Henoch–Schönlein purpura (HSP), also known as IgA vasculitis, is a disease of the skin, mucous membranes, and sometimes other organs that most commonly affects children. In the skin, the disease causes palpable purpura (small, raised areas of bleeding underneath the skin), often with joint pain and abdominal pain. It is an acute immunoglobulin A (IgA)–mediated disorder. The tetrad of purpura, arthritis, kidney inflammation, and abdominal pain is often observed.

Cataracts in infants are most commonly identified by an abnormal red reflex. Due to the high risk of amblyopia in unilateral cataracts, prompt referral to a paediatric ophthalmologist is indicated. Bilateral cataracts may occur in association with several syndromes or diseases, and these children require evaluation for these systemic disorders.Retinoblastoma is rare, but it is the most common primary intraocular tumour in children. About 80% of cases are diagnosed before age 4, with a median age at diagnosis of 2 years. It most frequently presents due to an abnormal red reflex. It is one of the few life-threatening disorders encountered in paediatric ophthalmology. Intraocular retinoblastoma is very treatable, but the mortality for metastatic disease is high. Identification of tumours before systemic spread is critical. Most children with large unilateral tumours will require enucleation (surgical removal of the eye), but the eye and vision may sometimes be preserved if the tumours are identified when they are small.

The most probable diagnosis for this patient, according to the clinical scenario provided is tuberous sclerosis. It is an autosomal-dominant disorder characterised by hamartomas located throughout the body, often prominently involving the central nervous system and skin. Two loci on chromosomes 9 and 16 have been identified to be associated with this condition. The condition has a variable expression and penetrance and is further characterised by:- Seizures (usually infantile spasms)- Developmental delay- Facial/cutaneous angiofibromas (adenoma sebaceum)- Periungual fibromas (pink projections from the nail folds)- Shagreen patches (leathery thickenings of the skin usually on the back) – Ash leaf macules (areas of depigmentation that become visible under a Wood’s light)- Fundoscopy may reveal white streaks along the fundal vessels.

Hypogonadism is found to be a feature in gigantism also known as acromegaly, a condition caused by growth hormone abnormalities. The most common cause of gigantism is a pituitary adenoma. Hypogonadism exists among other endocrinopathies found in gigantism. Other causes of hypogonadism include Kleinfelter’s syndrome, which is characterized by premature testicular failure. The other options listed, primary hypothyroidism, teratoma, tuberous sclerosis and hepatoblastoma are all associated with precocious puberty.

The most probable diagnosis for this patient would be external angular dermoid.External angular dermoids typically form where there are overlapping tissue planes such as the midline. They contain a caseous material. The cysts are essentially benign in nature and are excised for cosmetic purposes or when they encroach on vision.Other options:- Branchial remnant typically presents as a supraclavicular pit.- Sebaceous cysts tend to be present on the scalp.- There is nothing in the clinical scenario to suggest a vascular malformation such as pigment change or ‘bag of worms’.- Lymphatic malformations are typically found in the neck or under the axilla.

In secretory OM, effusion in the middle ear is present which does not produce any pain to the patient in comparison to acute OM which produces otalgia. The family members are the ones to notice hearing loss as the patient usually is not aware of it. On otoscopy, the features described in the question are prominent. Otitis externa is usually painful and it also produces an itching sensation. Chronic otitis media is painful and may interfere with balance problems. Cholesteatoma is an abnormal cystic growth in the middle ear that usually discharges foul-smelling fluids and as it grows, otalgia can appear.

Ataxic gait is not a direct association of Down’s syndrome. All other given responses are associated with Down’s syndrome.

The clinical scenario presented is highly suggestive of vitamin C deficiency (Scurvy).Vitamin C is found in citrus fruits, tomatoes, potatoes, Brussel sprouts, cauliflower, broccoli, cabbage and spinach. Deficiency leads to impaired collagen synthesis and disordered connective tissue. Scurvy is associated with severe malnutrition as well as drug and alcohol abuse, and those living in poverty with limited access to fruits and vegetables.Symptoms and signs include:- Follicular hyperkeratosis and perifollicular haemorrhage- Ecchymosis- Gingivitis with bleeding and receding gums- Sjogren’s syndrome- Arthralgia- Oedema- Impaired wound healing- Generalised symptoms such as weakness, malaise, anorexia and depression

Although initially thought to affect only boys, girls with DMD also have an estimated 10% chance of inheriting the condition. In girls, DMD may present with all or some clinical manifestations.

