of blood within the pericardial cavity, i.e. a sanguineous pericardial effusion. If enough blood enters the pericardial cavity, then a potentially fatal cardiac tamponade can occur.
There is a very long list of causes 1,4 but some of ...
Hemoperitoneum is the presence of blood within the peritoneal cavity.
penetrating or non-penetrating abdominal trauma (often with associated organ injury) 1
ruptured ectopic pregnancy
ovarian cyst rupture
aneurysm or pseudoaneurysm rupture
Hemopneumothorax (or, less commonly, pneumohemothorax) is a term given when there is concurrent presence of a hemothorax and well as a pneumothorax. It is a variant of a hydropneumothorax.
Approximately 5% of patients with pneumothorax will have concomitant hemothorax 6 .
Hemoptysis refers to coughing out blood. Generally, it appears bright red in color as opposed to blood from the gastrointestinal tract which appears dark red. It is considered an alarming sign of a serious underlying etiology.
Massive hemoptysis is referred to as expectoration of >...
Hemosiderosis is a general term referring to the accumulation of hemosiderin, which particularly occurs in the reticuloendothelial system (RES) and does not cause organ damage.
Some causes include:
mainly depositional siderosis in RES
if >40 units transfused:...
Hemothorax (plural hemothoraces), or rarely hematothorax, literally means blood within the chest, is a term usually used to describe a pleural effusion due to accumulation of blood. If a hemothorax occurs concurrently with a pneumothorax it is then termed a hemopneumothorax.
A tension hemothor...
Hangman fracture, also known as traumatic spondylolisthesis of the axis, is a fracture which involves the pars interarticularis of C2 on both sides, and is a result of hyperextension and distraction.
Post-traumatic neck pain after a high-velocity hyperextension injury is ...
Haustral markings are the radiological appearance of the haustral folds within the colon. Disappearance of the haustral folds results in the lead pipe appearance of ulcerative colitis.
There are many thoracic complications that can occur following hematopoietic stem cell transplantation. These can precipitate during various stages following transplantation and can be either infectious or noninfectious.
Complete white-out of a hemithorax on the chest x-ray has a limited number of causes. The differential diagnosis can be shortened further with one simple observation: the position of the trachea. Is it central, pulled or pushed from the side of opacification? Is there pulmonary volume loss or vo...
Hepatic attenuation on CT, reflected by Hounsfield values, depends on a combination of factors including the presence or absence, as well as the phase, of IV contrast administration.
Allowing for all these factors, the mean unenhanced attenuation value is around 55 HU 4.
A hepatic lymphangioma is a rare benign condition that corresponds to focally dilated lymphatic channels in the liver.
Most cases are asymptomatic.
A lymphangioma is a benign lesion that can occur at almost any location in the body. Hepatic involvement is les...
Hepatic osteodystrophy is an often forgotten metabolic bone disease seen in patients with chronic liver disease, in particular cirrhosis, primary biliary cirrhosis, and primary sclerosing cholangitis. These patients have increased risk factors for developing osteoporosis such as hypogonadism, al...
Hepatisation of the gallbladder is a sonographic entity in which the gallbladder lumen is entirely filled with tumefactive sludge giving the gallbladder a similar appearance to liver parenchyma. It is one of the causes of non-visualization of the gallbladder on sonography.
In the set...
Hepatolithiasis is the presence of bile duct stones within the intrahepatic bile ducts, specifically before the confluence of the right and left hepatic ducts.
Hepatolithiasis is common Asia and the Pacific, with a prevalence of ~40%. It is rare in the West with a prevalence of ~...