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.

261 results found
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Primary pulmonary lymphoma

Primary pulmonary lymphomas refer to clonal lymphoid proliferation affecting the lungs without any detectable extrapulmonary involvement. It is much rarer than secondary pulmonary lymphoma and is most frequently represented by lymphoma of B-cell lineage - often marginal zone B-cell lymphoma of m...
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Protein C deficiency

Protein C deficiency is a hypercoagulable state due to reduced activity or an absolute deficiency of protein C, an anticoagulant protein. Protein C deficiency increases the risk of venous thrombosis. Epidemiology The prevalence of protein C deficiency in the general population is around 1 per ...
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Protein S deficiency

Protein S deficiency is a hypercoagulable state associated with increased risk of venous thrombosis (up to 5% of patients with deep venous thrombosis may carry this deficiency). Epidemiology Protein S deficiency may be expected in ≈1 of every 500 people 3. Clinical presentation The spectrum ...
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Pulmonary artery stump thrombosis

Pulmonary artery stump thrombosis describes thrombus formation occurring at the site of the pulmonary arterial stump, a complication following lobectomy or pneumonectomy. It is usually discovered as an incidental finding on routine follow-up chest CT scans. Epidemiology The prevalence of pulmo...
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Pulmonary lymphoma

Pulmonary lymphoma refers to lung parenchymal involvement with lymphoma. Pathology It can be broadly divided as primary or secondary: primary pulmonary lymphoma: (rare) usually non-Hodgkin lymphoma which is limited to the lung with or without mediastinal lymph node involvement and with no evi...
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Pulmonary Pneumocystis jiroveci infection

Pulmonary Pneumocystis jiroveci infection, also referred to as Pneumocystis jiroveci pneumonia (PJP), and previously Pneumocystis carinii pneumonia (PCP), is an atypical pulmonary infection and the most common opportunistic infection in patients with acquired immunodeficiency syndrome (AIDS). T...
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Pyrexia

Pyrexia (or fever) is a clinical sign, indicated by an abnormally elevated core body temperature, which is defined by several medical societies as ≥38.3°C (≥101°F). The temperature elevation may be persistent or episodic. The commonest cause of fever is infection, in one study of hospital inpati...
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Pyrexia of unknown origin

A pyrexia of unknown origin, commonly shortened to PUO and also known as a fever of unknown origin (FUO), was originally defined in 1961 as the condition in which the core body temperature is >38.3oC for a period of three weeks or more, with no diagnosis reached after one week of inpatient inves...
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Rai staging system for chronic lymphoid leukemia

The Rai staging system is one of the two staging systems currently adopted in assessment of chronic lymphocytic leukemia (CLL). It comprises of stages 0 to IV and classifies chronic lymphocytic leukemia into low, intermediate and high-risk categories, which correspond with stages 0, I & II, and...
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Reactive vs malignant lymph nodes (ultrasound features)

A number of sonographic features are helpful in distinguishing reactive versus malignant lymph nodes. Grey scale features Features that favor reactive/infective nodes over malignancy include: nodal matting surrounding soft tissue edema Doppler features Doppler examination is particularly u...
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Reed-Sternberg cells

Reed-Sternberg cells are a classical finding diagnostic of Hodgkin lymphoma. They are giant, multinucleated cells with abundant pale cytoplasm. Reed-Sternberg cells are rare, making up <1% of lymphoid tissue, with the background consisting of lymphocytes, plasma cells, eosinophils and macrophages.
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Renal lymphoma

Renal lymphoma is usually a part component of multi-systemic lymphoma - primary renal lymphoma is unusual. Typical imaging findings are multiple bilateral hypodense or infiltrative renal masses. Epidemiology While renal lymphoma has an autopsy incidence of ~45% (range 30-60%) in lymphoma pati...
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Reticuloendothelial system

The reticuloendothelial system (RES) comprises a number of tissues: spleen bone marrow liver Kupffer cells
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Retrorenal spleen

Retrorenal spleen refers to variant position of the spleen, when its inferior portion lies posterior to the upper pole of the left kidney. This normal variant occurs in ~20% of patients, with the finding more common in patients who lie supine 1. Recognition of this variant is important to avoi...
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Richter transformation

