SECTION 5 Pathology

Alphabetical listing of pathologies 246

Diagnostic imaging 281

Electrodiagnostic tests 283

Alphabetical listing of pathologies

Acute respiratory distress syndrome (ARDS)

ARDS can be caused by a wide variety of factors including pneumonia, sepsis, smoke inhalation, aspiration, major trauma and burns. As a result, the body launches an inflammatory response that affects the alveolar epithelium and pulmonary capillaries. In ARDS the alveolar walls break down and the pulmonary capillaries become more permeable allowing plasma and blood to leak into the interstitial and alveolar spaces, while at the same time the capillaries become blocked with cellular debris and fibrin. The lungs become heavy, stiff and waterlogged and the alveoli collapse. This leads to ventilation/perfusion mismatch and hypoxaemia and patients normally require mechanical ventilatory support to achieve adequate gas exchange. Symptoms usually develop within 24–48 hours after the original injury or illness but can develop 5–10 days later.

Adhesive capsulitis

A condition that affects the glenohumeral joint synovial capsule and is characterized by a significant restriction of active and passive shoulder movement.

The aetiology is unknown but it has been linked to diabetes, heart disease, shoulder trauma or surgery, inflammatory disease, cervical disease and hyperthyroidism. The condition usually affects the middle-aged, particularly women. It normally follows three distinct phases, each lasting approximately 6–9 months (although this can be extremely variable):

Phase 1: increasing pain accompanied by increasing stiffness

Phase 2: decreasing pain with the stiffness remaining

Phase 3: decreasing stiffness and gradual return to normal function

Also known as frozen shoulder.

AIDS (acquired immunodeficiency syndrome)

Caused by infection with the human immunodeficiency virus (HIV), which destroys a subgroup of lymphocytes and monocytes, resulting in suppression of the immune system. The virus enters the host cell and causes a mutation of its DNA so that the host cell becomes an infective agent (known as the provirus). Signs and symptoms include fever, malaise, painful throat, swollen lymph nodes and aching muscles in the initial period following infection. After a variable period of latency (1–15 years) weight loss, night sweats, long-lasting fever and diarrhoea occur as AIDS itself develops, which eventually progresses to the acquisition of major opportunistic infections and cancers such as pneumonia or Kaposi’s sarcoma (a malignant skin tumour appearing as purple to dark brown plaques). Antiretroviral drugs are used to prolong the lives of infected individuals although there is no cure or vaccine for the disease.

Alzheimer’s disease

A form of dementia that is characterized by slow, progressive mental deterioration. Symptoms may start with mild forgetfulness, difficulty remembering names and faces or recent events and progress to memory failure, disorientation, speech disturbances, motor impairment and aggressive behaviour. It is the most common form of dementia and is distinguished by the presence of neuritic plaques (primarily in the hippocampus and parietal lobes), and neurofibrillary tangles (mainly affecting the pyramidal cells of the cortex). Definitive diagnosis is post-mortem.

Ankylosing spondylitis

A chronic inflammatory disease of synovial joints, involving the capsule and its attached ligaments and tendons. The spinal and sacroiliac joints are primarily affected, resulting in pain, stiffness, fatigue, loss of movement and function. Bone gradually forms in the outer layers of the annulus fibrosus and the anterior longitudinal ligament and, as the disease progresses, the vertebrae fuse together. ‘Bamboo spine’ is the term commonly used to describe its appearance on X-ray. The disease is more common in young males.

Asthma

A chronic inflammatory disease of the airways that makes them hyper-responsive to a wide range of stimuli including allergens, pollution, infection, exercise and stress. As a result the airways narrow, leading to coughing, wheezing, chest tightness and difficulty breathing. These symptoms can range from mild to severe; and may even result in death.

Baker’s cyst

Distension of the popliteal bursa, which may be accompanied by herniation of the synovial membrane of the knee-joint capsule forming a fluid-filled sac at the back of the knee. Associated with rheumatoid arthritis and osteoarthritis.

