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.

639 results found
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Facial colliculus syndrome

Facial colliculus syndrome refers to a constellation of neurological signs due to a lesion at the facial colliculus, involving: abducens nerve (CN VI) nucleus facial nerve (CN VII) fibers at the genu medial longitudinal fasciculus Clinical presentation lower motor neuron facial nerve palsy ...
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Fahr syndrome

Fahr syndrome, also known as bilateral striatopallidodentate calcinosis, is characterized by abnormal vascular calcium deposition, particularly in the basal ganglia, cerebellar dentate nuclei, and white matter, with subsequent atrophy. It can be either primary (usually autosomal dominant) or se...
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Failed back syndrome

Failed back syndrome refers to persistent leg and/or lumbar back pain after a surgical procedure. The pathophysiology of this syndrome is complex, as often the operation was technically successful.  Terminology Other names for failed back syndrome include failed back surgery syndrome, post-lam...
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Familial adenomatous polyposis syndrome

Familial adenomatous polyposis syndrome (FAPS) is characterized by the presence of hundreds of adenomatous polyps in the colon. It is the most common of the polyposis syndromes. Terminology Familial polyposis coli, attenuated familial adenomatous polyposis and Gardner syndrome are all variants...
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Familial atypical multiple mole melanoma syndrome

Familial atypical multiple mole melanoma (FAMMM) syndrome is an autosomal dominant genodermatosis characterized by multiple melanocytic nevi (often more than 50) and a family history of melanoma. Pathology Genetics It is associated with mutations in the CDKN2A gene and shows reduced penetranc...
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Familial multiple cavernous malformation syndrome

The familial multiple cavernous malformation syndrome, or familial cerebral cavernous malformation syndrome, is uncommon, accounting for only a minority of cavernous malformations. Epidemiology It has been more frequently reported in patients of Hispanic descent 1. Clinical presentation The ...
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Familial multiple lipomatosis

Familial multiple lipomatosis (FML) is a hereditary syndrome of multiple encapsulated lipomas which are found on the trunk and extremities, with relative sparing of the head and shoulders.  Terminology It is clinically distinct from the similarly named multiple symmetric lipomatosis with which...
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Fatco syndrome

Fatco syndrome is a syndrome consisting of fibular aplasia tibial campomelia and oligosyndactyly. It is a syndrome of unknown genetic basis and inheritance with variable expressivity and penetrance. Differential diagnosis Fuhrmann syndrome and Al-Awadi syndrome are said to be similar to FA...
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Fat embolism syndrome

Fat embolism syndrome (FES) is a rare clinical condition caused by circulating fat emboli leading to a multisystemic dysfunction. The classical clinical triad consists of: respiratory distress cerebral abnormalities petechial hemorrhages Epidemiology It occurs in ~2.5% (range 0.5-4%) of tho...
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Fat pad impingement syndromes of the knee

In fat-pad impingement syndromes, the etiologies are different for each knee fat pad. In anterior suprapatellar fat pad impingement syndrome, the cause is usually due to either a developmental cause related to the anatomy of the extensor mechanism or may be related to abnormal mechanics. In thi...
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Febrile infection-related epilepsy syndrome (FIRES)

Febrile infection-related epilepsy syndrome (FIRES) is a severe postinfectious neurological disorder that presents with status epilepticus in a previously normal child (or less commonly adult) after a febrile illness. In these cases, pleocytosis or elevated protein levels on CSF has been report...
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Felty syndrome

Felty syndrome is a rare hematological syndrome in rheumatoid arthritis. Epidemiology It is thought to occur in ~ 1% of patients with rheumatoid arthritis 2. Clinical presentation Felty syndrome comprises of the triad of: rheumatoid arthritis ​typically with severe articular and extra-arti...
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Femoral facial syndrome

Femoral facial syndrome, also known as femoral hypoplasia-unusual facies syndrome, is a rare congenital syndrome characterized by varying degrees of femoral hypoplasia and facial dysmorphism 1. Clinical presentation Femoral facial syndrome can cause varying degrees of femoral malformation rang...
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Fetal head sparing theory