Richter transformation is defined as the development of high-grade non-Hodgkin lymphoma (NHL) in patients with chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL). It has been expanded to include other lymphoid malignancies that develop in CLL patients, including Hodgkin dise...
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Rosai-Dorfman disease

Rosai-Dorfman disease, also known as sinus histiocytosis with massive lymphadenopathy or Rosai-Dorfman-Destombes disease, is a rare benign idiopathic proliferative disease that involves phagocytic histiocytes. Epidemiology The disease predominantly occurs in young adults with a mean age at pre...
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Rubinstein-Taybi syndrome

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. Epidemiology The estimated incidence is 1 in 100,000-125,000 live births 5. Clinical...
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Sclerosing angiomatoid nodular transformation of the spleen

Sclerosing angiomatoid nodular transformation (SANT) of the spleen is a recently recognized, rare, non-neoplastic vascular splenic lesion of uncertain etiology.  Terminology The term SANT first appeared in the literature in a 2004 paper by Martel et al. which examined a series of 25 cases 3. T...
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Secondary hepatic involvement with lymphoma

Secondary hepatic involvement with lymphoma (secondary hepatic lymphoma) is common, much more so than primary hepatic lymphoma.  Clinical presentation Hepatomegaly with deranged liver function tests is the most common presentation. Jaundice is common. Rarely, patients may present with acute li...
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Secondary involvement of the bone with lymphoma

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. Terminology Secondary bone lymphoma is defined as lymphoma involving the bone with nodal disease occurring wit...
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Secondary involvement of the pleura with lymphoma

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.  Epidemiology...
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Secondary organizing pneumonia

Secondary organizing pneumonia (SOP) refers to organizing pneumonia that can be attributed to a specific cause, in contrast to cryptogenic organizing pneumonia (COP). Pathology Etiology SOP can be attributed to the following causes 1: Prior infection bacteria atypical pneumonias (e.g. Legi...
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Secondary pulmonary lymphoma

Secondary pulmonary lymphomas refer to pulmonary involvement with lymphoma when the condition is not limited to the lung and has mediastinal lymph node involvement or evidence of extrathoracic dissemination for at least three months after the initial diagnosis. This is a more common form of pulm...
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Sezary syndrome

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). Clinical presentation It is clinically characterized by an extensive erythematous rash covering most of the body as well as the presence of...
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Sickle cell disease

Sickle cell disease (SCD) (historically known as drepanocytosis) is a hereditary (autosomal recessive) condition resulting in the formation of abnormal hemoglobin (a hemoglobinopathy), which manifests as multisystem ischemia and infarction, as well as hemolytic anemia.  Hemoglobin SC (HbSC) dis...
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Sickle cell disease (abdominal manifestations)

Abdominal manifestations of sickle cell disease (SCD) are wide and can involve many organs. For a general discussion, please refer to sickle cell disease. Splenic splenomegaly may occur transiently with the sequestration syndrome, where rapid pooling of blood occurs in the spleen, resulting ...
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Sickle cell disease (acute chest syndrome)

Acute chest syndrome (ACS) in sickle cell disease is a leading thoracic complication - as well as leading cause of mortality - in those affected by sickle cell disease. The diagnosis is made on the combination of new pulmonary opacity on chest x-ray with at least one new clinical symptom or sign...
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Sideroblastic anemia

Sideroblastic anemia (also known as sideroachrestic anemia) is a rare cause of anemia characterized by the presence of ring sideroblasts rather than normal red blood cells in the bloodstream. Sideroblastic anemia is either congenital or acquired. Clinical presentation Symptoms and signs reflec...
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Small bowel lymphoma

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. Epidemiology Small bowel lymphoma is most commonly secondary extranodal involvement in widespread systemic l...
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Small lymphocytic lymphoma

Small lymphocytic lymphoma (SLL) is a non-Hodgkin lymphoma affecting the B-lymphocytes of the immune system. This condition is now considered different manifestations of the same disease process as chronic lymphocytic leukemia (CLL).  On imaging, they are mostly depicted as lymphadenopathy.  Pa...
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Smoldering multiple myeloma