Bell’s palsy

An acute, lower motor neurone paralysis of the face, usually unilateral, related to inflammation and swelling of the facial nerve (VII) within the facial canal or at the stylomastoid foramen. Symptoms include inability to close the eye on the affected side, hyperacusis and impairment of taste. Good recovery is common.

Boutonnière deformity

A flexion deformity of the proximal interphalangeal joint combined with a hyperextension deformity of the distal interphalangeal joint. Caused by a rupture of the central slip of the extensor tendon at its insertion into the base of the middle phalanx. This causes the proximal phalanx to push upwards through the lateral slips. The most common causes are rheumatoid arthritis and direct trauma.

Broca’s dysphasia

A lesion of Broca’s area, on the inferior frontal cortex, causing non-fluent, hesitant speech that is characterized by poor grammar and reduced word output while meaning is preserved. Persistent repetition of a word or phrase (perseveration) can occur and writing may be impaired but comprehension remains relatively intact. Broca’s area is near the motor cortex for the face and arm and so may be associated with weakness in these areas.

Bronchiectasis

Dilatation and destruction of the bronchi as a result of recurrent inflammation or infection. It may be present from birth (congenital bronchiectasis) or acquired as a result of another disorder (acquired bronchiectasis). Causes of infection include impaired mucociliary clearance due to congenital disorders such as primary ciliary dyskinesia or cystic fibrosis as well as bronchial obstruction and impaired inflammatory response, either acquired after a severe episode of inflammation or secondary to immunodeficiency. The inability of the airways to clear secretions in the bronchi leads to a vicious circle of infection, damage and obstruction of the bronchi. Clinical features include: productive cough, episodic fever, pleuritic pain and night sweats. Patients may develop pneumothorax, respiratory and heart failure, emphysema and haemoptysis.

Bronchiolitis

A common respiratory problem affecting young infants. Caused by inflammation of the bronchioles due to infection by the human respiratory syncytial virus (RSV). Commonly occurs in winter. Signs and symptoms are similar to those of the common cold and include runny or blocked nose, temperature, difficulty feeding, a dry cough, dyspnoea and wheeze. In severe cases, hypoxia, cyanosis, tachypnoea and a refusal to eat may develop and hospitalization is necessary.

Bronchitis

An inflammation of the bronchi. Acute bronchitis is commonly associated with viral respiratory infections, i.e. the common cold or influenza, causing a productive cough, fever and wheezing. Chronic bronchitis is defined as a cough productive of sputum for 3 months a year for more than 2 consecutive years. It is characterized by inflammation of the airways leading to permanent fibrotic changes, excessive mucus production and thickening of the bronchial wall. This results in sputum retention and narrowing and obstruction of the airways. In severe cases irreversible narrowing of the airways leads to dyspnoea, cyanosis, hypoxia, hypercapnia and heart failure. These patients are often described as ‘blue bloaters’.

Brown-Séquard syndrome

A neurological condition that occurs when there is damage to one half of the spinal cord. Below the lesion there is motor loss on the same side and loss of pain and temperature on the opposite side.

Bulbar palsy

A bilateral or unilateral lower motor neurone lesion that affects the nerves supplying the bulbar muscles of the head and neck. Causes paralysis or weakness of the muscles of the jaw, face, palate, pharynx and larynx leading to impaired swallow, cough, gag reflex and speech.

Bursitis

Inflammation of the bursa caused by mechanical irritation or infection. Bursas that are commonly affected include the prepatellar, olecranon (can be associated with gout), subacromial, trochanteric, semimembranosus and the ‘bunion’ associated with hallux valgus. May or may not be painful.

Carpal tunnel syndrome

Compression of the median nerve as it passes beneath the flexor retinaculum, caused by inflammation due to joint disease, trauma, repetitive injury or during menopause. Characterized by pain, numbness, tingling or burning sensation in the distribution of the median nerve, i.e. the radial three and a half fingers and nail beds and the associated area of the palm. Symptoms are often worse at night. Patients also complain of clumsiness performing fine movements of the hand, particularly in the early morning.

