Renal osteodystrophy (ROD), also known as uremic osteopathy, is the constellation of musculoskeletal abnormalities that occur in patients with chronic renal failure, due to concurrent and superimposed:
osteomalacia (adults) / rickets (children)
secondary hyperparathyroidism: abnormal calcium a...
Response evaluation criteria in solid tumors or RECIST refers to a set of published rules used to assess tumor burden in order to provide an objective assessment of response to therapy. They were initially introduced in 2000 and have undergone subsequent revision in 2009 (RECIST 1.1). For the ev...
Retroperitoneal leiomyosarcoma, leiomyosarcoma arising within the retroperitoneum, is one of the commonest primary retroperitoneal neoplasms. The retroperitoneum is considered the most common extra uterine site for leiomyosarcoma.
Symptoms are often non-specific with abd...
Rhabdoid meningioma is a rare and aggressive subtype of meningioma, it is classified as WHO grade III. Rhabdoid morphology is associated with a poor prognosis, regardless of tumor histogenesis. It resembles other types of rhabdoid tumors with a great tendency for recurrence 1,2. Extensive necros...
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.
Rubinstein-Taybi syndrome (RTS) is a very rare genetic multi-system disorder primarily characterized by mental retardation, broad and often angulated thumbs and halluces, and distinctive facial features.
The estimated incidence is 1 in 100,000-125,000 live births 5.
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...
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...
Pulmonary manifestations of scleroderma are demonstrated histologically in 90% of patients with scleroderma. It is a leading cause of mortality and at autopsy. The lung is reportedly involved in close to 100% of cases. However, only 25% of patients will present with respiratory symptoms or demon...
Secondary cardiac neoplasm or cardiac metastasis refers 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 tissue 5....
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 organising pneumonia (SOP) refers to organising pneumonia that can be attributed to a specific cause, in contrast to cryptogenic organising pneumonia (COP).
SOP can be attributed to the following causes 1:
atypical pneumonias (e.g. Legi...
Second branchial cleft cysts are a cystic dilatation of the remnant of the 2nd branchial apparatus, and along with 2nd branchial fistulae and sinuses accounts for 95% of all branchial cleft anomalies.
Although a congenital abnormality, they tend to present in early adulth...
Selective internal radiation therapy (SIRT), also know as hepatic radioembolisation, 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...
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 metastasises to.
History and etymology
"Sentinel node" as the initial draining node of a malignancy was first used in a paper writ...
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 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 the most common small bowel malignancy, accounting accounts 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 ly...
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...
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)
Mnemonics to remember the causes of soft tissue calcification include:
My GHOSTS 1
TIC MTV 2
My: myositis ossificans
S: scleroderma/connective tissue disease
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 is 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 wit...
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:
Solitary bone plasmacytomas is an uncommon plasma cell tumor which is localised 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 favour malignancy in a lymph node.
Gray scale parameters that favour malignancy
size: larger-more likely mali...
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 overall, 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. ...
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%)
intramedually 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 (pheochromo...
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 is a term which refers to enlargement of the spleen. The normal adult splenic length upper limit is usually around 12-15 cm. It can also be helpful to know how to calculate splenic index, volume and mass by CT and MR techniques. Massive splenomegaly is a term used when the spleen we...
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...
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, overtaken by 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 smoking...
Staging of oral cavity squamous cell carcinoma uses the TNM staging system.
Primary tumor staging (T)
Tx - tumor cannot be assessed
T0 - no evidence of primary tumor
Tis - carcinoma in situ
T1 - tumor 2 cm or less in greatest dimension
T2 - tumor greater than 2 cm and less than 4 cm in gre...
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
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.
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...
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 aetiological factors:
diffuse metastatic disease
transitional cell carcinoma (...
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...
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...
Syndrome of inappropriate antidiuretic hormone secretion (SIADH or SIAD) was described in patients with lung cancer who developed hyponatremia associated with continued urinary sodium loss. The result is often dilutional hyponatremia in which the sodium remains normal but total body fluid increa...
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...
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
T-cell prolymphocytic leukemia (T-PLL) is a rare and unusual haematologic 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 b...
Technetium agents based on the technetium-99m (Tc-99m) radioisotope are frequently used agents in medical imaging. The radioactive technetium radiotracer can be chelated to a number of different compounds to create specific radiopharmaceuticals and optimise the functional imaging of various stru...
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...
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 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...
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-associated orbitopathy is the most common cause of proptosis in adults and is most frequently associated with Graves disease. On imaging, it is characterized by bilateral and symmetrical enlargement of the extraocular muscle bellies. The typical distribution is inferior rectus > medial r...
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...
The TNM system has been widely adopted in many areas as a replacement for idiosyncratic disease specific systems. The precise details depend on the primary tumor site and/or histology but in general:
Tx: primary tumor cannot be assessed
T0: no evidence of primary tumor
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.
Clinically it refers to the presence of a painful ophthalmoplegia secondary to surrounding cavernou...
The TP53 gene, located on chromosome 17, is a tumor suppressor gene, responsible for the production of the p53 protein, a transcription regulatory protein which works in concert with a number of other proteins, together forming the p53 pathway 1,2.
Inherited mutations in this gene result in the...
The differential for tracheal masses can be rather wide.
For a single mass consider:
direct invasion from adjacent organ (lung, thyroid, esophagus and larynx)
distant metastasis (e.g. melanoma, breast, renal and colon cancer)
squamous cell carcinoma: commone...
Trachelectomy (sometimes known as a cervicectomy) refers to the removal of the uterine cervix.
It is sometimes performed as a uterine-sparing surgery for certain cases with cervical malignancy 2-3. When it is performed with the curative intent it is often termed a radical trachelectomy and is ...
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:
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 tumors can spread transperitoneally to the surface of the liver.
Transitional cell carcinoma of the bladder staging uses the TNM system which has replaced the previously widely used Jewett-Scott-Marshall tumor staging system. It is very similar to the staging of TCC of the renal pelvis and staging of TCC of the ureter.
Ta: non-invasive papill...
Staging of transitional cell carcinomas of the urinary tract vary according to the location of the tumor, 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
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 ...
Trousseau syndrome (not to be confused with Trousseau sign) represents the association between migratory thrombophlebitis and malignancy; hence one of its other names: cancer-associated thromboembolism.
History and etymology
Armand Trousseau (1801-1867), was a French physician who was the fir...
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...
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.
Tuberculous cervical lymphadenitis is the most common manifestation of extrapulmonary tubercu...
Tumor 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 (alpha fetoprotein)
Tumors of the male urethra are uncommon. They can be categorized both on the grounds of histology and location.
squamous cell carcinoma of the urethra: 80%
urothelial/transitional cell carcinoma of the urethra: 15% (predominantly posterior urethra)
adenocarcinoma of the urethra: 5%...