Rhabdomyosarcomas of the genitourinary tract are uncommon tumors occurring in pelvic organs. It is a disease nearly exclusive to the pediatric population.
For a general discussion of this type of tumor, please refer to the article on rhabdomyosarcomas.
The peak incidence of tum...
Rhabdomyosarcomas of the biliary tract are rare tumors, usually identified in children, with a very poor prognosis. They are usually grouped under botryoid rhabdomyosarcomas.
For a general discussion of this type of tumor, please refer to the article on rhabdomyosarcomas.
The ROS1 mutation is a mutation occurring in the ROS1 oncogene on chromosome 6 resulting in a defective receptor tyrosine kinase which has structural similarity to the anaplastic lymphoma kinase (ALK) protein.
It is thought to be present in several cancers of the subtype non-small cell lung can...
Rotational/helical/arc intensity-modulated radiation therapy (IMRT) is the most advanced form of IMRT is conceptually similar to helical or cone-beam CT 1. The radiation beam remains turned on throughout the treatment while the gantry is moved around the patient at variable speed and the multi-l...
Rotter lymph nodes (also known as interpectoral nodes) are lymph nodes located in the interpectoral fascia in Rotter space, between the pectoralis major and pectoralis minor muscles. Their number varies from one to four. They are usually considered to be a separate nodal group from the level I a...
Rubinstein-Taybi syndrome (RTS) is a very rare genetic multi-system disorder primarily characterized by intellectual disability, broad and often angulated thumbs and halluces, and distinctive facial features.
The estimated incidence is 1 in 100,000-125,000 live births 5.
Wilms tumor classically follows a "rule of 10s" 1,2:
up to 10% may have unfavorable histology
10% are bilateral
10% have vascular invasion
10% have calcifications on CT
10% have pulmonary metastases at presentation
Salivary gland tumors are variable in location, origin and malignant potential.
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 ...
Samarium-153 (Sm-153) is a radioisotope used in metabolic radiotherapy for the treatment of pain from bone metastases. It is produced in nuclear reactors, by neutron irradiation of samarium-152 (Sm-152 Sm2O3).
Samarium-153 decays by emitting both beta minus particles and gamma photons with a ch...
Sarcoid-like post-immunotherapy granulomatosis has been reported as an uncommon complication in patients treated with immunotherapy agents such as monoclonal antibodies. It was first reported in TNF inhibitors used to treat rheumatoid arthritis and has also been reported in various immunotherapy...
Gastrointestinal manifestations of scleroderma can occur in up to 90% of patients with scleroderma 2 with the most common site of gastrointestinal involvement being the esophagus. After skin changes and Raynaud phenomenon, gastrointestinal changes are the third most common manifestation of scler...
Screening for breast cancer includes activities which test members of asymptomatic populations for breast cancer. Many advanced countries have breast screening programs. The most widely adopted method for breast cancer screening is mammography.
There are few areas in imaging fraught with more c...
Secondary hepatic involvement with lymphoma (secondary hepatic lymphoma) is common, much more so than primary hepatic lymphoma.
Hepatomegaly with deranged liver function tests is the most common presentation. Jaundice is common. Rarely, patients may present with acute li...
Secondary involvement of the bone with lymphoma, also referred as secondary bone lymphoma, is much more common than primary bone lymphoma, occurring in ~15% of disseminated lymphomas.
Secondary bone lymphoma is defined as lymphoma involving the bone with nodal disease occurring wit...
Secondary involvement of the pleura with lymphoma (secondary pleural lymphoma) is very common, occurring in ~20% of lymphomas. It may be a result of an extension of lymphoma into the visceral or parietal pleura or be a complicating pleural effusion and is a poor prognostic factor.
Secondary malignant cardiac tumors or cardiac metastases refer to a secondary malignant tumor involving any structural component of the heart. It represents spread of a primary neoplasm via lymphatic, haematogenous, or endovascular pathways, or potentially by direct extension from an adjacent ti...
