Porphyrias are a group of rare metabolic diseases in which heme metabolism is altered.
Porphyria is rare, with some forms being extremely rare. Estimates for the prevalence of the disease vary in the literature and could reflect differing geographic distribution and/or incomplete ...
A mnemonic to remember the radiological features of hemochromatosis is:
P's for primary and S's for secondary
P: parenchymal (liver, myocardium, thyroid and synovium)
P: poor liver (organ dysfunction and malignancy)
Primary bone (skeletal/osseous) lymphoma (PBL) is a less common manifestation of lymphoma than secondary involvement from disseminated lymphoma. It is rare, accounting for <5% of bone tumors and <1% of non-Hodgkin lymphoma.
PBL is defined as the presence of lymphoma isolated to one...
Primary cutaneous lymphomas represent a group of extranodal non-Hodgkin lymphomas (T- or B-cell) primarily confined to the skin with no evidence of extracutaneous disease at the time of diagnosis (cf. secondary involvement of the skin).
Mycosis fungoides is the most prevalent type of primary c...
Primary effusion lymphoma is a rare form of non-Hodgkin lymphoma (diffuse large cell B cell lymphoma) characterized by malignant fluid accumulation in the absence of lymphadenopathy.
Typical sites of accumulation include
Primary hepatic lymphoma (PHL) is rare, with roughly 100 described cases. If it is being considered as a diagnosis, distal lymphadenopathy, splenomegaly, bone marrow disease, and leukemia should not be present for at least 6 months after the liver tumor is detected (see: secondary hepatic lympho...
Primary hypercoagulable states are those situations where patients have laboratory (genetic) abnormalities resulting in clinical conditions that are associated with an increased risk of thrombosis (prothrombotic states) or have recurrent thrombosis without recognisable predisposing factors (thro...
Primary hypogammaglobulinemia is a congenital / non acquired form of hypogammaglobulinaemia and can be of heterogeneous etiology.
The condition is characterized by low levels of serum immunoglobulins and impaired antibody responses.
The majority of cases of primary hypogammaglobulinemia are re...
The primary immunodeficiency states are a heterogenous group of disorders that occur when there is an impairment of humoral or cell-mediated immunity in the absence of any recognized precipitating cause such as drug therapy or infective agent such as human immunodeficiency virus (HIV).
Primary mediastinal large B-cell lymphoma is a distinct entity, recognized in the WHO classification of lymphoma.
Primary mediastinal large B-cell lymphoma accounts approximately 5% of large B-cell lymphoma, which is usually disseminated or found in the abdomen. There appears to b...
Primary myelofibrosis is a myeloproliferative neoplasm in which there is the replacement of bone marrow with collagenous connective tissue and progressive fibrosis. It is characterized by:
variable change in the number of granulocy...
Primary ovarian lymphoma (POL) refers to involvement of the ovary with lymphoma but without the involvement of any other site. It is an extremely rare yet well-recognized condition.
POL accounts for ~1.5% of ovarian tumors 5.
The rarity of this condition is probably in...
Primary pleural lymphoma is extremely rare, especially in immunocompetent patients.
Primary pleural lymphoma accounts for <0.5% of all non-Hodgkin lymphoma 2 and ~2.5% of primary chest wall tumors 4.
Primary pleural lymphoma may be Hodgkin or non-Hodgkin lymphoma with...
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...
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.
The prevalence of protein C deficiency in the general population is around 1 per ...
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).
Protein S deficiency may be expected in ≈1 of every 500 people 3.
The spectrum ...
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.
The prevalence of pulmo...
Pulmonary lymphoma refers to lung parenchymal involvement with lymphoma.
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...
Pulmonary Pneumocystis jiroveci infection, also known as Pneumocystis jiroveci pneumonia (PJP) or Pneumocystis pneumonia (PCP), is an atypical pulmonary infection and the most common opportunistic infection in patients with acquired immunodeficiency syndrome (AIDS).
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. If the body temperature is greater than 41.5°C - a rare phenomenon - it i...
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...
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...
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:
surrounding soft tissue edema
Doppler examination is particularly u...
Red blood cells (RBCs), also known as erythrocytes, are cells that carry oxygen by means of hemoglobin, and form part of the cellular component of blood as it circulates throughout the body. These extremely common cells are typically made in the bone marrow in a process called erythropoiesis. Du...
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.
Renal lymphoma is usually a part component of multi-systemic lymphoma. Primary renal lymphoma, which is defined as lymphoma involving the kidney exclusively without any manifestation of extra-renal lymphatic disease 3-5. Typical imaging findings are multiple bilateral hypodense or infiltrative r...
The reticuloendothelial system (RES) comprises a number of tissues:
liver Kupffer cells
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...
Rheumatoid arthritis (RA) is a chronic autoimmune multisystemic inflammatory disease that affects many organs but predominantly attacks the synovial tissues and joints.
The overall prevalence is 0.5-1% and the disease is 2-3 times more common in women 1.
Onset is generally in adu...
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...
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.
The disease predominantly occurs in young adults with a mean age at pre...
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.
Sclerosing angiomatoid nodular transformation (SANT) of the spleen is a recently recognized, rare, non-neoplastic vascular splenic lesion of uncertain etiology.
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...
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 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...
Sézary syndrome (SS) is a type of primary cutaneous T-cell lymphoma.