Smoldering multiple myeloma is a premalignant stage between monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma. Clinical presentation Similar to MGUS patients, smoldering multiple myeloma patients are asymptomatic. Diagnostic criteria The criteria for smoldering m...
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Solitary plasmacytoma with minimal bone marrow involvement

Solitary plasmacytoma with minimal bone marrow involvement refers to a type of plasmacytoma with bone marrow cytology positive for monoclonal plasma cell infiltration. Criteria In order to fulfill the International Myeloma Working Group criteria for the diagnosis of solitary plasmacytoma with ...
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Spleen

The spleen is an organ of the hematological system and has a role in immune response, storage of red blood cells and hematopoiesis. Gross anatomy The spleen is a wedge-shaped organ lying mainly in the left upper quadrant (left hypochondrium and partly in the epigastrium) and is protected by th...
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Splenic artery aneurysm

Splenic artery aneuryms are the commonest visceral arterial aneurysm formation as well as the 3rd commonest abdominal aneurysm (after the aorta and iliac vessels). Aneurysms are usually saccular in configuration and they can either be in the form of a true aneurysm (much more common) or as a pse...
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Splenic biopsy

Percutaneous splenic biopsy, utilizing either ultrasound or CT guidance, is an accurate and reliable method of acquiring splenic tissue for histopathological assessment and has been proposed as an alternative for splenectomy in selected patients. Although the procedure has been historically fea...
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Splenic cyst

Splenic epithelial cysts, also referred as splenic epidermoid cysts or primary splenic cysts, are unilocular fluid lesions with thin and smooth walls and no enhancement. They represent ~20% of cysts found in the spleen, and are usually an innocuous incidental imaging finding. Note that most (~8...
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Splenic embolization

Splenic (artery) embolization is an endovascular technique for treatment of splenic and splenic artery pathology as an alternative to splenic artery ligation or splenectomy. It often results in successfully treating the underlying pathology, while maintaining at least partial splenic function.  ...
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Splenic granulomatous disease

Splenic granulomatous disease refers to sequelae arising from granulomatous infection-inflammation of the spleen.  They are a result of: infective splenic tuberculosis splenic histoplasmosis splenic brucellosis non-infective splenic sarcoidosis Radiographic features General In latent s...
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Splenic hamartoma

Splenic hamartomas are very rare lesions commonly found incidentally on imaging. They are most often solitary but may be present as multiple nodules in patients with tuberous sclerosis or Wiskott-Aldrich syndrome. Terminology  The recently-described sclerosing angiomatoid nodular transformatio...
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Splenic lymphoma

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...
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Splenic metastases

Splenic metastases are relatively rare on imaging, although they are more commonly found on autopsy. Typically they are part of a widespread metastatic disease. Epidemiology The rate of splenic metastases varies between 1-10% of autopsy studies, depending on whether microscopic or macroscopic ...
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Splenic pseudocyst

Splenic pseudocysts, also referred as secondary splenic cysts, are acquired cystic lesions not delineated by a true epithelial wall. They represent the majority of the splenic cystic lesions, corresponding to approximately 80% of them (c.f. splenic epithelial cysts). The main causes are:  splen...
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Splenic trauma

Splenic trauma can occur after blunt or penetrating trauma or secondary to medical intervention (i.e. iatrogenic). The spleen is the most frequently injured internal organ after blunt trauma. Epidemiology In blunt trauma, the spleen can account for up to 49% of abdominal organ injuries 2. Cli...
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Splenomegaly

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...
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Splenunculus

Splenunculi (also known as supernumerary spleens, accessory spleens, or splenules) are small nodules of spleen that are separate from the rest of the organ.  Epidemiology They are common, seen in up to 16% of CTs of the abdomen and up to 30% of autopsies 2.  Pathology Accessory spleens are c...
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Sweet syndrome

Sweet syndrome (acute febrile neutrophilic dermatosis) is characterized 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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Tc-99m HMPAO labeled WBC