The fetal head sparing theory is one that underpins asymmetrical intra-uterine growth restriction, where the difference between normal head circumference and decreased abdominal circumference is attributed to the fetus's ability to preferentially supply the cerebral, coronary, adrenal and spleni...
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Fitz-Hugh-Curtis syndrome

Fitz-Hugh-Curtis syndrome (FHCS), or perihepatitis, is the inflammation of the liver capsule and overlying pertioneum associated with adhesion formation without the involvement of the hepatic parenchyma. It is a chronic complication of pelvic inflammatory disease (PID). Epidemiology The preval...
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Flat back syndrome

Flat back syndrome (FBS) refers to the decrease or absence of the normal lumbar lordosis resulting primarily in chronic lumbar pain. Terminology  Flat back syndrome is a different condition from straight back syndrome and the two should not be confused or conflated. Clinical presentation Mos...
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Focal dermal hypoplasia syndrome

Focal dermal hypoplasia syndrome, is also known as Goltz syndrome, and is not to be confused with the similar-sounding Gorlin-Goltz syndrome. Epidemiology A rare disorder that follows an X-linked dominant inheritance pattern. More commonly seen in males than females. Worldwide only 200-300 cas...
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Foster Kennedy syndrome

Foster Kennedy syndrome describes the clinical syndrome of unilateral optic atrophy with contralateral papilledema caused by an ipsilateral compressive mass lesion. Clinical presentation The syndrome consists of two cardinal features 1,2: ipsilateral optic nerve atrophy presenting with centra...
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Fowler syndrome

Fowler syndrome, also known as proliferative vasculopathy and hydranencephaly-hydrocephaly syndrome (PVHH), is a rare inherited condition. Terminology Not to be confused with Fowler syndrome of urinary retention, a condition caused by primary failure of urethral sphincter relaxation resulting ...
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F P Weber syndrome

F P Weber syndrome (FPWS) is a traditional eponymous denomination of a certain type of angiodysplasia, that would nowadays rather be called a mixed hemolymphatic congenital vascular malformation (CVM) with arteriovenous (AV) shunting, based on the Hamburg classification of CVMs. In his original...
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Fraser syndrome

Fraser syndrome is an extremely rare congenital syndromic anomaly.  Epidemiology The estimated incidence is at around 0.04:10,000 live-born infants and 1:10,000 stillbirths. Clinical spectrum The syndromic spectrum can comprise of: cryptophthalmos syndactyly: often cutaneous tracheal atre...
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Freeman Sheldon syndrome

Freeman Sheldon syndrome (FSS), also known as distal arthrogryposis type IIa, is a congenital condition where multiple joint contractures are a key feature. Affected individuals are known to have a characteristic facial expression resembling that of a whistling face and hence the syndrome is als...
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Frey syndrome

Frey syndrome (also known as Baillarger syndrome, Dupuy syndrome, and auriculotemporal syndrome) is a complication of parotid surgery. It clinically manifests as sweating and reddening in the region of the face supplied by the auriculotemporal nerve. The symptoms typically occur when tasting foo...
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Frontonasal dysplasia

Frontonasal dysplasia, also known as median cleft face syndrome, is a rare disorder characterized by midline defects involving the face, head, and central nervous system. Epidemiology Frontonasal dysplasia is considered to be a very rare condition, with approximately 100 cases having been repo...
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Functional gastrointestinal disorders

The functional gastrointestinal disorders (FGIDs) are a set of conditions characterized by their chronic GI manifestations, in the absence of structural abnormality of the gut. These conditions are common and may be disabling in nature. The understanding of their pathogenesis is incomplete, comp...
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Galloway-Mowat syndrome

Galloway-Mowat syndrome (GAMOS) is a rare autosomal recessive disorder characterized by nephrotic syndrome and central nervous system (CNS) abnormalities, namely microcephaly. Epidemiology Galloway-Mowat syndrome is considered extremely rare. Approximately 40 cases have been reported worldwide...
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Gasperini syndrome

Gasperini syndrome is a rare pontine stroke syndrome that involves the caudal pontine tegmentum. Clinical presentation Classically, the syndrome presents with 1-3: involvement of the CN V nucleus (sensory nucleus of the trigeminal nerve): ipsilateral facial sensory loss involvement of the CN...
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GATA2 deficiency