As this boy was dry for a considerable period, there is a high chance of a secondary cause for the bed wetting, such as bladder infections, constipation, diabetes, psychological stress and hormonal problems etc. These have to be excluded.

Graves disease is an autoimmune disorder in which patients present with thyrotoxicosis and related ophthalmopathy, and dermopathy. Many affected patients experience hyperthyroidism. Peak incidence of graves disease is after the 3rd decade of life and is more common in women than in men. Graves susceptibility is association with HLA-DR3. Clinical features of Graves disease include an increased metabolic rate, heat intolerance, irritability, weight loss despite increasing appetite, diarrhoea palpitations, chemosis, acropachy and onycholysis.

The child has experienced the Somogyi phenomenon. It is a phenomenon where there’s a morning rise in blood sugar. Often it occurs as posthypoglycemic hyperglycaemia and follows nocturnal hypoglycaemia. The mechanism is the production of counter-regulatory hormones like glucagon, cortisol and adrenaline, which increase glucose. She can be managed by reducing her evening insulin dosage and increasing complex carbohydrates for supper (evening meal).Type I diabetes mellitus:It is a chronic illness that is characterised by the inability to produce insulin. It is caused by autoimmune destruction of the beta cells in the pancreas and often presents with ketoacidosis.The patient can present with symptoms suggestive of polyuria, polydipsia, and weight loss. There can be periods of islet cell regeneration in these patients, which leads to a ‘honeymoon period’ of remission.Symptoms occur when there is < 20% of islet cell activity left.Insulin therapy is required in almost all children with type 1 diabetes.Most children require multiple insulin injections throughout the day via subcutaneous insulin pumps.Target HbA1c in these patients is 48 mmol/mol according to the updated NICE guidelines.

Various types of birthmarks are commonly seen in children of different age groups. Birthmarks can be broadly classified as pigmented and vascular birthmarks. Port-wine stain (nevus flammeus) is an example of a vascular birthmark, and is characterized by a reddish-purple discoloration of the skin due to abnormal underlying skin vasculature. Port-wine stain has also been associated with vascular diseases like Sturge-weber syndrome, which is a congenital neurocutaneous disorder. In Sturge-weber syndrome, the port-wine stain affects the skin around the ophthalmic branch of trigeminal nerve.

Cranial nerves I, II, and VIII are considered purely afferent nerves since they conduct sensory information from the olfactory region, the retina of the eye, and the inner ear structures, respectively.Cranial nerves III, IV, VI, XI, and XII are considered purely efferent due to their motor output to the orbit, the neck, and the tongue.Cranial nerves V, VII, IX, and X are considered mixed cranial nerves due to the presence of afferent and efferent fibres with both sensory and motor components.

Polycythaemia is described as an abnormal increase in the red cell mass. As this influences hyper-viscosity, a peripheral venous sample of blood haematocrit can be used to determine the packed cell volume. Polycythaemia is present if the venous haematocrit is >65% or <22g/dl if converted into a haemoglobin value. Though it is the method of choice for screening, capillary blood samples obtained though heel pricks in new-born may be as much as 15% higher than venous samples and thus high values must be confirmed with a venous sample.

The clinical features and the presentation of this child and the MRI findings are highly suggestive of acute lymphoblastic leukaemia.Anaemia and neutropenia, with a borderline platelet count as well as the tumour infiltration on both femurs on the MRI scan, are suggestive of a widespread Marrow disorder. Based on the age of the patient, acute lymphoblastic leukaemia is more appropriate as it is more common than acute myeloid leukaemia in children and can present with bony pain in this age group.Other options:- Acute myeloid leukaemia: Although this is the most common leukaemia that is seen in adults, it rarely presents in children. – Ewing’s sarcoma: This would usually present in a more unilateral manner, and would only be associated with cytopenia if there was direct bone marrow involvement.- HIV infection: It would be very rare in this group. HIV infection can cause a wide array of signs and symptoms, but we are told that the MRI scan is highly suggestive of tumour infiltration, which would be uncommon in this condition. – Juvenile arthritis: It is much less common. There is also nothing to find on examination, such as swollen or painful joints, which would usually be seen in this condition.

Adhesion formation might be reduced by minimally invasive surgical techniques and the use of adhesion barriers. Non-operative treatment is effective in most patients with ASBO. Contraindications for non-operative treatment include peritonitis, strangulation, and ischemia. When the adhesive aetiology of obstruction is unsure, or when contraindications for non-operative management might be present, CT is the diagnostic technique of choice. The principles of non-operative treatment are nil per os, naso-gastric, or long-tube decompression, and intravenous supplementation with fluids and electrolytes. When operative treatment is required, a laparoscopic approach may be beneficial for selected cases of simple ASBO.