Tc-99m HMPAO (hexamethylpropyleneamine oxime) labeled WBC is one of the technetium radiopharmaceuticals used in WBC imaging. There are three potential radiochemical impurities in the 99mTc-HMPAO: a hydrophilic secondary complex, the free pertechnetate and the reduced 99mTc-hydrolyzate. 1The min...
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T-cell prolymphocytic leukemia

T-cell prolymphocytic leukemia (T-PLL) is a rare and unusual hematological malignancy. Epidemiology 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 ...
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Technetium agents

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...
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Testicular lymphoma

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 ...
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Thalassemia

Thalassemia is an autosomal recessive hemoglobinopathy that originated in the Mediterranean region. The genetic defect causes a reduction in the rate of globin chain synthesis which causes the formation of abnormal hemoglobin molecules. The resultant microcytic anemia is the characteristic prese...
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Therapy-related myeloid leukemia

Therapy-related myeloid leukaemias, also referred to as therapy-related myeloid neoplasms, occur as a late complication after cytotoxic therapies (e.g. chemotherapy, immunosuppressive therapy, and radiation therapy) performed to treat other conditions. They represent hematological malignancies w...
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Thrombotic thrombocytopenic purpura

Thrombotic thrombocytopenic purpura (TTP) is a rare but life-threatening condition characterized by thrombocytopenia, microangiopathic hemolytic anemia and end-organ damage. Epidemiology The prevalence of TTP is ten cases per one million people 2. Ninety-percent of cases occur in adulthood and...
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Thymic rebound hyperplasia

Thymic rebound hyperplasia is considered a from of true thymic hyperplasia. Pathology In periods of bodily stress the thymus may acutely shrink to 40% of its original volume (depending on the severity and duration of the stress). During the recovery phase it can grow back to its original size ...
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Tower vertebrae

Tower vertebrae a rare manifestation of sickle cell disease, in which short infarcted vertebrae are seen adjacent to other abnormally grown in height vertebrae.  See also codfish or h-shaped vertebrae anterior vertebral vascular notches vanishing vertebrae
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Transfusion-related acute lung injury

Transfusion-related acute lung injury (TRALI) is defined as non-cardiogenic pulmonary edema temporally-related to transfusion therapy.  It tends to occur within 6 hours after a blood transfusion and requires exclusion of other alternative diagnoses such as sepsis or volume overload.  Radiograp...
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Trousseau syndrome

Trousseau syndrome (not to be confused with Trousseau sign) represents the association between migratory thrombophlebitis and malignancy, particularly mucin-producing tumors; hence one of its other names: cancer-associated thromboembolism 1. History and etymology  Armand Trousseau (1801-1867),...
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Tumors associated with increased erythropoetin

Tumors associated with increased erythropoetin are varied and numerous. Patients will be polycythemic due to erythropoetin secretion. Tumors in this group include: renal cell carcinoma (RCC) 2 hepatocellular carcinoma (HCC) hemangioblastoma
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Twin anemia polycythemia sequence

Twin anemia polycythemia sequence (TAPS) is considered a variant of the twin to twin transfusion syndrome (TTTS). Epidemiology TAPS may occur spontaneously in up to 5% of monochorionic twins and may also develop after incomplete laser treatment in twin-to-twin transfusion syndrome cases 2. Pa...
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Typhlitis

Typhlitis, also called cecitis or neutropenic colitis, is a necrotizing inflammatory condition which typically involves the cecum and, sometimes, can extend into the ascending colon or terminal ileum. Epidemiology Typhlitis was first described in children with leukemia and severe neutropenia (...
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Typical clinical manifestations of multiple myeloma (mnemonic)

The typical clinical manifestations of multiple myeloma can be recalled using the mnemonic: CRAB Mnemonic C: hypercalcemia R: renal failure A: anemia B: bone disease The CRAB mnemonic can help differentiate multiple myeloma from its precursor diseases - monoclonal gammopathy of undetermin...
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Uterine lymphoma