Cerebral palsy

An umbrella term for a variety of posture and movement disorders arising from permanent brain damage incurred before, during, or immediately after birth. The disorder is most frequently associated with premature births and is often complicated by other neurological problems including epilepsy, visual, hearing and sensory impairments, communication and feeding difficulties, cognitive and behavioural problems. Common causes include intrauterine infection, intrauterine cerebrovascular insult, birth asphyxia, postnatal meningitis and postnatal cerebrovascular insult. The most common disability is a spastic paralysis, which can be associated with choreoathetosis (irregular, repetitive, writhing and jerky movements).

Charcot–Marie–Tooth disease

A progressive hereditary disorder of the peripheral nerves that is characterized by gradual progressive distal weakness and wasting, mainly affecting the peroneal muscle in the leg. Early symptoms include difficulty running and foot deformities. The disease is slowly progressive and in the late stages the arm muscles can also be involved. Also known as hereditary motor sensory neuropathy (HMSN).

Chondromalacia patellae

Refers to degeneration of the patellar cartilage causing pain around or under the patella. Common among teenagers and young adults, especially girls, it is linked to structural changes and muscle imbalance associated with periods of rapid growth. This leads to excessive and uneven pressure on patellar cartilage. May also result from an acute injury to the patella.

Chronic fatigue syndrome

A condition where patients complain of long-term, persistent fatigue along with other symptoms such as muscle pain, joint pains, disturbed sleep, poor concentration, headaches, sore throat and tender lymph nodes in the armpit and neck, though patients will not necessarily have all of them. Diagnosis is based on symptoms and tests that rule out other causes. No single cause of the disease has been established.

Chronic obstructive pulmonary disease (COPD)

An umbrella term for respiratory disorders that lead to obstruction of the airways. COPD is associated mainly with emphysema and chronic bronchitis but also includes chronic asthma. Risk factors include smoking, recurrent infection, pollution and genetics. Symptoms include cough, dyspnoea, excessive mucus production and chest tightness. Patients may also develop oedema and heart failure.

Claw toe

A flexion deformity of both the proximal interphalangeal and the distal interphalangeal joints combined with an extension deformity of the metatarsophalangeal joint.

Coccydynia

Pain around the coccyx. Often due to trauma, such as a fall onto the buttocks, or childbirth; however, the cause is often unknown.

Compartment syndrome

Soft tissue ischaemia caused by increased pressure in a fascial compartment of a limb. This increased pressure can have a number of causes but the main ones are swelling following major trauma, a cast being applied too tightly over an injured limb, or repetitive strain injury. Signs and symptoms are pain, pale/plum colour, absent pulse, paraesthesia and loss of active movement. If left untreated, it leads to necrosis of nerve and muscle in the affected compartment, which is known as Volkmann’s ischaemic contracture.

Complex regional pain syndrome (CRPS)

An umbrella term for a number of conditions, usually affecting the distal extremities, whose common features include unremitting severe pain (often described as burning) and autonomic changes in the affected region such as swelling, tenderness, restriction of movement, increased skin temperature, sweating, discoloration of the skin (usually blue or dusky red) and osteoporosis. CRPS is subdivided into two groups:

Group II – conditions where there has been an injury to a major peripheral nerve (e.g. sciatic nerve). Also referred to as causalgia (‘hot pain’).

Group I – conditions where minor or major trauma has occurred but there is no identifiable nerve injury, e.g. after Colles’ fractures. Also referred to as reflex sympathetic dystrophy and Sudeck’s atrophy.

Conversion disorder

A psychological disorder in which conflict or stress is ‘converted’ into physical symptoms such as blindness, deafness, loss of sensation, gait abnormalities, paralysis and seizures, for which no underlying cause can be found.

Coxa vara

Any condition that affects the angle between the femoral neck and shaft so that it is less than the normal 120–135°. It can be either congenital (present at birth), developmental (manifests clinically during early childhood and progresses with growth) or acquired (mal-united and non-united fractures, a slipped upper femoral epiphysis, Perthes’ disease and bone ‘softening’, e.g. osteomalacia, Paget’s disease).

Cubital tunnel syndrome

Compression of the ulnar nerve as it passes through the cubital tunnel (between the medial epicondyle and the olecranon). Symptoms include pain, weakness and dysaesthesia along the medial aspect of the elbow, forearm and hand.