Second branchial cleft cysts are a cystic dilatation of the remnant of the second branchial cleft (see branchial apparatus), and along with second branchial fistulae and sinuses accounts for 95% of all branchial cleft anomalies.
Although a congenital abnormality, they ten...
Selective internal radiation therapy (SIRT), also know as hepatic radioembolization, is a relatively new and developing modality for treating non-resectable liver tumors. The procedure consists of a transcatheter injection of radioactive particles via the hepatic artery.
It is generally consid...
The sentinel lymph nodes (SLNs) are defined as those lymph nodes that directly drain a malignancy, or alternatively can be considered as the first node(s) that a tumor metastasizes to.
History and etymology
"Sentinel node" as the initial draining node of a malignancy was first used in a paper ...
Sézary syndrome (SS) is a type of cutaneous T-cell lymphoma. It is sometimes considered an advanced and leukemic form of cutaneous T-cell lymphoma (CTCL).
It is clinically characterized by an extensive erythematous rash covering most of the body as well as the presence of...
The Siewert-Stein classification of esophageal adenocarcinoma classes these tumors according to their relationship to anatomical landmarks 1. It was initially proposed by Siewert et al in 1996, becoming widely used in predicting lymph node spread and directing optimal management. As of the 7th e...
Sinonasal adenocarcinomas are primary tumors of the sinonasal region with glandular differentiation. They are grossly classified as salivary and non-salivary subtypes. However, generally in the literature and IARC/WHO classification, the term Sinonasal adenocarcinoma refers to non-salivary adeno...
Sinonasal lymphoma refers to the involvement of the nasal cavity and/or paranasal sinuses with lymphoma. It can be primary or secondary.
Presenting symptoms of sinonasal lymphoma are variable but are usually similar to those of benign inflammatory diseases. The clinical s...
Sinonasal mucosal melanoma (SNMM) is a very rare and unique subtype of malignant melanoma.
SNMMs account for ~1% of malignant melanomas and <4% of head and neck cancers 1,2. They affect older patients (60-90 years old) 2. There is a higher incidence in Japan 5.
Skeletal metastases are common and result in significant morbidity in patients with metastatic disease. Although the diagnosis is often straightforward, especially as in many cases there is a well-documented history of metastatic malignancy, sometimes they may mimic benign disease or other prima...
Skeletal muscle metastases are uncommon compared to other sites and are generally seen in the context of widespread metastatic disease.
Post-mortem rates of skeletal metastases vary between 0.03% and 17% 1.
Most commonly asymptomatic 2,3.
Skin cancers refer to malignancies arising from the skin.
This is a general discussion of skin cancers, for discussions of specific skin cancers please refer to individual articles.
Overall, skin cancers are the most common human malignancy 1.
Primary skin malignancy ...
Metastases to the skull are very common in patients with disseminated skeletal metastatic disease, although they are often asymptomatic. For a more detailed general discussion please refer to the article on skeletal metastatic disease.
Skull metastases are seen in ~20% (range 15-2...
Small bowel carcinoid tumors are the most common gastrointestinal carcinoid tumors and most frequently involves the terminal ileum.
Small bowel carcinoid tumors account for ~40% of gastrointestinal carcinoid tumors 1.
Small bowel carcinoids are slow growin...
Small bowel lymphoma is one of the most common small bowel malignancies, accounting for ~25% of all primary small bowel malignancies, and ~40% of all primary gastrointestinal lymphomas.
Small bowel lymphoma is most commonly secondary extranodal involvement in widespread systemic l...
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.
A very rare tumor, it has been estimated at <0.0001% of bladder cancers. It is thought to have...
Small cell lung cancer (SCLC), also known as oat cell lung cancer, is a subtype of bronchogenic carcinoma separated from non-small-cell lung cancer (NSCLC) as it has a unique presentation, imaging appearances, treatment, and prognosis. SCLCs are neuroendocrine tumors of the lung that rapidly gro...
Previously, small cell lung cancer (SCLC) was not staged in the same manner as non-small cell lung cancer (NSCLC), but since 2013 both are staged using the IASLC (International Association for the Study of Lung Cancer) lung cancer staging system (currently in its 8th edition, published in 2016)....
