Miscellaneous Conditions and Syndromes A–Z
Concise, high-yield descriptions of named syndromes, unusual presentations and less common diseases. These are short summaries rather than full guidelines; follow the links to the appropriate chapter for context.
A
Alport syndrome
What it is: Inherited type IV collagen disorder causing progressive glomerular disease, sensorineural hearing loss and characteristic ocular abnormalities. X-linked COL4A5 disease is common, but autosomal forms occur.
Recognition: Persistent microscopic haematuria, a family history of renal impairment or hearing loss, and occasionally anterior lenticonus.
Investigations and management: Check urine ACR, renal function and hearing; confirm with appropriate genetic assessment. Renin–angiotensin system blockade can delay progression.
Antiphospholipid syndrome
What it is: Autoimmune thrombophilia associated with venous or arterial thrombosis and certain pregnancy complications. Diagnosis requires a compatible clinical event plus persistent laboratory antiphospholipid antibodies.
Recognition: Recurrent thrombosis, unusual-site thrombosis or characteristic obstetric morbidity; do not diagnose from one positive antibody result.
Investigations and management: Confirm antibodies on two occasions at least 12 weeks apart and individualise anticoagulation; direct oral anticoagulants are generally avoided in high-risk triple-positive APS.
Artery of Percheron infarction
What it is: A rare vascular variant in which one perforating branch of a posterior cerebral artery supplies both paramedian thalami, sometimes extending to the rostral midbrain. Occlusion produces bilateral paramedian thalamic infarction.
Recognition: Sudden reduced consciousness, memory impairment and vertical gaze palsy; early non-contrast CT may be unrevealing.
Investigations and management: Consider urgent MRI with diffusion-weighted imaging, while maintaining the standard acute stroke pathway and reperfusion eligibility assessment.
B
Behçet disease
What it is: Relapsing, variable-vessel inflammatory disease with oral aphthae, genital ulcers and ocular inflammation. Vascular, neurological and gastrointestinal complications can occur.
Recognition: Recurrent oral and genital ulceration with uveitis or retinal vasculitis.
Investigations and management: Urgent specialist review for visual or neurological symptoms; exclude infections and other mimics before immunosuppression.
Brugada syndrome
What it is: Inherited arrhythmia syndrome associated with characteristic right-precordial ECG changes and risk of ventricular fibrillation, often without structural heart disease.
Recognition: Syncope, nocturnal agonal respirations or sudden cardiac death in relatives; fever may unmask the ECG pattern.
Investigations and management: Arrange inherited cardiac conditions assessment; treat fever promptly and review medicines that may provoke arrhythmias.
C
Carcinoid syndrome
What it is: Systemic effects of serotonin and other mediators released by some neuroendocrine tumours, often after hepatic metastasis or extra-portal drainage.
Recognition: Episodic flushing, secretory diarrhoea, bronchospasm and right-sided valvular lesions.
Investigations and management: Consider 24-hour urinary 5-HIAA or plasma 5-HIAA where appropriate, medication/dietary confounders, and specialist imaging.
Charcot–Marie–Tooth disease
What it is: A heterogeneous group of inherited peripheral neuropathies affecting motor and often sensory axons or myelin.
Recognition: Slowly progressive distal weakness, pes cavus, foot drop and reduced distal reflexes, often with a family history.
Investigations and management: Nerve-conduction studies and targeted genetic testing establish subtype; orthoses, rehabilitation and genetic counselling are central.
D
DiGeorge syndrome (22q11.2 deletion)
What it is: Chromosomal microdeletion syndrome with variable cardiac, immune, palatal and endocrine abnormalities.
Recognition: Conotruncal congenital heart disease, hypocalcaemia, recurrent infections or palatal dysfunction.
Investigations and management: Assess calcium, immune function, heart and developmental needs; confirm using appropriate genomic testing.
Dressler syndrome
What it is: Post-cardiac-injury inflammatory pericarditis, classically developing weeks after myocardial infarction or cardiac surgery.
Recognition: Pleuritic chest pain, fever and sometimes pericardial/pleural effusion following cardiac injury.