Turner syndrome is a genetic disease that affects females. It presents with wide-spread nipples, low hairline, lymphoedema, short 4th metacarpals, high-arched palate, cardiac problems, and horseshoe kidneys.

Hirschsprung’s disease is characterized by congenital absence of the autonomic plexus (Meissner’s and Auerbach’s plexus) in the intestinal wall. Usually limited to the distal colon, it can occasionally involve the entire colon or even the small bowel. There is abnormal or absent peristalsis in the affected segment, resulting in continuous spasm of smooth muscle and partial/complete obstruction. This causes accumulation of intestinal contents and dilatation of proximal segment. Skip lesions are highly uncommon. This disease is seen early in life with 15% patients presenting in first month, 60% by 1 year of age and 85% by the age of 4 years. Symptoms include severe and complete constipation, abdominal distension and vomiting. Patients with involvement of ultra-short segments might have mild constipation with intervening diarrhoea. In older children, symptoms include failure to thrive, anorexia, and lack of an urge to defecate. On examination, an empty rectum is revealed with stool palpable high up in the colon. If not diagnosed in time, it can lead to Hirschsprung’s enterocolitis (toxic megacolon), which can be fulminant and lead to death. Diagnosis involves a barium enema or a rectal suction biopsy. Barium enema shows a transition in diameter between the dilated, normal colon proximal to the narrowed, affected distal segment. It is to be noted that barium enema should be done without prior preparation, which can dilate the abnormal segment, leading to a false-negative result. A 24-hour post-evacuation film can be obtained in the neonatal period – if the colon is still filled with barium, there is a high likelihood of Hirschsprung’s disease. Full-thickness rectal biopsy is diagnostic by showing the absence of ganglion cells. Acetylcholinesterase staining can be done to highlight the enlarged nerve trunks. Abnormal innervation can also be demonstrated by rectal manometry.

Treating persons infected with C. trachomatis prevents adverse reproductive health complications and continued sexual transmission, and treating their sex partners can prevent reinfection and infection of other partners. Treating pregnant women usually prevents transmission of C. trachomatis to neonates during birth. Chlamydia treatment should be provided promptly for all persons testing positive for infection. Treatment delays have been associated with complications (e.g. PID) in a limited proportion of women. To minimise disease transmission to sex partners, persons treated for chlamydia should be instructed to abstain from sexual intercourse for 7 days after single-dose therapy or until completion of a 7-day regimen and resolution of symptoms if present. To minimise risk for reinfection, patients also should be instructed to abstain from sexual intercourse until all of their sex partners are treated. Persons who receive a diagnosis of chlamydia should be tested for HIV, GC, and syphilis.

Most cases of Trisomy 18, also called Edwards syndrome, are not inherited but occur as random events during the formation of eggs and sperm. An error in cell division called nondisjunction results in a reproductive cell with an abnormal number of chromosomes. For example, an egg or sperm cell may gain an extra copy of chromosome 18. If one of these atypical reproductive cells contributes to the genetic makeup of a child, the child will have an extra chromosome 18 in each of the body’s cells.Mosaic trisomy 18 is also not inherited. It occurs as a random event during cell division early in embryonic development. As a result, some of the body’s cells have the usual two copies of chromosome 18, and other cells have three copies of this chromosome.Partial trisomy 18 can be inherited. An unaffected person can carry a rearrangement of genetic material between chromosome 18 and another chromosome. This rearrangement is called a balanced translocation because there is no extra material from chromosome 18. Although they do not have signs of trisomy 18, people who carry this type of balanced translocation are at an increased risk of having children with the condition.Canavan disease is a type of leukodystrophy and a degenerative disorder that causes progressive damage to nerve cells in the brain. It is inherited in an autosomal recessive manner.Cystic Fibrosis is the most common lethal recessive disease of white people, with a carrier frequency of 1:25 and is inherited in an autosomal recessive manner.Galactosaemic is autosomal recessive and due to mutations in the GALT gene.Phenylketonuria is the most common inborn error of metabolism in the UK with an incidence of 1:10,000 and a carrier rate of 1:50.

