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.

337 results found
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Skeletal muscle metastases

Skeletal muscle metastases are uncommon compared to other sites and are generally seen in the context of widespread metastatic disease.  Epidemiology Post-mortem rates of skeletal metastases vary between 0.03% and 17% 1.  Clinical presentation Most commonly asymptomatic 2,3.  Pathology Com...
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Small bowel lymphoma

Lymphoma of the small bowel is the most common small bowel malignancy, accounting accounts for ~25% of all primary small bowel malignancies and ~40% of all primary gastrointestinal lymphomas. Epidemiology Small bowel lymphoma is most commonly secondary extranodal involvement in widespread syst...
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Small cell carcinoma of the bladder

Small cell carcinomas of the bladder are rare bladder cancers with a poor prognosis. Its appearance overlaps other bladder cancers, in particular, urothelial/transitional cell carcinoma. Epidemiology A very rare tumor, it has been estimated at <0.0001% of bladder cancers. It is thought to have...
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Smoking related lung disease

Smoking related lung diseases are the respiratory manifestations of disease that is related to smoking. Smoking affects the lungs in numerous ways, and can be classified under the following headings: smoking related interstitial lung diseases (SR-ILD) respiratory bronchiolitis respiratory br...
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Soft tissue calcification (mnemonic)

Mnemonics to remember the causes of soft tissue calcification include: My GHOSTS 1 TIC MTV 2 Mnemonic  My GHOSTS My: myositis ossificans G: gout H: hyperparathyroidism O: ochronosis S: scleroderma/connective tissue disease T: tumoral calcinosis S: sarcoma (synovial cell) TIC MTV T: ...
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Solid and enhancing pituitary region mass

Solid lesions with enhancement is by far the most commonly encountered appearance of pituitary region masses. The differential includes :  macroadenoma by far the most common entity typically enhances less vividly than other entities elevates the dura of the diaphragma sella (as the origin i...
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Solid periosteal reaction

Solid periosteal pattern is thought to evolve from single layer and multilayered periosteal reactions, forming a solid layer of new bone adjacent to the cortex. It can be seen in: osteoid osteoma osteomyelitis osteosarcoma chondrosarcoma fibrous dysplasia non-ossifying fibroma osteoblast...
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Solitary bone plasmacytoma

Solitary bone plasmacytomas (SBP) may involve any bone, but they have a predisposition for the red marrow-containing axial skeleton: spinal disease is observed in ~50% (range 34-72%) of cases the thoracic vertebrae are most commonly involved, followed by lumbar, sacral, and cervical vertebrae ...
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Solitary sclerotic bone lesion

The differential diagnosis of a solitary sclerotic bone lesion is heavily influenced by the age of the patient, and includes: sclerotic metastasis when solitary may be the only one visible of many or the only one imaged enostosis (bone island) osteosarcoma calcifying enchondroma osteoblast...
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SpaceOAR

SpaceOAR is a technique in which a physical space is created between the prostate gland and rectum for electron beam radiotherapy targeted to the prostate cancer.  OAR stands for "organ at risk", and in cases of prostate cancer radiotherapy treatment the rectum is the main organ at risk. The in...
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Spinal astrocytoma

Spinal astrocytomas are the second most common spinal cord tumour overall, representing 40% of intramedullary tumours 3. They account for 60% of paediatric intramedullary tumours, making them the most common spinal cord tumour in children 6. This article specifically relates to spinal astrocyto...
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Spinal instability neoplastic score (SINS)

The spinal instability neoplastic score (SINS) helps to assess tumour related instability of the vertebral column. It has been shown to useful in guiding the mobilisation or operative management of patients with neoplastic spinal disease. Studies have reported good inter-observer agreement amon...
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Spinal metastases

Spinal metastases 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%) intramedually metastases (1%) Each of these are discussed separately. Below...
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Squamous cell carcinoma (head and neck)

Squamous cell carcinomas (SCC) of the head and neck are common, being the sixth most common cancer. They can have a cutaneous or mucosal origin. As such there is a wide array of clinical and radiographic manifestations, and are separated into: squamous cell carcinoma of the skin of the head and...
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Squamous cell carcinoma of the lung