It is clinically characterized by an extensive erythematous rash covering most of the body as well as the presence of malignant lymphocytes in the blood.
History and etymology
It is named after Albert...
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...
Abdominal manifestations of sickle cell disease (SCD) are wide and can involve many organs.
For a general discussion, please refer to sickle cell disease.
may occur transiently with the sequestration syndrome, where rapid pooling of blood occurs in the spleen, resulting ...
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...
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.
Symptoms and signs reflec...
Sinusoidal obstruction syndrome (SOS), previously known as hepatic veno-occlusive disease (VOD), is a condition arising from occlusion of hepatic venules.
right upper quadrant pain
abnormal liver function tests
Toxic injury to l...
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 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.
Smoldering multiple myeloma is a premalignant stage between monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma.
Similar to MGUS patients, smoldering multiple myeloma patients are asymptomatic.
The criteria for smoldering m...
Solitary plasmacytoma with minimal bone marrow involvement refers to a type of plasmacytoma with bone marrow cytology positive for monoclonal plasma cell infiltration.
In order to fulfill the International Myeloma Working Group criteria for the diagnosis of solitary plasmacytoma with ...
The spleen is an organ of the hematological system and has a role in immune response, storage of red blood cells and hematopoiesis.
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...
Splenic artery aneurysms 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 ps...
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...
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...
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.
Splenic granulomatous disease refers to sequelae arising from granulomatous infection-inflammation of the spleen.
They are a result of:
In latent s...
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.
The recently-described sclerosing angiomatoid nodular transformatio...
Splenic histoplasmosis can manifest with splenomegaly and splenic hypoattenuation. It is more common in immunosuppressed patients (e.g. HIV/AIDS), particularly in endemic areas (e.g. central USA) 1,2. Healed splenic histoplasmosis is one of the causes of diffuse splenic calcifications 2.
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 ...
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:
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.
In blunt trauma, the spleen can account for up to 49% of abdominal organ injuries 2.
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...
Splenunculi, also known as supernumerary spleens, accessory spleens, or splenules, are small nodules of spleen that are separate from the rest of the organ.
They are common, seen in up to 16% of CTs of the abdomen and up to 30% of autopsies 2.
Accessory spleens are 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 predom...
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...
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 Tc-99m constitutes a co-ordination complex in which ligands bond to a central atom of Tc-99m by co-ordinate covalent bonds 4 .
The radioactive te...
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 ...
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...
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...
Thrombotic thrombocytopenic purpura (TTP) is a rare but life-threatening condition characterized by thrombocytopenia, microangiopathic hemolytic anemia and end-organ damage.
The prevalence of TTP is ten cases per one million people 2. Ninety-percent of cases occur in adulthood and...
Thymic rebound hyperplasia is considered a from of true thymic hyperplasia.
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 ...
Tower vertebrae a rare manifestation of sickle cell disease, in which short infarcted vertebrae are seen adjacent to other abnormally grown in height vertebrae.
codfish or h-shaped vertebrae
anterior vertebral vascular notches
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.
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),...
Tumor lysis syndrome (TLS) is situlation representing a constellation of laboratory and clinical derangements inclusive of
It is considered an oncological emergency can occur following treatment of malignancies with high cellul...
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)
Twin anemia polycythemia sequence (TAPS) is considered a variant of the twin to twin transfusion syndrome (TTTS).
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.
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, appendix or terminal ileum.
Typhlitis was first described in children with leukemia and severe neu...
The typical clinical manifestations of multiple myeloma can be recalled using the mnemonic:
R: renal failure
B: bone disease
The CRAB mnemonic can help differentiate multiple myeloma from its precursor diseases - monoclonal gammopathy of undetermin...
Uterine lymphoma refers to involvement of the uterus with lymphoma. Some authors also place lymphoma of the uterine cervix under this group.
It is rare condition with initial uterine involvement occurring in only 1% of patients with lymphoma 3. However, uterine involvement is more...
Vaginal lymphoma can refer to:
secondary involvement of the vagina (secondary vaginal lymphoma) from widespread generalized lymphoma
usually comprises of diffuse large cell B non-Hodgkin's lymphoma (DLBCL) 2
primary vaginal lymphoma
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.
codfish or h-shaped vertebrae
Vitamin B12 deficiency, also known as hypovitaminosis B12 or hypocobalaminemia, is not uncommon, with potentially serious sequelae if not adequately treated.
Vitamin B12 deficiency results in a reduction of two metabolic pathways 3:
conversion of L-methylmalonyl coenzym...
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. ...
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...
Von Willebrand disease (vWD) is the commonest inherited bleeding diathesis but may be acquired.
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...
Waldenström macroglobulinemia, also known as lymphoplasmacytic lymphoma (LPL), is a type of B-cell lymphoma.
Recent publications classify Waldenström macroglobulinemia as a lymphoplasmacytic lymphoma with any level of an IgM paraprotein 10. Therefore the two entities are not synon...
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, ...
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 are divided into granular and non-granular types.
Types of white blood cell:
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...
Widening of the diploic space refers to expansion of the cancellous (spongy) 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 commo...
Wiskott-Aldrich syndrome (WAS) is a rare immunodeficiency disease.
The incidence currently quoted is approximately 4 per million live male births, although there can be regional variation. Rarely occurs in females.
It has a characteristic phenotype that inc...
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.