Uterine lymphoma refers to involvement of the uterus with lymphoma. Some authors also place lymphoma of the uterine cervix under this group. Epidemiology It is rare condition with initial uterine involvement occurring in only 1% of patients with lymphoma 3. However, uterine involvement is more...
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Vaginal lymphoma

Vaginal lymphoma can refer to: secondary involvement of the vagina (secondary vaginal lymphoma) from widespread generalized lymphoma relatively commoner usually comprises of diffuse large cell B non-Hodgkin's lymphoma (DLBCL) 2 primary vaginal lymphoma much rarer
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Vanishing vertebrae

Vanishing vertebrae is a rare ischemic manifestation of sickle cell disease, in which a completely infarcted vertebral body literally disappears or vanishes, as a result of infarction. In the few reported cases, the posterior elements remain intact. See also codfish or h-shaped vertebrae ante...
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Vitamin B12 deficiency

Vitamin B12 deficiency, also known as hypovitaminosis B12 or hypocobalaminemia, is not uncommon, with potentially serious sequelae if not adequately treated. Clinical presentation Vitamin B12 deficiency results in a reduction of two metabolic pathways 3:  conversion of L-methylmalonyl coenzym...
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Vitamin B6 deficiency

Vitamin B6 deficiency (also known as hypovitaminosis B6) is rare, as the B6 vitamers are present in many commonly-consumed foodstuffs. It is most commonly seen in the context of chronic ethanol excess, although many other risk factors are known. In children, deficiency may manifest as seizures. ...
Article

Vitamin K

Vitamin K is not a single compound but a family of fat-soluble vitamins essential for normal blood-clotting function and comprises two vitamers that are found naturally: phytomenadione (also known as phylloquinone or K1) and menaquinone (or K2). Menaquinone (K2) is synthesized by normal flora i...
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Von Willebrand disease

Von Willebrand disease (vWD) is the commonest inherited bleeding diathesis but may be acquired. Clinical presentation Bruising and mucosal bleeding are typical presentations, but there is a spectrum of severity. The more residual von Willebrand factor (vWF) a patient has, the less severe the b...
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Waldenström macroglobulinemia

Waldenström macroglobulinemia, previously also known as lymphoplasmacytic lymphoma, is a type of B-cell lymphoma. Terminology Recent publications classify Waldenström macroglobulinemia as a lymphoplasmacytic lymphoma with any level of an IgM paraprotein 10.  Therefore the two entities are not ...
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Wells criteria for pulmonary embolism

The Wells criteria for pulmonary embolism is a risk stratification score and clinical decision rule to estimate the probability for acute pulmonary embolism (PE) in patients in which history and examination suggests acute PE is a diagnostic possibility. It provides a pre-test probability which, ...
Article

White blood cell

White blood cells or leukocytes are one of the main cell types found in normal human blood. They are actually colourless (but appear white on light microscopy) and divided into granular and non-granular types. Types of white blood cell: granular neutrophils eosinophils basophils non-granul...
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WHO classification of tumors of hematopoietic and lymphoid tissues

The World Health Organization (WHO) classification of tumors of hematopoietic and lymphoid tissues is the most widely used pathologic classification system for hematolymphoid neoplasms. The current revision, known as the 4th revised edition, was published in 2016 and supersedes the 4th edition p...
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Widening of the diploic space

Widening of the diploic space refers to expansion of the spongy or cancellous bone between the inner and outer tables of the calvaria. The diploic space is the medullary cavity of the skull, and a location of normal physiologic hematopoiesis in adults. Thus, expansion of this structure most comm...
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Wiskott-Aldrich syndrome

Wiskott-Aldrich syndrome (WAS) is a rare immunodeficiency disease with a characteristic phenotype that includes: X-linked recessive petechiae, bloody diarrhea, epistaxis due to thrombocytopenia with small platelets eczema starts in the first month of life recurrent infections with encapsulat...
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Zebra spleen

Zebra spleen, also referred to as psychedelic spleen or more correctly inhomogeneous splenic enhancement, refers to the transient heterogeneous parenchymal enhancement of the spleen during the arterial or early portal venous phases of contrast enhancement in CT, MRI, or ultrasound imaging. It i...

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