GATA2 deficiency is a germ-line disease expressed as a wide spectrum of phenotypes, including monocytopenia, myelodysplasia, myeloid leukaemias, and lymphedema. It is a rare cause of pulmonary alveolar proteinosis. Clinical presentation GATA2 deficiency has considerably variable clinical manif...
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Gerstmann-Straussler-Scheinker disease

Gerstmann-Straussler-Scheinker disease is a very rare type of human transmissible spongiform encephalopathy. It manifests with dementia and/or ataxia and is due to a mutation in the prion protein (PRNP) gene, which is inherited in an autosomal dominant pattern.  History and etymology It is nam...
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Gerstmann syndrome

Gerstmann syndrome, also known as angular gyrus syndrome, is a dominant hemisphere stroke syndrome affecting the left parietal lobe in the region of the angular gyrus, consisting of four components:  agraphia or dysgraphia acalculia or dyscalculia finger agnosia left-right disorientation Pu...
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Giant axonal neuropathy

Giant axonal neuropathy is a rare, autosomal recessive neurodegenerative disease of both the peripheral nervous system (PNS) and the central nervous system (CNS). It is one of the inherited leukodystrophies.  Epidemiology Approximately 50 affected families have been reported in the literature;...
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Gillespie syndrome

Gillespie syndrome is a rare genetic condition presenting as a mydriasis, secondary to an omnipresent partial aniridia. The abnormal iris is bilateral, with a highly-specific scalloped inner margin, due to hypoplasia of the central constrictor pupillae fibers. Associated features include an unch...
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Glycogen storage disease

Glycogen storage disease (GSD) refers to a number of syndromes which are characterized by a defect in synthesis, metabolism or storage of glycogen. Pathology There are many types of GSD: type I: von Gierke disease type II: Pompe disease type III: Cori or Forbes disease type IV: Andersen di...
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Glycogen storage disease type I

Glycogen storage disease type I (GSD-I), also known as von Gierke disease, is a type of glycogen storage disease where there is excess deposition of glycogen primarily in the liver, but also in the kidney and small bowel. Epidemiology It occurs approximately one in every 100,000 live births 2,...
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Goldenhar syndrome

Goldenhar syndrome, also known as oculo-auriculo-vertebral spectrum (OAVS), Goldenhar-Gorlin syndrome or facio-auriculo-vertebral dysplasia, is a complex congenital anomaly characterized by abnormalities of the ears, eyes and vertebrae. Epidemiology The estimated incidence is at 1 in 3000-5000...
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Gomez-Lopez-Hernandez syndrome

Gomez-Lopez-Hernandez syndrome, also known as cerebellotrigeminal-dermal dysplasia, is a rare phakomatosis characterized by rhombencephalosynapsis, parietal-occipital scalp alopecia, brachycephaly, facial malformations and trigeminal anesthesia.  History and etymology It is named after Manuel ...
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Goodman syndrome

Goodman syndrome is a type of acrocephalopolysyndactyly (often considered type IV). It is an extremely rare genetic disorder characterized by marked malformations of the head and face, abnormalities of the hands and feet, and congenital heart disease. The syndrome is inherited as an autosomal re...
Article

Goodpasture syndrome

Goodpasture syndrome, also referred as antiglomerular basement membrane (anti-GBM) antibody disease, is an autoimmune disease characterized by damage to the alveolar and renal glomerular basement membranes by a cytotoxic antibody. It is a type of pulmonary-renal syndrome. Goodpasture syndrome i...
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Good syndrome

Good syndrome is a rare paraneoplastic syndrome in which a thymoma causes hypogammaglobulinemia and humoral immunodeficiency. It has been estimated to occur in 0.2%–2% of thymomas 2. thymoma low to absent B-cells T-cell mediated defects CD4 T-cell lymphopenia inverted CD4/CD8+ T-cell ratio ...
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Gradenigo syndrome

Gradenigo syndrome consists of the triad of: petrous apicitis abducens nerve palsy, secondary to involvement of the nerve as it passes through Dorello canal retro-orbital pain, or pain in the cutaneous distribution of the frontal and maxillary divisions of the trigeminal nerve, due to extensi...
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Greig cephalopolysyndactyly syndrome