Soap bubble appearance describes:
A multi-loculated bubbly appearance.
In bone refers to :
an expansile lytic lesion with internal trabeculations and preserved cortex, usually of benign nature
May be used to describe more aggressive lesions
The differential includes:
Mnemonics to remember the causes of soft tissue calcification include:
My GHOSTS 1
TIC MTV 2
My: myositis ossificans
S: scleroderma/connective tissue diseases
T: tumoral calcinosis
S: sarcoma (synovial cell)
Soft-tissue sarcomas are a heterogeneous group of malignant tumors of mesenchymal origin (sarcoma) that originate from the soft tissues rather than bone. They are classified on the basis of tissue seen on histology. The commoner sarcomas in the adult and pediatric population are listed below.
Solid lesions with enhancement are by far the most commonly encountered appearance of pituitary region masses.
by far the most common entity
typically enhances less vividly than other entities
elevates the dura of the diaphragma sella (as the origin is wi...
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:
Solid-predominant adenocarcinoma of the lung with mucin production is a histological subtype of non-mucinous invasive adenocarcinoma of the lung.
In 2011, the International Association for the Study of Lung Cancer (IASLC), American Thoracic Society (ATS), and European Respiratory S...
Solitary bone plasmacytomas is an uncommon plasma cell tumor which is localized to bone. They 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 i...
A solitary pulmonary nodule, according to the Nomenclature Committee of the Fleischner Society, is defined as a rounded opacity, well or poorly-defined on a conventional radiograph, measuring up to 3 cm in diameter and is not associated with lymphadenopathy, atelectasis, or pneumonia.
The differential diagnosis of a solitary sclerotic bone lesion is heavily influenced by the age of the patient, and includes:
solitary either because no others are present or no others have been imaged
enostosis (bone island)
Lymphadenopathy is quite common, and it can be very difficult to differentiate malignant lymphadenopathy from reactive nodal enlargement.
Several gray scale and color Doppler features favor malignancy in a lymph node.
Gray scale parameters that favor malignancy
size: larger-more likely malign...
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 gland in cases of prostate cancer.
OAR stands for "organ at risk", and in cases of prostate cancer radiotherapy treatment the rectum is the...
Spermatic cord leiomyosarcomas are uncommon malignant paratesticular masses.
Accounts for ~10% of spermatic cord sarcomas. The average of a patient at presentation is 58 years old (although has been seen as young as 15 years old).
Patients may have left inguina...
Spermatic cord liposarcomas are the most common malignant tumor of the spermatic cord. Most present as painless, slow-growing masses and can be mistaken for inguinal hernias. They are usually well-differentiated and spread by local extension.
In a large population-based registry,...
Spinal astrocytomas are the second most common spinal cord tumor, representing 40% of intramedullary tumors 3. They account for 60% of pediatric intramedullary tumors, making them the most common spinal cord tumor in children 6.
This article specifically relates to spinal astrocytomas. For a di...
The spinal instability neoplastic score (SINS) helps to assess tumor related instability of the vertebral column. It has been shown to useful in guiding the mobilization or operative management of patients with neoplastic spinal disease.
Studies have reported good inter-observer agreement among...
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%)
intramedullary metastases (1%)
Each of these are discussed separately. Below...
Spinal paragangliomas are tumors of neuroendocrine origin that rarely involve the central nervous system, usually the filum terminale and cauda equina. They are indolent and considered WHO grade I lesions 5.
Paragangliomas overall are most commonly located within the adrenal gland (pheochromoc...
Spindle cell carcinomas of the lung correspond to a very rare type of non-small cell lung carcinomas (NSCLC) classified under sarcomatoid carcinomas of the lungs.
Although, in the past, some authors also used the term synonymously with pleomorphic carcinoma of the lung, since the ...
Spitz nevus is a rare benign melanocytic lesion, that shares significant clinicohistological commonality with melanoma and maybe difficult to differentiate 2.
History and etymology
This lesion was described by an American pathologist, Sophie Spitz (1910-1956), who worked at Memorial Sloan-Ket...