Cystic fibrosis

A progressive genetic disorder of the mucus-secreting glands of the lungs, pancreas, mouth, gastrointestinal tract and sweat glands. Chloride ion secretion is reduced and sodium ion absorption is accelerated across the cell membrane, resulting in the production of abnormally viscous mucus. This thickened mucus lines the intestine and lung leading to malabsorption, malnutrition and poor growth as well as recurrent respiratory infections that eventually lead to chronic lung disease. The increased concentration of sodium in sweat upsets the mineral balance in the blood and causes abnormal heart rhythms. Other complications include male infertility, diabetes mellitus, liver disease and vasculitis. The disease is eventually fatal.

De Quervain’s syndrome

See ‘Tenovaginitis’.

Developmental dysplasia of the hip

Used to describe a spectrum of disorders causing hip dislocation either at birth or soon afterwards. The acetabulum is abnormally shallow so that the femoral head is easily displaced. Females and the left hip are more commonly affected.

Diabetes insipidus

A condition that leads to frequent excretion of large amounts of diluted urine. The symptoms of excessive thirst and urination are similar to diabetes mellitus but the two conditions are unrelated. Urine excretion is governed by antidiuretic hormone (ADH), which is made in the hypothalamus and stored in the pituitary gland. Diabetes insipidus is caused by damage to the pituitary gland or by insensitivity of the kidneys to ADH. This leads to the body losing its ability to maintain fluid balance.

Diabetes mellitus

A chronic condition caused by the body’s inability to produce or effectively use the hormone insulin to regulate the transfer of glucose from the blood into the cells. This leads to higher than normal levels of blood sugar. If not corrected this can lead to coma, kidney failure and ultimately, death. In the long term, high levels of glucose can damage blood vessels, nerves and organs leading to cardiovascular disease, chronic renal failure, retinal damage and poor wound healing.

There are two types of diabetes:

Type I – little or no insulin is produced. Requires lifelong treatment with insulin injections, diet control and lifestyle adaptations.

Type II – the body produces inadequate amounts of insulin or is unable to utilize insulin effectively. Mainly occurs in people over the age of 40 and is linked to obesity.

Diffuse idiopathic skeletal hyperostosis (DISH)

A condition that is characterized by widespread calcification and ossification of ligaments, tendons and joint capsule insertions. Mainly affects the spine with calcification of the anterior longitudinal ligament, which radiologically gives the appearance of candle wax dripping down the spine. Other joints may be affected with ossification of ligament and tendon insertions. Radiographically distinguishable from spondyloarthropathies and degenerative disc disease in that underlying bone and disc height are preserved and the facet joints are unaffected. It mainly affects men over 50 and is most cases it is asymptomatic, though some patients complain of stiffness and mild pain. The cause is unknown. Also known as Forestier’s disease.

Dupuytren’s contracture

Thickening and shortening of the palmar aponeurosis together with flexion contracture of one or more fingers. The cause is unknown.

Ehlers–Danlos syndrome (EDS)

A hereditary disorder of connective tissue that represents a collection of disorders (types I–X) characterized by a combination of joint hypermobility and hyperextensible (stretchy) skin. EDS types I and II are associated with mutations of collagen and feature high degrees of hypermobility, which may materialize in deformity or excessive dislocation. Type III, however, is associated with greater skin extensibility resulting in more obvious scarring or striae in the skin (in the thigh or lumbar region). The poorest prognosis is associated with EDS type IV, which results from a mutation in procollagen. Although rare, it commonly causes death through arterial rupture.

Emphysema

The walls of the terminal bronchioles and alveoli are destroyed by inflammation and lose their elasticity. This causes excessive airway collapse on expiration which traps air in the enlarged alveolar sacs. This irreversible airways obstruction leads to symptoms of dyspnoea, productive cough, wheeze, recurrent respiratory infection, hyperinflated chest and weight loss. These patients are often described as ‘pink puffers’ who may hyperventilate, typically overusing their accessory respiratory muscles, and breathe with pursed lips in order to maintain airway pressure to decrease the amount of airway collapse.