The Greig cephalopolysyndactyly syndrome (GCPS) is a rare pleiotropic, multiple congenital anomaly syndrome. It is primarily characterized by: polydactyly-polysyndactyly: preaxial polydactyly (most common 2) or mixed pre- and postaxial polydactyly true ocular hypertelorism macrocephaly fro...
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Grisel syndrome

Grisel syndrome is a rare cause of torticollis that involves subluxation of atlanto-axial joint from inflammatory ligamentous laxity following an infectious process in the head and neck, usually a retropharyngeal abscess. Epidemiology It usually occurs in infants or young children. Clinical p...
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Guillain-Barré syndrome

Guillain-Barré syndrome (GBS) is a heterogeneous group of autoimmune polyradiculopathies, involving sensory, motor, and autonomic nerves. It is the most common cause of rapidly progressive flaccid paralysis. It is believed to be one of a number of related conditions, sharing a similar underlying...
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Gullo syndrome

Gullo syndrome, also known as benign pancreatic hyperenzymemia, is characterized by the abnormal elevation of the serum levels of most or all of the pancreatic enzymes without any evidence of underlying pancreatic pathology. It is a diagnosis of exclusion made when all other laboratory assays an...
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Hemoglobinopathies

A hemoglobinopathy is a genetic disorder which alters the structure of hemoglobin 1. The result is reduced oxygen-carrying capacity of the blood to the tissues, and other sequelae. Clinical presentation Clinical presentation varies, is related to hypoxia, and characteristically includes the fo...
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Hemolytic uremic syndrome

Hemolytic uremic syndrome (HUS) is a multisystem thrombotic microangiopathic disease characterized by the triad of renal failure, hemolytic anemia and thrombocytopenia. It is the most common cause of renal failure in infancy and childhood requiring dialysis.  There are two forms of this syndrom...
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Hemophagocytic lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) is a non-malignant but often-fatal disorder of immune dysregulation affecting multiple organs. It is also known as macrophage activation syndrome when occurring in the setting of a rheumatologic disorder. Epidemiology It typically affects infants and yo...
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Haglund syndrome

Haglund syndrome refers to the triad (Haglund triad) of: insertional Achilles tendinopathy retrocalcaneal bursitis Haglund deformity (i.e. posterosuperior calcaneal exostosis) Terminology Haglund syndrome is a painful condition of the heel and its diagnosis requires a combination with clini...
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Hajdu-Cheney syndrome

Hajdu-Cheney syndrome is a very rare connective tissue disorder with only 50 cases reported in the literature 7. Clinical presentation It is mostly diagnosed in adulthood or adolescence with the presence of a positive family history. There has been no link between severity of disease and age o...
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Hamatolunate impingement syndrome

Hamatolunate impingement is an uncommon cause of ulnar-sided wrist pain. The condition occurs most commonly in wrists where there is type II lunate morphology (existence of a medial facet on the distal lunate for articulation with the hamate). Repeated impaction of the opposing articular surface...
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Hamman syndrome

Hamman syndrome, also known as Macklin syndrome, refers to spontaneous pneumomediastinum along with subcutaneous emphysema. Epidemiology It is a rare entity most often encountered in young adults. It is a known entity peri- and postpartum 3. Clinical presentation The condition is most common...
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Hand-foot syndrome (chemotherapy)

Hand-foot syndrome, also known as palmar-plantar erythrodysaesthesia or Burgdorf reaction, is a benign, aseptic, self-limiting complication of many chemotherapeutic agents characterized by a widespread erythema, edema and ulceration of the hands and feet.  Causative drugs Many chemotherapeutic...
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Heerfordt syndrome

Heerfordt syndrome, also known as Heerfordt-Waldenström syndrome or uveoparotid fever, is a variant of sarcoidosis, comprising of: fever parotid enlargement facial palsy ocular involvement (anterior uveitis) Epidemiology The exact prevalence is unknown, as only isolated case reports exist....
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Heiner syndrome

The Heiner syndrome is a rare form of primary pulmonary hemosiderosis associated with an allergy to cow's milk. The syndrome includes: rectal blood loss with hypochromic microcytic anemia pulmonary infiltrates (often recurrent) hypoproteinemia See also pulmonary hemosiderosis
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HELLP syndrome