Protein energy malnutrition often presents in two common forms, Kwashiorkor and Marasmus. Kwashiorkor is characterised by a protein deficiency with an additional inadequate calorie intake. As a result, affected children present with oedema, muscular atrophy, and their weight for age is 60-80% of the expected weight. Their cutaneous tissue is however preserved. Marasmus on the other hand is characterised by a severe calorie deficiency leading to atrophy of the muscles and adipose tissue, with weight loss being less than 60% of the normal. In both cases, if the child is not promptly rehabilitated, the malnutrition could cause irreversible damage, such as hepatic, cardiac and renal impairments.

The external auditory canal (EAC) extends from the auricle to the tympanic membrane. Its lateral portion is fibrocartilaginous and its medial portion is bony. Its bony portion is formed by the tympanic portion of the temporal bone.

Presentation can vary by individual. Early stages are often characterized by malaise, fatigue, and lethargy. One to 3 months of inadequate intake can lead to anaemia, myalgia, bone pain, easy bruising (Figure 3), swelling, petechiae, perifollicular haemorrhages, corkscrew hairs, gum disease, poor wound healing, mood changes, and depression. Perifollicular haemorrhages and easy bruising are often first seen in the lower extremities, as capillary fragility leads to an inability to withstand hydrostatic pressure. Late stages of scurvy are more severe and life threatening| common manifestations include generalized oedema, severe jaundice, haemolysis, acute spontaneous bleeding, neuropathy, fever, convulsions, and death.

The clinical presentation is typical of a slipped femoral epiphysis, which refers to a fracture through the growth plate (physis), resulting in slippage of the overlying end of the femur. It is the most common hip disorder in adolescence. SCFEs usually cause groin pain on the affected side, but sometimes cause knee or thigh pain. The range of motion in the hip is restricted in internal (medial) rotation, abduction, and flexion.

The mesonephric duct is one of the paired embryogenic tubules that drain the primitive kidney (mesonephros) to the cloaca. It also gives off a lateral branch forming the ureteric bud. In both the male and the female the Wolffian duct develops into the trigone of the urinary bladder. When the ducts are exposed to testosterone during embryogenesis, male sexual differentiation occurs: the mesonephric duct develops into the rete testis, the ejaculatory ducts, the epididymis, the ductus deferens and the seminal vesicles.

An enlarged lymph node does not necessarily need treatment especially if it is caused by a virus. If it is bacterial, antibiotics should be prescribed. Amoxicillin is first line treatment in non-penicillin allergic patients and side effects include allergic reactions like skin rash and itching

Sepsis can be described as a condition in which there is a dysregulated inflammatory response to an infection. In the case of neonates, sepsis can be life threatening and may present with respiratory distress more than 4 hours after birth, shock, seizures, and multi organ failure. Risk factors that further point to sepsis include prolonged rupture of maternal membranes for more than 24 hours before birth, a history of a maternal fever during labour, or parenteral antibiotic treatment given to the mother for a suspected or confirmed bacterial infection.

Pityriasis amiantacea is a reaction pattern rather than a specific diagnosis. Common conditions that may present with pityriasis amiantacea include:Scalp psoriasisSeborrhoeic dermatitisAtopic dermatitisTinea capitis.Head lice and lichen simplex should also be considered.When no underlying cause is found, the condition is often called idiopathic pityriasis amiantacea.

The likely diagnosis in this case is Haemolytic Uremic Syndrome (HUS), which is generally seen in young children presenting with a triad of symptoms, namely: acute renal failure, microangiopathic haemolytic anaemia, and thrombocytopenia. The typical cause of HUS is ingestion of a strain of Escherichia coli.

The likely diagnosis in this case is Haemolytic Uremic Syndrome (HUS), which is generally seen in young children presenting with a triad of symptoms, namely: acute renal failure, microangiopathic haemolytic anaemia, and thrombocytopenia. The typical cause of HUS is ingestion of a strain of Escherichia coli. The laboratory results will usually include fragmented RBCs, decreased serum haptoglobin, reduced platelet count, nonspecific WBC changes, and normal coagulation tests (PTT included).

Classic Kallmann syndrome (KS) is due to isolated hypogonadotropic hypogonadism. Most patients have gonadotropin-releasing hormone (GnRH) deficiency, as suggested by their response to pulsatile GnRH therapy. The hypothalamic-pituitary function is otherwise normal in most patients, and hypothalamic-pituitary imaging reveals no space-occupying lesions. By definition, either anosmia or severe hyposmia is present in patients with Kallmann syndrome.