Empyema

A collection of pus in the pleural cavity following nearby lung infection. Can cause a build-up of pressure in the lung which causes pain and shortness of breath.

Enteropathic arthritis

This form of chronic inflammatory arthritis is associated with ulcerative colitis or Crohn’s disease, which are types of inflammatory bowel disease (IBD). It affects around a fifth of IBD sufferers and it mainly affects the peripheral joints such as the knees, ankles and elbows.

Fibromyalgia/fibrositis

A non-articular rheumatological disorder associated with widespread myofascial and joint pain and pain and tenderness in at least 11 of 18 trigger points. Other problems associated with fibromyalgia include fatigue, disturbed sleep, depression, anxiety and morning stiffness. The cause and pathogenesis of fibromyalgia is unknown, but it can either develop on its own or together with other conditions such as rheumatoid arthritis or systemic lupus erythematosus.

Forestier’s disease

See ‘Diffuse idiopathic skeletal hyperostosis’.

Freiberg’s disease

Degenerative aseptic necrosis of the metatarsal head, usually the second metatarsal head, which mainly affects athletic females aged 10–15 years.

Ganglion

An abnormal but harmless cystic swelling that often develops over a tendon sheath or joint capsule, especially on the back of the wrist.

Golfer’s elbow (medial epicondylitis)

Tendinopathy of the common origin of the forearm flexors causing pain and tenderness at the medial aspect of the elbow and down the forearm.

Gout

Characterized by attacks of acute joint inflammation secondary to hyperuricaemia (raised serum uric acid) where monosodium urate or uric acid crystals are deposited into the joint cavity. The disease usually affects middle-aged men and mainly affects the big toe. If the disease progresses, urates may be deposited in the kidney (stones) or the soft tissues (tophi), especially the ears. Further joint destruction can occur.

Guillain–Barré syndrome (GBS)

An acute inflammatory polyneuropathy that usually occurs 1–4 weeks after fever associated with viral infection or following immunization. Thought to be an autoimmune disorder, it leads to segmental demyelination of spinal roots and axons, denervation atrophy of muscle and inflammatory infiltration of the brain, liver, kidneys and lungs. Clinical features include loss of sensation in hands and feet, symmetrical progressive ascending motor weakness, paralysis, muscle wasting, diminished reflexes, pain and autonomic disturbances. In severe cases, the respiratory and bulbar systems are affected and ventilation/tracheostomy may be required. Recovery is common.

Haemothorax

Blood in the pleural cavity. Commonly due to chest trauma but also found in patients with lung and pleural cancer and in those who have undergone thoracic or heart surgery.

Hallux valgus

A lateral deviation of the great toe at the metatarsophalangeal joint. The metatarsal head becomes prominent (bunion) and, along with the overlying bursa, may become inflamed.

Hammer toe

An extension deformity of the metatarsophalangeal joint, combined with a flexion deformity of the proximal interphalangeal joint. The second toe is the most commonly affected.

Hereditary disorders of connective tissue

See ‘Joint hypermobility syndrome’, ‘Marfan syndrome’, ‘Ehlers–Danlos syndrome’, ‘Osteogenesis imperfecta’.

Herpes zoster

See ‘Shingles’.

Horner’s syndrome

A group of symptoms caused by a lesion of the sympathetic pathways in the hypothalamus, brainstem, spinal cord, C8–T2 ventral spinal roots, superior cervical ganglion or internal carotid sheath. It causes ipsilateral pupil constriction, drooping of the upper eyelid and loss of facial sweating on the affected side of the face.

Huntingdon’s disease

A hereditary disease caused by a defect in chromosome 4 that can be inherited from either parent. Onset is insidious and occurs between 35 and 50 years of age. Symptoms include sudden, involuntary movements (chorea) accompanied by behavioural changes and progressive dementia.

Hyperparathyroidism

Overactivity of the parathyroid glands leads to excessive secretion of parathyroid hormone (PTH), which regulates levels of calcium and phosphorus. Overproduction of PTH causes excessive extraction of calcium from the bones and leads to hypercalcaemia. Symptoms include fatigue, memory loss, renal stones and osteoporosis.

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