HELLP syndrome is a pregnancy-related condition and is an abbreviation for: haemolysis elevated liver enzymes and  low platelets It is considered a severe and life-threatening form of pre-eclampsia although it can occur without co-existing pre-eclampsia.  Epidemiology The estimated inciden...
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Hemiconvulsion-hemiplegia epilepsy syndrome

Hemiconvulsion-hemiplegia epilepsy syndrome (HHE) is a clinical syndrome of infancy or early childhood that is associated with seizures, cerebral hemiatrophy and transient or permanent epilepsy. It refers to the characteristic holohemispheric global atrophy of one hemisphere, that is independen...
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Hemifacial microsomia

Hemifacial microsomia (HFM) is the second most common congenital facial anomaly after cleft lip/palate. The condition may vary from mild to severe. Goldenhar syndrome has been described as a variant of HFM, in which vertebral anomalies and epibulbar dermoids were present. Terminology HFM is al...
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Hemihyperplasia

Hemihyperplasia, also known as hemihypertrophy, is asymmetry in size between the right and left of the body, more than can be attributed to normal variation. Terminology Hemihyperplasia is more scientifically correct than hemihypertrophy as the cells are hyperplastic rather than hypertrophied ...
Article

Hemimedullary syndrome

Hemimedullary syndrome, also known as Reinhold syndrome, occurs as a result of the occlusion of the ipsilateral vertebral artery proximal to the posterior inferior cerebellar artery and its anterior spinal artery branches 1-3. This situation causes lateral medullary infarct and medial medullary ...
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Hepatopulmonary syndrome

Hepatopulmonary syndrome (HPS) is a clinical syndrome defined by the presence of the following: liver disease dilation of pulmonary vasculature may involve pulmonary capillaries, pulmonary arteriovenous malformations, or pleural AVMs abnormalities in oxygenation elevation in the alveolar-ar...
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Hepatorenal syndrome

Hepatorenal syndrome refers to a form of acute kidney injury caused by changes in renal blood flow regulation due to liver pathology 1. Although the syndrome occurs mainly in cirrhotic livers it has been reported in patients with acute fulminant liver failure as well 1. Epidemiology The incide...
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Hereditary angiopathy with nephropathy, aneurysms, and muscle cramps syndrome

Hereditary angiopathy with nephropathy, aneurysms, and muscle cramps (HANAC) syndrome is an autosomal dominant monogenic COL4A1-related disorder. Epidemiology The exact prevalence is unknown. Clinical presentation The cardinal features of HANAC syndrome are helpfully described in the name of...
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Hereditary breast and ovarian cancer syndrome

Hereditary breast and ovarian cancer (HBOC) syndrome is caused by a mutation to either BRCA1 or BRCA2 genes. These patients have an increased risk of breast cancer, ovarian cancer, pancreatic cancer and prostate cancer. However, these gene mutations are not the only cause of hereditary breast ca...
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Hereditary hemorrhagic telangiectasia

Hereditary hemorrhagic telangiectasia (HHT), also known as Osler-Weber-Rendu syndrome, is a rare inherited disorder characterized by abnormal blood vessel formation in the skin, mucous membranes, and organs including the lungs, liver, and central nervous system. Epidemiology Worldwide prevalen...
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Hereditary multiple exostoses

Hereditary multiple exostoses, also known as diaphyseal aclasis or osteochondromatosis is an autosomal dominant condition, characterized by the development of multiple osteochondromas. Epidemiology Hereditary multiple exostoses demonstrate an autosomal dominant inheritance pattern, with incomp...
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Hereditary non-polyposis colorectal cancer

Hereditary non-polyposis colorectal cancer (HNPCC), also known as Lynch syndrome, is an autosomal dominant condition which predisposes to a host of malignancies, including colorectal carcinoma. It is considered the most frequent form of hereditary colorectal cancer. Diagnosis requires evaluation...
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Hereditary renal cancer syndromes