Splenic lymphoma, also termed as lymphomatous involvement of the spleen, represents the most common malignancy to involve the spleen. They are commonly secondary, rarely being primary (referred as primary splenic lymphoma).
This article focuses on the location-specific primary and secondary l...
Splenic metastases are relatively rare on imaging, although they are more commonly found on autopsy. Typically they are part of a widespread metastatic disease.
The rate of splenic metastases varies between 1-10% of autopsy studies, depending on whether microscopic or macroscopic ...
Splenomegaly refers to enlargement of the spleen. The upper limit of normal adult splenic length is traditionally cited at 12 cm, but lengths upwards of 14 cm can be seen in normal, taller males 7.
Massive splenomegaly is variably defined, including when the spleen is 5 standard deviations abov...
The split bolus technique is a CT imaging investigation used in patients with hematuria aiming to put together, in a single image acquisition, both the nephrographic and renal excretory phases and thus reducing the radiation dose of the study. It is a CT protocol adopted for some institutions fo...
Squamous cell carcinoma of the larynx is the most common primary malignant tumor that affects the laryngeal framework. Typically it is categorized by the laryngeal subsite affected, which affects presentation, treatment and prognosis.
Males are more affected than females, and usu...
Squamous cell carcinoma (SCC) is one of the non-small cell carcinomas of the lung, second only to adenocarcinoma of the lung as the most commonly encountered lung cancer.
Squamous cell carcinoma accounts for ~30-35% of all lung cancers and in most instances are due to heavy smoki...
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:
stage I: confined to the glans or foreskin
stage II: invasion of penile shaft
Squamous cell carcinoma of the urinary bladder is rare and accounts for only ~3-8% 1,2 of all bladder cancers (90% are transitional/urothelial cell carcinomas) but nevertheless, SCC is the most common type of non-transitional cell carcinoma involving the bladder 2. SCC of the bladder is observed...
Stereotactic body radiotherapy (SBRT), also known as 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.
Stereotactic radiosurgery (SRS) was developed based on patient immobilization techniques, such as headframes. 'Stereotactic' refers to the high precision of the treatment system which allows smaller margins and higher doses per treatment 1. SRS involves a smaller number of treatments (typically...
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...
Sunburst appearance is a type of periosteal reaction giving the appearance of a sunburst secondary to an aggressive periostitis. It should not be confused with the sunburst sign of meningioma vascularity.
The sunburst appearance occurs when the lesion grows too fast and the periosteum does not...
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 obstruc...
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 etiological factors:
diffuse metastatic disease
transitional cell c...
Sweet syndrome (acute febrile neutrophilic dermatosis) is characterized by a constellation of clinical symptoms, physical features, and pathologic findings which include:
tender erythematous skin lesions (papules, nodules, and plaques)
a diffuse infiltrate consisting predo...
Sympathetic chain schwannomas or schwannomas of the cervical sympathetic chain (SCSC) are rare benign nerve sheath tumors. These longitudinally oriented tumors in the perivertebral space rely on anatomical mass effect to differentiate from the main differential masses of vagal schwannoma or spin...
Synchronous breast cancers are two (or more) primary breast cancers that occur in either breast at the same time.
Up to 10% of all breast cancers may be synchronous (particularly found with the use of breast MRI). The occurrence of bilaterality is greatest with invasive lobular c...
The term synchronous is used in oncology to refer to two (or more) independent primary malignancies, when the second (or third, etc.) malignancy arose within six months of the diagnosis of the first malignancy 1,2. These may be in the same, or in different, organs.
Synchronous primary lung carcinoma (SPLC) is a term given to the occurrence of two or more primary lung carcinomas within different portions of the lung in the same time period.
They are thought to the carry the same pathophysiological mechanism as metachronous lung carcinoma (i.e. two or more ...
The syndrome of inappropriate antidiuretic hormone secretion (SIADH or SIAD) (also known as Schwartz-Bartter syndrome) was initially described in patients with lung cancer who developed hyponatremia associated with continued urinary sodium loss. The result is often dilutional hyponatremia in whi...