Investigations and management: Assess ECG, inflammatory markers and echocardiography, excluding recurrent myocardial ischaemia and other urgent causes.
E
Ehlers–Danlos syndromes
What it is: A group of hereditary connective tissue disorders with variable joint hypermobility, skin features and tissue fragility. Vascular EDS is distinct and may cause arterial or organ rupture.
Recognition: Hypermobility with recurrent injury, unusually fragile skin or a concerning personal/family history of vascular events.
Investigations and management: Subtype assessment determines whether genetic testing, vascular surveillance and specific precautions are needed.
Eisenmenger syndrome
What it is: Pulmonary vascular disease following a longstanding significant systemic-to-pulmonary congenital cardiac shunt, causing shunt reversal or bidirectional flow and cyanosis.
Recognition: Cyanosis and exercise limitation in an adult with congenital heart disease; erythrocytosis may be compensatory.
Investigations and management: Specialist adult congenital cardiac and pulmonary hypertension management is essential; avoid routine phlebotomy.
F
Fabry disease
What it is: X-linked lysosomal storage disorder due to deficient α-galactosidase A activity, causing systemic glycosphingolipid accumulation.
Recognition: Acroparesthesia, angiokeratomas, corneal verticillata, renal disease, unexplained left ventricular hypertrophy or early stroke.
Investigations and management: Confirm with enzyme testing and GLA molecular analysis as appropriate; disease-specific therapies are specialist led.
G
Gilbert syndrome
What it is: Common benign reduction in bilirubin conjugation caused by UGT1A1 variants.
Recognition: Intermittent mild unconjugated hyperbilirubinaemia during fasting, illness or stress, with normal other liver tests and no haemolysis.
Investigations and management: Diagnosis is usually clinical after excluding haemolysis and liver disease; no treatment is required.
Goodpasture disease (anti-GBM disease)
What it is: Autoantibodies against glomerular and sometimes alveolar basement membranes can cause rapidly progressive crescentic glomerulonephritis and pulmonary haemorrhage.
Recognition: Haemoptysis, rapidly worsening renal function and a nephritic urine sediment; lung bleeding may be absent.
Investigations and management: Urgent renal and respiratory assessment with anti-GBM antibodies and appropriate immunosuppressive treatment; this is a medical emergency.
H
Hereditary haemorrhagic telangiectasia
What it is: Autosomal dominant vascular dysplasia, also called Osler–Weber–Rendu syndrome, characterised by telangiectasia and visceral arteriovenous malformations.
Recognition: Repeated spontaneous epistaxis, iron deficiency, characteristic telangiectasia and family history.
Investigations and management: Specialist screening for pulmonary and cerebral AVMs is important because clinically silent lesions may cause serious complications.
Horner syndrome
What it is: Interruption of the sympathetic pathway to the eye and face produces ipsilateral mild ptosis and miosis, sometimes anhidrosis.
Recognition: New painful Horner syndrome with ipsilateral neck or headache is a red flag for carotid artery dissection.
Investigations and management: Urgent vascular imaging when acute or painful; assess for apical lung, brainstem or cervical causes depending on the context.
I
Insulinoma
What it is: Usually a pancreatic neuroendocrine tumour causing endogenous hyperinsulinaemic hypoglycaemia.
Recognition: Whipple triad: symptoms, documented low glucose and relief when glucose is corrected, often during fasting.
Investigations and management: During supervised hypoglycaemia obtain paired glucose, insulin, C-peptide and relevant drug screen before localisation imaging.
J
Jervell and Lange–Nielsen syndrome
What it is: Rare autosomal recessive congenital long-QT syndrome accompanied by bilateral severe sensorineural hearing loss.
Recognition: Congenital deafness with syncope, seizure-like episodes or a family history of sudden cardiac death.
Investigations and management: ECG and inherited-arrhythmia referral are urgent when suspected; evaluate relatives as appropriate.
K
Klinefelter syndrome
What it is: Sex-chromosome aneuploidy, usually 47,XXY, associated with primary testicular failure and variable neurodevelopmental features.
Recognition: Tall stature, small firm testes, gynaecomastia, infertility and raised gonadotrophins.