Squamous cell carcinoma (SCC) is one of the non-small cell carcinomas of the lung, overtaken by adenocarcinoma of the lung as the most commonly encountered lung cancer.  Epidemiology Squamous cell carcinoma accounts for ~30-35% of all lung cancers and in most instances are due to heavy smoking...
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Squamous cell carcinoma of the oral cavity (staging)

Staging of oral cavity squamous cell carcinoma uses the TNM staging system. Primary tumour staging (T) Tx - tumour cannot be assessed T0 - no evidence of primary tumour Tis - carcinoma in situ T1 - tumour 2 cm or less in greatest dimension T2 - tumour greater than 2 cm and less than 4 cm i...
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Squamous cell carcinoma of the penis (staging)

Squamous cell carcinoma of the penis arises most commonly at the distal end of the penile urethra with local invasion of the glans. In addition to TNM classification, the following staging is used: Staging stage I: confined to the glans or foreskin stage II: invasion of penile shaft stage I...
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Stereotactic ablative radiotherapy

Stereotactic ablative radiotherapy (SABR) is a technique used to treat certain cancers as an alternative to surgical resection. It can be used to treat early lung cancer and hepatocellular carcinoma.
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Stipple sign (transitional cell carcinoma)

The stipple sign refers to the pointillistic end-on appearance on intravenous pyelography or retrograde pyelography of contrast material tracking into the interstices of a papillary lesion. Because the majority of transitional cell carcinomas (TCC) have a papillary configuration, the presence of...
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Superior vena cava obstruction

Superior vena cava (SVC) obstruction can occur from extrinsic compression, intrinsic stenosis or thrombosis. Malignancies are the main cause and are considered an oncologic emergency. Superior vena cava syndrome (SVCS) refers to the clinical syndrome with symptoms that results from this obstruct...
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Superscan

Superscan is intense symmetric activity in the bones with diminished renal and soft tissue activity on a Tc99m diphosphonate bone scan. This appearance can result from a range of aetiological factors: diffuse metastatic disease prostatic carcinoma breast cancer transitional cell carcinoma (...
Article

Sweet syndrome

Sweet syndrome (acute febrile neutrophilic dermatosis) is characterised by a constellation of clinical symptoms, physical features, and pathologic findings which include: fever neutrophilia tender erythematous skin lesions (papules, nodules, and plaques) a diffuse infiltrate consisting predo...
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Synonyms

Synonyms, located below references when in edit mode, are used in a number of scenarios.  To view a YouTube screencast tutorial please click here.  What is a synonym? A synonym is essentially a 'redirect' to an article. This enables links created to article A to pass to article B, provided ar...
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Tamoxifen associated endometrial changes

Tamoxifen has pro-oestrogenic effects on the endometrium and thus is associated with an increased prevalence of: endometrial polyps: occurs in ~8-36% of women in treated 8 endometrial hyperplasia: occurs in ~1-20% of women treated ref cystic endometrial atrophy endometrial carcinoma Epidemi...
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Technique of masking

Masking is very important when viewing mammograms, especially with high-density breasts. It helps the adaptation of the eye to the luminance of the mammograms on the viewbox.                     The technique of masking allows the comparative study of small areas of both breasts and is a featur...
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Terminal ileitis (differential)

The differential diagnosis for a terminal ileitis is quite extensive, and includes: inflammatory bowel disease Crohn's disease (most common) backwash ileitis due to ulcerative colitis infectious colitis Yersinia spp.  Yersinia enterocolitica Yersinia pseduotuberculosis Salmonella spp. C...
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Testicular lymphoma

Testicular lymphoma is an uncommon cause of testicular malignancy. Lymphoma can involve the testes in three ways: primary site of extranodal disease (primary testicular lymphoma) secondary involvement of systemic disease primary manifestation of subclinical systemic disease This article is c...
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Testicular seminoma

Testicular seminomas are the most common testicular tumours and account for ~45% of all primary testicular tumours. This article concerns itself only with testicular seminomas, however, seminomas can arise outside of the testicle most often within the anterior mediastinum, e.g. anterior mediasti...
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Testicular teratoma

Testicular teratoma, unlike ovarian teratoma, is often aggressive in its biological behaviour, and often exists as part of testicular mixed germ cell tumours.   Epidemiology Pure testicular teratomas account for only 4-9% of all testicular tumours. A similar number are seen in the context of t...
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Thymic carcinoma