This is the clinical picture of dermatitis herpetiformis associated with gluten-sensitive enteropathy. To establish the diagnosis, you should measure the coeliac antibodies. Darrier’s sign (where the skin urticates when it is stroked) is positive in urticaria pigmentosa.

Hypospadias is an abnormality of anterior urethral and penile development. The urethral opening is located on the ventral aspect of the penis proximal to the tip of the glans penis, which, in this condition, is open. The urethral opening may be located as proximal as in the scrotum or perineum. The penis may also have associated ventral shortening and curvature, called chordee, with more proximal urethral defects.

The most probable diagnosis for this patient’s symptoms is psoriasis. Psoriasis:Chronic plaque psoriasis is characterised by pinkish-red hyperkeratotic plaques, which occur mainly on extensor surfaces such as knees and elbows. The lower back, ears and scalp can also be involved. Koebner phenomenon: Psoriasis typically exhibits this phenomenon where new plaques of psoriasis occur particularly at sites of skin trauma. Diagnosis:Skin biopsy of psoriatic plaques reveals acanthosis and parakeratosis, reflecting increased skin turnover. Capillary dilatation within the dermis also occurs, surrounded by a mixed neutrophilic and lymphohistiocytic perivascular infiltrate.

Narcolepsy is a rare condition characterised by excessive daytime sleepiness, sleep paralysis, hypnagogic hallucinations, and cataplexy (sudden collapse triggered by emotion such as laughing or crying). There is no cure for narcolepsy. Treatment options include stimulants, such as methylphenidate (Ritalin) or modafinil (Provigil), antidepressants, such as fluoxetine (Prozac), citalopram (Celexa), paroxetine (Paxil), sertraline (Zoloft) and sodium oxybate (Xyrem). Modafinil has replaced methylphenidate and amphetamine as the first-line treatment of excessive daytime sleepiness (EDS).

The correct answer is triple X syndrome with a genotype of XXX and an almost normal female phenotype. The extra X chromosome is inactive. The final phenotype of an individual is determined after normal sexual and gonadal differentiation, a process that involves several genes located on chromosomes X and Y. Disorders of sexual differentiation result in cases of ambiguous genitalia and are caused by a number of genetic abnormalities. Among these disorders is the turner syndrome with a genotype of 45X0, characterized by gonadal dysgenesis and ovarian failure. DAX-1 gene mutation leads to congenital adrenal hypoplasia and hypogonadotropic hypogonadism, which results in virilization of female external genitalia. Campomelic dysplasia results from mutation of the SOX-9 gene, leading to 46XY sex reversal. Danys-Drash syndrome is characterized by disordered sexual development in affected males due to the mutated WT-1 gene, which also causes Wilm’s tumour.

The boy seems to have a varicocele so the most appropriate next step would be reassurance. A varicocele is an enlargement of the veins within the scrotum called the pampiniform plexus. A varicocele only occurs in the scrotum and is very similar to varicose veins that can occur in the leg. Because a varicocele usually causes no symptoms, it often requires no treatment.

Haemophilia A has an X-linked recessive pattern of inheritance, meaning that is a 50% chance of having a son with haemophilia and 50% chance of the daughters being carriers of the haemophilia gene.

Most cases of Prader-Willi syndrome are not inherited, particularly those caused by a deletion in the paternal chromosome 15 or by maternal uniparental disomy. These genetic changes occur as random events during the formation of reproductive cells (eggs and sperm) or in early embryonic development. Affected people typically have no history of the disorder in their family.Rarely, a genetic change responsible for Prader-Willi syndrome can be inherited. For example, it is possible for a genetic change that abnormally inactivates genes on the paternal chromosome 15 to be passed from one generation to the next.Prader-Willi syndrome is a complex genetic condition that affects many parts of the body. In infancy, this condition is characterized by weak muscle tone (hypotonia), feeding difficulties, poor growth, and delayed development. Beginning in childhood, affected individuals develop an insatiable appetite, which leads to chronic overeating (hyperphagia) and obesity. Some people with Prader-Willi syndrome, particularly those with obesity, also develop type 2 diabetes (the most common form of diabetes).

The endocardial cushions in the heart are the mesenchymal tissue that make up the part of the atrioventricular valves, atrial septum and ventricular septum. An incomplete fusion of these mesenchymal cells can cause an atrioventricular septal defect. The terms endocardial cushion defect, atrioventricular septal defect and common atrioventricular canal defect can be used interchangeably with one another.