Investigations and management: Confirm with karyotype; assess testosterone deficiency, bone health and fertility options.
L
Lemierre syndrome
What it is: Septic thrombophlebitis of the internal jugular vein after an oropharyngeal infection, often involving Fusobacterium necrophorum.
Recognition: Sore throat followed by systemic sepsis, unilateral neck pain or swelling and septic pulmonary emboli.
Investigations and management: Urgent blood cultures, appropriate imaging and hospital antibiotics; early recognition prevents delay.
Long QT syndrome
What it is: Inherited or acquired abnormal ventricular repolarisation increasing risk of torsades de pointes and syncope or sudden death.
Recognition: Syncope during exertion, emotion or sudden noise; look for QT-prolonging drugs and electrolyte abnormalities.
Investigations and management: Check QTc, potassium, magnesium, family history and medication list; specialist evaluation is indicated for probable congenital disease.
M
Marfan syndrome
What it is: Autosomal dominant connective tissue disorder, often involving FBN1, with skeletal, ocular and cardiovascular manifestations.
Recognition: Aortic root dilatation, ectopia lentis, long-limbed skeletal phenotype and family history.
Investigations and management: Cardiovascular imaging and genetic/specialist assessment are central because aortic complications determine risk.
Myasthenia gravis
What it is: Autoimmune impairment of neuromuscular junction transmission, usually mediated by antibodies to acetylcholine receptor or MuSK.
Recognition: Fatigable ptosis, diplopia, bulbar weakness and respiratory muscle weakness; sensation remains normal.
Investigations and management: Check neuromuscular antibodies and appropriate neurophysiology; escalating dysphagia or breathlessness needs urgent assessment.
N
Neurofibromatosis type 1
What it is: Autosomal dominant disorder caused by NF1 variants, with characteristic cutaneous signs and variable neurological, ocular and neoplastic complications.
Recognition: Multiple café-au-lait macules, axillary freckling and neurofibromas; presentation depends on age.
Investigations and management: Clinical/genetic assessment and age-appropriate surveillance, including vision and blood pressure, are important.
P
Pancoast tumour
What it is: Superior pulmonary sulcus tumour with possible involvement of lower brachial plexus, sympathetic chain, ribs or vertebrae.
Recognition: Severe shoulder/medial arm pain, hand weakness and sometimes Horner syndrome.
Investigations and management: Urgent chest imaging and specialist cancer assessment are required; a normal initial chest X-ray does not exclude it.
Pseudohypoparathyroidism
What it is: Rare heterogeneous disorders of resistance to parathyroid hormone, often featuring hypocalcaemia and elevated PTH; some subtypes show Albright hereditary osteodystrophy.
Recognition: Hypocalcaemia with raised PTH despite adequate vitamin D and renal function, sometimes with short metacarpals.
Investigations and management: Confirm the biochemical pattern and refer to endocrinology for molecular characterisation and treatment.
R
Ramsay Hunt syndrome
What it is: Herpes zoster oticus with facial nerve involvement due to reactivation of varicella-zoster virus.
Recognition: Painful vesicles around the ear or palate with ipsilateral lower motor neuron facial palsy, sometimes vertigo or hearing loss.
Investigations and management: Early clinical assessment and time-sensitive antiviral treatment are important; protect the cornea if eye closure is impaired.
Reye syndrome
What it is: Rare acute encephalopathy with hepatic mitochondrial dysfunction, classically following a viral illness in children.
Recognition: Vomiting, behavioural change and reduced consciousness with hepatic dysfunction, sometimes after salicylate exposure.
Investigations and management: Urgent hospital management and evaluation for metabolic, infectious and toxic mimics. Aspirin is avoided in under-16s except on specialist advice.
S
Sheehan syndrome
What it is: Postpartum pituitary ischaemic injury following severe obstetric haemorrhage and hypotension.
Recognition: Failure of lactation, amenorrhoea, fatigue, hyponatraemia and possible adrenal insufficiency after major postpartum bleeding.
Investigations and management: Test pituitary axes; suspected cortisol deficiency requires urgent assessment and glucocorticoid treatment before thyroid replacement.