Thymic carcinoma is part of the malignant end of thymic epithelial tumours. Epidemiology Patients are typically 50 to 70 years of age at presentation 9. Pathology The incidence of paraneoplastic syndromes are thought to be low. At least 10 different histologic variants have been described 4....
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Thymic hyperplasia

Thymic hyperplasia is a disorder whereby there is hyperplasia of the thymus gland.  Pathology Thymus hyperplasia can be subdivided into two forms:  true thymic hyperplasia lymphoid hyperplasia Both true thymic hyperplasia and lymphoid hyperplasia manifest as diffuse symmetric enlargement of...
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Thyroid lymphoma

Thyroid lymphoma is rare, accounting for a minority of both thyroid malignancies and lymphoma in general.  The thyroid may be affected primarily or secondary to lymphoma elsewhere. This article is concerned with primary thyroid lymphoma.  Epidemiology Thyroid lymphoma accounts for <5% of thyr...
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Thyroid scan (I-123)

Thyroid scan (thyroid scintigraphy) is a nuclear medicine examination used to evaluate thyroid tissue.  Clinical indications functional status of a thyroid nodule thyrotoxicosis: differential diagnosis thyroid cancer whole body scan for distant metastases estimation of local residual thyro...
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Thyroid-associated orbitopathy

Thyroid-associated orbitopathy (TAO) is the most common cause of proptosis in adults and is most frequently associated with Graves disease. On imaging, it is characterised by enlargement of the extraocular muscles' bellies (frequently: inferior rectus > medial rectus  > superior rectus) sparing...
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TNM staging system

The TNM system has been widely adopted in many areas as a replacement for idiosyncratic disease specific systems. The number of Ts Ns and Ms depend on the tumour/site but in general: TNM T: Tumour Tx: primary tumour cannot be assessed T0: no evidence of primary tumour Tis: carcinoma in situ...
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Tolosa-Hunt syndrome

Tolosa-Hunt syndrome (THS) is an idiopathic inflammatory condition that involves the cavernous sinus and orbital apex, and is essentially a clinical diagnosis of exclusion. Clinical presentation Clinically it refers to the presence of a painful ophthalmoplegia secondary to surrounding cavernou...
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Tracheal masses

The differential for tracheal masses can be rather wide. For a single mass consider: metastasis  direct invasion from adjacent organ (lung, thryoid,esophagus) distant metastsis ( such as melanoma)  primary neoplasms: squamous cell carcinoma: commonest primary tracheal malignancy 2 ~50 % a...
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Trachelectomy

Trachelectomy (sometimes known as a cervicectomy) refers to removal of uterine cervix.  It is sometimes performed as a uterine sparing surgery for certain cases with cervical malignancy 2-3. When it is performed with curative intent it is often termed a radical trachelectomy and is often accomp...
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Tram-track sign (orbit)

Tram-track sign refers to the parallel thickening and enhancement around the optic nerve, and is most frequently seen in the setting of optic nerve meningioma. It may however also be seen in 1: orbital pseudotumour perioptic neuritis orbital sarcoidosis oribtal leukemia orbital lymphoma or...
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Transcoelomic spread

Transcoelomic spread describes the spread of a malignancy into body cavities that occurs via penetrating the surface of the peritoneal, pleural, pericardial, or subarachnoid spaces. For example, ovarian tumours can spread transperitoneally to the surface of the liver.
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Transitional cell carcinoma (staging)

Staging of transitional cell carcinomas of the urinary tract vary according to the location of the tumour, and are staged using the TNM staging system.  transitional cell carcinoma of the renal pelvis transitional cell carcinoma of the ureter transitional cell carcinoma of the bladder  
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Transitional cell carcinoma of the bladder (staging)

Transitional cell carcinoma of the bladder staging uses the TNM system which has replaced the previously widely used Jewett-Scott-Marshall tumour staging system. It is very similar to the staging of TCC of the renal pelvis and staging of TCC of the ureter. TNM staging T Ta - non-invasive papi...
Article

Transverse rectus abdominis musculocutaneous flap

Transplantation of a transverse rectus abdominis myocutaneous (TRAM) flap is a commonly used surgical procedure for breast reconstruction following mastectomy. An autologous myocutaneous flap consisting of abdominal skin, subcutaneous fat, the rectus abdominis muscle, and adjoining vasculature ...
Article