Marfan syndrome is a disorder that affects the connective tissue found throughout the body, Marfan syndrome can affect many systems, often causing abnormalities in the heart, blood vessels, eyes, bones, and joints. The two primary features of Marfan syndrome are vision problems caused by a dislocated lens (ectopia lentis) in one or both eyes and aortic root disease, leading to aneurysmal dilatation, aortic regurgitation and dissection is the main cause of morbidity and mortality in Marfan syndrome.

Consuming iron in its Fe2+ (ferrous form) form can improve the ability to absorb dietary iron in patients with iron deficiency anaemia (IDA). Clinical features of IDA include:- Koilonychia- Atrophic glossitis- Post-cricoid webs- Angular stomatitisThe peripheral blood smear shows the following abnormal RBC morphologies:- Target cells- Pencil poikilocytes- Microcytic-hypochromic cells

The Chi-squared test evaluates if two variables are related. The other statistical tests mentioned do not perform this function.

Bulimia nervosa is an eating disorder that involves frequent episodes of binge eating followed by inappropriate purging behaviour. The underlying reason for this behaviour is distorted self-image. Bulimia leads to several medical issues, including various laboratory derangements. Among these deranged laboratory parameters are the hormone cholecystokinin, which is found to be decreased in women having bulimia. It is hypothesized that the bingeing episodes observed in patients with bulimia are due to lower levels of CCK since normal levels of CCK are involved in maintaining satiety and controlling the urge to binge eat.

The prognosis for croup is excellent, and recovery is almost always complete with complications being quite rare. The possible complications are pneumonia, bacterial tracheitis, pulmonary oedema, pneumothorax, pneumomediastinum, lymphadenitis or otitis media. Bacterial tracheitis is a life-threatening infection that can arise after the onset of an acute viral respiratory infection.

From the midgut derives most of the small intestine as well as some parts of the large intestine, including the appendix. The appendix is at the base of caecum, up to 10cm long and mainly comprised of lymphoid tissue (Hence mesenteric adenitis may mimic appendicitis).

Projectile vomiting is the hallmark symptom of hypertrophic pyloric stenosis. It is the most common cause of intestinal obstruction in infancy, which has a male-to-female predominance of 4-5:1. Current management recommendations include ultrasonography for diagnosis, correction of electrolytes, and surgical intervention.

Scaphoid fractures are regarded as fractures that are difficult to heal, so a classification system is needed taking different factors into account that should lead towards proper guidance to the healing time and management of these fractures. Popular classification criteria are Herbert, Russe, and Mayo classification systems. Herbert’s classification system is based on the fracture’s stability and proposes that all complete bicortical fractures (except for tubercle fractures) are unstable. Salter-Harris classification is used for categorizing epiphyseal fractures, while Delbert classification system is reserved for fractures of the proximal femur in children. Fractures of the ankles are classified using Ottawa rules, and Garland classification is used for supracondylar fractures in children.

Bitemporal hemianopia is a characteristic finding seen in patients with optic chiasm lesion.The pituitary gland is situated within the pituitary fossa. Just above the pituitary fossa is the optic chiasm and so any expanding masses from the pituitary gland commonly press on it, causing bitemporal hemianopia.Other options:- Compression of the optic nerve would not cause more severe, generalised visual loss. Also, the optic nerve is not anatomically related to the pituitary gland and so is unlikely to be directly compressed in the presence of a pituitary tumour.- The optic tract is again not closely anatomically related with the pituitary gland and so is unlikely to be directly compressed in the presence of a pituitary tumour. Also, damage to the optic tract on one side would cause homonymous hemianopia.- The lateral geniculate nucleus is a centre of cells in the thalamus and is unlikely to be compressed by a pituitary tumour. Its function is to convey sensory information from the optic tract to more central parts of the visual pathway.- The Edinger-Westphal nucleus is located at the level of the superior colliculus in the midbrain and so may not be compressed by an enlarging pituitary tumour.Other visual defects:- Left homonymous hemianopia: It is the visual field defect to the left, due to the lesion of the right optic tract.- Homonymous quadrantanopias are seen in parietal (inferior homonymous quadrantopia) and temporal lobe lesions (superior homonymous quadrantopia). Mnemonic: PITS (Parietal-Inferior, Temporal-Superior)A congruous defect means complete or symmetrical visual field loss, and conversely, an incongruous defect is incomplete or asymmetric.Incongruous defects suggest an optic tract lesion, while congruous defects suggest optic radiation or occipital cortex lesion.