Despite the vast majority of renal cancers being sporadic, there are a number of hereditary renal cancer syndromes: von Hippel Lindau syndrome: predominantly clear cell type tuberous sclerosis: predominantly clear cell type (also associated with angiomyolipoma) hereditary paraganglioma-pheoch...
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Herlyn-Werner-Wunderlich syndrome

Herlyn-Werner-Wunderlich (HWW) syndrome, is a rare anomaly characterized by Müllerian duct anomalies (MDA) associated with mesonephric duct anomalies 3. This entity is also known as obstructed hemivagina and ipsilateral renal anomaly (OHVIRA). It is not to be confused with the Wunderlich syndrom...
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Hermansky-Pudlak syndrome

Hermansky-Pudlak syndrome (HPS) is a rare syndrome which consists of: oculocutaneous hypopigmentation (albinism) platelet dysfunction  abnormal storage of autofluorescent pigment (ceroid or lipofuscin)  typically occurs within lysosomal organelles of the cells of multiple organs and the reti...
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Heterotaxy syndrome

Heterotaxy syndrome or situs ambiguus (also commonly, but etymologically less correctly, spelled situs ambiguous) is a disturbance in the usual left-right distribution of the thoracic and abdominal organs that does not entirely correspond to the complete mirror image (situs inversus). It occurs...
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Heyde syndrome

Heyde syndrome is an association between aortic valve stenosis and gastrointestinal hemorrhage. The etiology of the gastrointestinal bleeding in this setting is uncertain, but it is thought to be related to intestinal angiodysplasia. The strength of this association independent of age-related d...
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HIV-associated nephropathy

HIV-associated nephropathy (HIVAN) is commonly seen in patients with HIV/AIDS and leads to end-stage renal disease (ESRD). The diagnosis is not imaging-based and must be confirmed by renal biopsy. Epidemiology HIVAN is seen in patients at advanced stages of HIV and AIDS, but it can also be see...
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Horizontal gaze palsy with progressive scoliosis

Horizontal gaze palsy with progressive scoliosis (HGPPS) is a rare autosomal recessive disease. Clinical presentation Abnormal horizontal gaze while normal vertical gaze and kyphoscoliosis. Horizontal gaze requires the action of ipsilateral abducent nerve and contralateral oculomotor nerve and...
Article

Hughes-Stovin syndrome

Hughes-Stovin syndrome (HSS) is a vasculitis that predominantly affects large vessels. The disease bears some resemblance to Behçet disease. Epidemiology Hughes-Stovin syndrome is very rare 7. It occurs predominantly between the 2nd to 4th decades. There is a recognized male predilection.  Cl...
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Hunter syndrome

Hunter syndrome, also known as mucopolysaccharidosis type II (MPS II) is a rare genetic mucopolysaccharidosis disorder characterized by specific clinical features 1. Epidemiology Hunter syndrome is an X-linked recessive disease and therefore much more common in males. It is a rare disorder wit...
Article

Hurler syndrome

Hurler syndrome is one of the mucopolysaccharidoses (MPS type I). Epidemiology The estimated incidence is ~1:100,000. Clinical presentation It manifests in the first years of life with intellectual disability, corneal clouding, deafness, and cardiac disease. Death usually occurs within the f...
Article

Hutchinson syndrome

Hutchinson syndrome is a seldom-used term to denote a syndromic presentation of children with skeletal metastases from neuroblastoma. Terminology Unfortunately, there is a lack of consensus in the definition with two descriptions most commonly encountered in the literature: limping and irrita...
Article

Hydrolethalus syndrome

Hydrolethalus syndrome is a rare lethal genetic syndrome characterized by multiple developmental defects of fetus which include  midline malformations cleft lip + / - palate CNS malformations fetal hydrocephalus agenesis of the corpus callosum Dandy-Walker malformation absent midline stru...
Article

Hyperimmunoglobulin IgE syndrome

Hyperimmunoglobulin E (hyper IgE) syndrome (HIES), also known as Job syndrome, consists of a heterogeneous group of complex hereditary combined B- and T-cell immune deficiency diseases characterized by recurrent Staphylococcus aureus chest infections, characteristic coarse facial appearance and ...
Article