Tuberculosis (intracranial manifestations)

Tuberculosis of the central nervous system can result from either haematogenous spread from distant systemic infection (e.g. pulmonary tuberculosis) or direct extension from local infection (e.g. tuberculous otomastoiditis). Intracranial manifestations of tuberculosis are protean and can affect...
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Tuberculous cervical lymphadenitis

Tuberculous cervical lymphadenitis, also known as scrofula and King's evil, continues to be seen in endemic areas and in the industrialised world particularly among the immunocompromised. Epidemiology Tuberculous cervical lymphadenitis is the most common manifestation of extrapulmonary tubercu...
Article

Tumour markers

Tumour markers are a group of molecules in serum that are elevated in various malignancies and are often used to monitor treatment response as well as alert for potential progressive disease when in remission. Commonly used markers include: AFP beta-hCG CA 19-9 CA-125 CEA chromogranin A P...
Article

Tumours of the male urethra

Tumours of the male urethra are uncommon. They can be categorised 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

Typhlitis

Typhlitis, also called caecitis or neutropaenic colitis, is a necrotising inflammatory condition which typically involves the caecum and, sometimes, can extend into the ascending colon or terminal ileum. Epidemiology Typhlitis was first described in children with leukaemia and severe neutropae...
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Unilateral axillary lymphadenopathy (differential)

Unilateral axillary lymphadenopathy while being more concerning than bilateral axillary lymphadenopathy can still arise from a various benign as well as malignant causes. Benign mastitis other regional infective causes tuberculosis ipsilateral arm infection, e.g. cellulitis silicone induce...
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Urethral diverticulum

Urethral diverticulum, or urethrocoele, is a focal outpouching of the urethra. It should not be confused with a ureterocoele of the distal ureter. Epidemiology Urethral diverticula occur far more frequently in women than in men and are estimated to occur in 1-6% of women, especially those with...
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Vertebra plana

Vertebra plana or pancake vertebra is the term given when a vertebral body has lost almost its entire height anteriorly and posteriorly, representing a very advanced crush fracture. It can occur with a variety of settings, including: trauma osteoporosis Langerhans cell histiocytosis (LCH) mo...
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Vertebral metastases

Vertebral metastases represent the secondary involvement of the vertebral spine by haematogenously-disseminated metastatic cells. They must be included in any differential diagnosis of a bone lesion in a patient older 40 years. This article will focus only on the metastasis involving the bony s...
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Visceral pleural invasion

Visceral pleural invasion is a feature that can be seen in lung cancers. It is defined as tumour extension beyond the elastic layer of the visceral pleura. It is considered an aggressive sign and one of the most important adverse prognostic factors in non-small cell lung cancers 1. Pathology G...
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Von Hippel-Lindau disease

Von Hippel-Lindau (vHL) disease is characterised by the development of numerous benign and malignant tumours in different organs (at least 40 types 1) due to mutations in the VHL tumour suppressor gene on chromosome 3. Epidemiology The disease is rare with an estimated prevalence of 1:35,000-5...
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WHO classification of anal margin tumours

The WHO classification of anal margin tumours or perianal skin tumours is: intraepithelial tumours Bowen disease (precursor of squamous cell carcinoma) Paget's disease (precursor of adenocarcinoma) invasive tumours squamous cell carcinoma adenocarcinoma basal cell carcinoma  verrucous ca...
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WHO classification scheme for thymic epithelial tumours

The WHO classification scheme for thymic epithelial tumours is one of many classifications systems for thymoma and related tumours, and classifies them according to histology: type a medullary thymoma spindle cell thymoma type ab: mixed thymoma type b1: lymphocyte rich predominantly cortic...
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Wilms tumour (staging)

Wilms' tumour staging is largely anatomical and relates to the invasion and spread of the tumour. Where there is invasion or metastasises, prognosis is poorer. Wilms tumour, is one of the more common childhood malignancies. stage I confined to kidney complete resection possible stage II loc...
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Xanthogranulomatous cholecystitis

Xanthogranulomatous cholecystitis is an uncommon inflammatory disease of the gallbladder which may be difficult to differentiate from malignancy, both on imaging and pathologically. It is characterised by presence of multiple intramural nodules. Epidemiology It is seen predominantly in female ...

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