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...
Synovial sarcomas are relatively common intermediate-to-high grade malignant soft tissue tumors, often with an initial indolent course, affecting young patients, and most commonly involving the soft tissue surrounding the knees.
Synovial sarcomas typically present in adolescents a...
The oncological agent tamoxifen has pro-oestrogenic changes on the endometrium resulting in abnormal growth 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
Tamoxifen is an important anti-estrogen agent used for the treatment of hormone receptor-positive breast cancer and it may induce reversible hepatic steatosis. This is usually transient and may occasionally be associated with hepatic dysfunction. It only rarely leads to cirrhosis 1.
T-cell prolymphocytic leukemia (T-PLL) is a rare and unusual hematological malignancy.
It represents around 2% of all mature lymphocytic leukaemias in adults over the age of 30 1. It usually affects older adults with an average age at presentation being around 65 years. There may ...
Technetium agents based on the technetium-99m (Tc-99m) radioisotope are frequently used agents in medical imaging. A radiopharmaceutical labeled with 99mTc constitutes a coordination complex in which ligands bond to a central atom of 99mTc by coordinate covalent bonds 4 .
The radioactive techne...
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...
Temporal lobe epilepsy (TLE) is the most common type of partial epilepsy, with often characteristic imaging and clinical findings. It is divided into two broad groups:
involves the mesial temporal lobe structures
most frequently due to mesial temporal sclerosis
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
Testicular cancers are the most common neoplasm in men between the ages of 20 and 34 years.
Testicular cancer is uncommon, accounting for less than 1% of all internal organ malignancies 2.
The demographics of affected individuals depends on the age of the histology of the tumor. ...
Testicular embryonal cell carcinoma is a type of non-seminomatous germ cell tumor.
Incidence peaks at around 25-30 years.
It may occur as part of a mixed germ cell tumor (more common and may be present as a component in around 80% of mixed germ cell tumors) or very ra...
Testicular lymphoma is an uncommon 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 concerned ...
Testicular seminomas are the most common testicular tumors and account for ~45% of all primary testicular tumors. 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 mediastina...
Testicular teratoma, unlike ovarian teratoma, is often aggressive in its biological behavior, and often exists as part of testicular mixed germ cell tumors.
Pure testicular teratomas account for only 4-9% of all testicular tumors. A similar number are seen in the context of test...
Thoracic lymph nodes are divided into 14 stations as defined by the International Association for the Study of Lung Cancer (IASLC) 1, principally in the context of oncologic staging. For the purpose of prognostication, the stations may be grouped into 7 zones. The IASLC definitions leave some a...
Thorotrast is a suspension of radioactive thorium dioxide first produced in Germany in 1928 and used as a contrast agent until the 1950s. Its principal use was for cerebral angiography: 90% of the estimated 50,000-100,000 patients treated received it for this purpose. Umbrathor was another thori...
Thymic carcinoma is part of the malignant end of thymic epithelial tumors.
Patients are typically 50 to 70 years of age at presentation 9.
The incidence of paraneoplastic syndromes is thought to be low. At least 10 different histologic variants have been described 4. T...
Thymic hyperplasia is a disorder whereby there is hyperplasia of the thymus gland.
Thymus hyperplasia can be subdivided into two forms:
true thymic hyperplasia
lymphoid thymic hyperplasia
Both true thymic hyperplasia and lymphoid hyperplasia manifest as diffuse symmetric enlarge...
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.
Thyroid lymphoma accounts for <5% of thyr...
Thyroid malignancies are most commonly primary thyroid cancers but can rarely be metastatic deposits.
Thyroid malignancies can be categorized into the following key subtypes:
primary thyroid cancers
papillary thyroid carcinoma: 60-80% of carcinomas
Thyroid scan (thyroid scintigraphy) is a nuclear medicine examination used to evaluate thyroid tissue.
functional status of a thyroid nodule
thyrotoxicosis: differential diagnosis
whole body scan for distant metastases
estimation of local residual thyro...