Hyperparathyroidism-jaw tumor syndrome

Hyperparathyroidism-jaw tumor syndrome is an extremely rare condition where a gene mutation results in hyperparathyroidism in association with both benign and malignant tumors, most notably, tumors in the mandible or maxilla 2. Epidemiology Approximately 200 cases have been reported in the med...
Article

Hypomelanosis of Ito

Hypomelanosis of Ito, also known as incontinentia pigmenti achromians, is the third most frequent phakomatosis, involving a wide spectrum of defects in multiple organ systems. Epidemiology The prevalence is unknown, being reported as between 1 per 8000 patients in a general pediatric hospital ...
Article

Hypophosphatasia

Hypophosphatasia refers to a rare metabolic disorder characterized by deficient serum alkaline phosphatase activity. The effects of hypophosphatasia are primarily seen in the skeletal system. The condition has marked variation in clinical expression (see subtypes). Epidemiology The true incide...
Article

Hypoplastic left heart syndrome

Hypoplastic left heart syndrome (HLHS) is a cyanotic congenital cardiac anomaly where affected individuals can have profound cyanosis and cardiac failure. It is one of the commonest causes for a neonate to present with congestive cardiac failure and the 4th most frequent cardiac anomaly to mani...
Article

Hypothenar hammer syndrome

Hypothenar hammer syndrome occurs from trauma to the distal ulnar artery or proximal portion of superficial palmar arch as a result of repetitive trauma to the hypothenar eminence. Originally described in patients using hammers and screwdrivers, it is also seen in various athletes such as basket...
Article

Idiopathic pneumonia syndrome

Idiopathic pneumonia syndrome (IPS) refers to diffuse lung injury which can occur following haematopeotic stem cell transplantation where neither an infectious nor non-infectious etiology can be found. Epidemiology The incidence of IPS is thought to be around 12% following haematopoetic stem c...
Article

Idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a clinical syndrome and considered the most common and the most lethal form of pulmonary fibrosis corresponding to the histologic and imaging pattern of usual interstitial pneumonia. It is more common in elderly men and diagnosed by:  histological or imagi...
Article

Idiopathic retroperitoneal fibrosis

Idiopathic retroperitoneal fibrosis, also known as Ormond disease or occasionally Albarran-Ormond syndrome 6, is a subtype of retroperitoneal fibrosis where no cause is found. It includes a spectrum of diseases which are characterized by fibroinflammatory tissue encasing the abdominal aorta and ...
Article

Iliotibial band syndrome

Iliotibial band (friction) syndrome is a common cause of lateral knee pain related to intense physical activity resulting in chronic inflammation. Alternatively, the same pathology can occur over the greater trochanter and is considered the same diagnosis. Epidemiology Commonly affect young pa...
Article

Immune reconstitution inflammatory syndrome

Immune reconstitution inflammatory syndrome (IRIS) is paradoxical deterioration of a pre-existing illness following abrupt improvement in an individual's immune function. It is classically seen in HIV/AIDS patients following initiation of highly active antiretroviral therapy (HAART). Increasingl...
Article

Impingement syndrome

Impingement syndrome is a painful encroachment of joint motion caused by protruding bony or soft tissue structures. Epidemiology Impingement syndromes are common and can occur at any age. Risk factors developmental osseous anomalies overuse activity trauma Associations osteoarthritis te...
Article

Incontinentia pigmenti

Incontinentia pigmenti, also known as Bloch-Sulzberger syndrome, is a rare condition that can affect many body systems, especially the skin. As an X-linked dominant genetic disorder, it occurs much more often in females than in males. Epidemiology Incontinentia pigmenti is rare and the true pr...
Article

Inferior medial pontine syndrome

Inferior medial pontine syndrome, also known as Foville syndrome, is one of the brainstem stroke syndromes occurring when there is infarction of the medial inferior aspect of the pons due to occlusion of the paramedian branches of the basilar artery 1-3. This infarction involves the following 1-...
Article

Internuclear ophthalmoplegia

Internuclear ophthalmoplegia (INO) describes a clinical syndrome of impaired adduction in one eye with dissociated horizontal nystagmus of the other abducting eye, due to a lesion in the medial longitudinal fasciculus (MLF) ipsilateral to the eye unable to adduct. It is a common finding in multi...

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