Stevens–Johnson syndrome / toxic epidermal necrolysis
What it is: Severe mucocutaneous adverse reactions with epidermal necrosis, often triggered by medicines; classification relates to body-surface-area detachment.
Recognition: Fever, skin pain, atypical target lesions, mucositis and evolving blistering after a new medicine.
Investigations and management: Immediately stop the suspected trigger and arrange emergency specialist care, eye assessment and supportive management.
T
Takayasu arteritis
What it is: Granulomatous large-vessel vasculitis involving the aorta and its major branches, typically arising in younger people.
Recognition: Limb claudication, unequal pulses or blood pressures, vascular bruits and systemic inflammation.
Investigations and management: Urgent vascular imaging and specialist rheumatology assessment guide treatment and monitoring.
Thrombotic thrombocytopenic purpura
What it is: Life-threatening thrombotic microangiopathy often caused by severe ADAMTS13 deficiency, leading to platelet-rich microthrombi.
Recognition: Thrombocytopenia and microangiopathic haemolytic anaemia, sometimes with neurological, renal or cardiac involvement; the classical pentad is often absent.
Investigations and management: Urgent haematology involvement and plasma-exchange pathway; do not wait for confirmatory ADAMTS13 before appropriate emergency treatment.
Turner syndrome
What it is: Sex-chromosome condition associated with complete or partial loss of one X chromosome; 45,X and mosaic forms occur.
Recognition: Short stature, gonadal insufficiency with delayed puberty or primary amenorrhoea, and increased frequency of coarctation, bicuspid aortic valve and renal anomalies.
Investigations and management: Confirm with karyotype and arrange specialist endocrine, cardiovascular and renal assessment; ongoing aortic surveillance is important.
U
Usher syndrome
What it is: Inherited condition combining sensorineural hearing loss with retinitis pigmentosa, with vestibular involvement in some subtypes.
Recognition: Hearing impairment followed by night blindness, peripheral field loss or balance problems.
Investigations and management: Ophthalmology, audiology and genetic counselling help define subtype and support communication and mobility.
V
Von Hippel–Lindau disease
What it is: Autosomal dominant tumour-predisposition syndrome associated with haemangioblastomas, clear-cell renal cancer, phaeochromocytoma and pancreatic lesions.
Recognition: CNS or retinal haemangioblastomas, renal masses or a strong family history.
Investigations and management: Confirm germline VHL involvement and coordinate lifelong multidisciplinary surveillance.
W
Wernicke encephalopathy
What it is: Neurological emergency caused by thiamine deficiency, often associated with alcohol-use disorder, malnutrition or prolonged vomiting.
Recognition: Confusion, eye movement abnormalities and gait ataxia; the complete triad is frequently absent.
Investigations and management: Give parenteral thiamine promptly in suspected cases and manage associated metabolic abnormalities without delaying treatment.
X
X-linked adrenoleukodystrophy
What it is: Peroxisomal disorder caused by ABCD1 variants, causing very-long-chain fatty acid accumulation with variable cerebral, spinal-cord and adrenal involvement.
Recognition: Progressive spastic paraparesis, adrenal insufficiency or childhood cognitive/neurological decline in an at-risk family.
Investigations and management: Very-long-chain fatty acids, ABCD1 testing and specialist endocrine/neurogenetic evaluation support diagnosis and surveillance.
Y
Yersinia enterocolitica infection
What it is: Enteric bacterial infection that can cause diarrhoea and terminal ileitis or mesenteric adenitis.
Recognition: Right iliac fossa pain can mimic appendicitis; post-infectious reactive arthritis may occur.
Investigations and management: Assess hydration and clinical severity; stool testing and antibiotic decisions depend on illness severity and risk.
Z
Zollinger–Ellison syndrome
What it is: Gastrin-secreting neuroendocrine tumour causing acid hypersecretion and refractory or multiple peptic ulcers; some cases occur with MEN1.
Recognition: Recurrent peptic ulceration, diarrhoea and severe reflux despite treatment.
Investigations and management: Fasting gastrin with simultaneous gastric acidity assessment and specialist endocrine/gastroenterology referral are needed; acid suppression complicates testing.