In this case scenario, the pH is too low to be fully explained by a respiratory acidosis. Usually, if there is a metabolic acidosis, the respiratory system will try to compensate by hyperventilation and reduced pCO2. In this case, however, the pCO2 is raised suggesting the presence of a respiratory component.Therefore, this boy has mixed metabolic and respiratory acidosis, most probably due to severe exacerbation of this asthma, which led to diabetic ketoacidosis.Note:Normal values:pH: 7.35 – 7.45pO2: 10 – 14 kPapCO2: 4.5 – 6 kPaBase excess (BE): -2 – 2 mmol/LHCO3: 22 – 26 mmol/L

Case control studies are used to determine the relationship between exposure to a risk factor and the resultant outcomes. It finds patients in the general population who have a certain condition and retrospectively searches for past exposure to possible risk factors for the disease. Controls are people who do not have the disease found in the general population. This type of study is useful for rare diseases, and is less time consuming to conduct. While cohort studies can be used to study rare diseases they measure the relative risk of developing the disease over time based on exposure. Ecological or cross-sectional studies attempt take a snapshot of a whole population, and thus are inappropriate for rare diseases as larger sample numbers are needed. A randomised control trial is better suited to determine the effect of an intervention.

Odds ratios are best described as the odds of an event in one group divided by the odds of the event in another. They form an alternative to the relative risk in case–control studies and are close to the relative risk when events are rare. The odds are the number of the event divided by the number without the event, which is less intuitive than the risk, which is the number with the event divided by the total. Odds ratios are therefore less intuitive than relative risks. Logistic regression analysis outputs variable coefficients which are the log of the odds ratio.

Based on the presenting features, the patient has developed a septal haematoma after the trauma. Septal hematoma:In this condition, blood collects between the septal cartilage and the perichondrium. The patient classically presents with symptoms of nasal difficulty and pain following a nasal injury. Care should be taken not to misdiagnose a septal haematoma as a blood clot on the septum. In the case of a septal haematoma the swelling will typically be visible on both sides of the septum although this is not always the case. Referral to an ENT surgeon is indicated because, if untreated, there is a high risk of cartilage breakdown and complications related to infection.Other options:- The nosebleed has now stopped therefore compression is no longer required. The boy has developed a septal haematoma after traumatic injury. – CT head is not indicated in this patient as the diagnosis is clearly a septal hematoma.- Management of a septal hematoma consists of drainage and antibiotics. There is no role for intranasal corticosteroids.- If untreated, there is a high risk of cartilage breakdown and complications related to infection. Thus, referral to the ENT is essential| reassurance and discharge can lead to complications.

The most appropriate action in this baby would be to perform HIV PCR and commence cART and PCP prophylaxis if HIV positive.Treatment guidelines for HIV-positive infants state that all should receive combination antiretroviral therapy (cART) and Pneumocystis jiroveci pneumonia (PJP) prophylaxis, irrespective of CD4 count or viral load.

The physical features and developmental delay are the key aspects in the given scenario. The child in question shows features of gross motor and social developmental delay and has physical features indicative of Prader-Willi syndrome (hypopigmentation, esotropia, disproportionately small hands and feet, loss of central muscle tone and undescended testes). Children with Prader-Willi syndrome can present with failure to thrive until ,12-18 months, at which point, hyperphagia and obesity become more prominent. Other options:- Although Klinefelter syndrome can present with delayed development, undescended/small testes and reduced muscle power, the presence of small hands/feet, hypopigmentation and failure to thrive are not characteristic features. – Marfan syndrome presents with different physical features (arachnodactyly, cardio-respiratory complications and skin changes, amongst others) than those associated with Prader-Willi syndrome. – DiGeorge can manifest with developmental delay, hypotonia and feeding difficulties. However, this clinical scenario does not report any of the typical facial features, hearing abnormalities or cardiac abnormalities that are typically caused by DiGeorge syndrome. – Russell-Silver syndrome can cause developmental abnormalities, poor muscle tone and power (poor head control and muscle function), feeding difficulties and poor growth during the post-natal period and infancy. However, characteristic facial (small, triangular face, blue sclerae) and skeletal abnormalities (limb asymmetry, finger abnormalities) are not present. Therefore, Prader-Willi syndrome is the most appropriate diagnosis for this patient.Note:Prader-Willi syndrome is an example of genetic imprinting where the phenotype depends on whether the deletion occurs on a gene inherited from the mother or father: In Prader-Willi syndrome, it is the paternal gene that is deleted from the long arm of chromosome 15, while in Angelman syndrome the maternal gene is deleted. Prader-Willi syndrome can occur due to the microdeletion of paternal 15q11-13 (70% of cases) maternal uniparental disomy of chromosome 15.

WHO states that diabetes can be diagnosed from a single fasting glucose of > 7.0 mmol/l with characteristic symptoms or a glucose level of > 11.1 mmol/l 2 hours after a glucose load. Two fasting glucose levels of > 7.0 mmol/l on separate occasions can also fit the diagnosis in the absence of characteristic symptoms.

Proteinuria refers to an increased amount of protein excretion in urine, which should be greater than 100mg/m2 per day on a single spot urine collection. The limit is even more relaxed for infants and neonates. Proteinuria is a prominent manifestation of cystinosis, acute tubular necrosis, Fanconi syndrome, and celiac disease. Landau-Kleffner syndrome is a rare childhood convulsive disorder, associated with acquired aphasia and auditory verbal agnosia.

The commonest time for bacterial meningitis is in the 1st month of life and group B Streptococcus is the commonest organism. The anterior fontanelle is full, but does not bulge with normal flexion. Neurological manifestations include seizures, irritability, poor tone, lethargy and tremors, however no findings of sensorineural deafness have been noted. One of the risk factors for introduction of meningeal infection is Meningomyelocele.

A ventricular septal defect (VSD) is a common form of congenital heart defects and is characterised by the presence of a hole in the wall that separates the right from the left ventricle. Medium or large defects can cause many complications. One of these complication is Eisenmenger syndrome, characterised by reversal of the shunt (from left-to-right shunt into a right-to-left) ,cyanosis and pulmonary hypertension.

The most probable diagnosis for this patient is bilateral retractile testes. This a normal phenomenon in some pre-pubertal boys. Rationale:Testicular descent can continue until about 3-months of age. The pre-pubertal testis is small enough that with activation of the cremasteric reflex, they can enter the inguinal canal. This in itself is a normal finding providing the testis can be brought into the scrotum without tension and does not require surgical correction. With time the testis will lie within the scrotum. Orchidopexy for true undescended testis can be performed from 6-months of age. It is also warranted if the testes remain undescended or intra-abdominally leading to infertility.Other options:- An ascending testis is one, typically, following hernia or orchidopexy surgery that was in the testis but with time is within the inguinal canal and cannot be brought into the scrotum. Orchidopexy is required for this.- No surgery is required as when the testis enlarges with puberty it will remain within the scrotum.- The testes can be brought into the scrotum. Therefore they are not undescended.- The testes are retractile not ascending| ascending testis cannot be brought into the scrotum and would require orchidopexy.

Erythema nodosum is the most common type of inflammation of the subcutaneous fat tissue, referred to as panniculitis. Erythema nodosum appears as painful, erythematous round lumps, usually symmetrically on the anterior aspect of lower extremities. These lesions are self-limiting and tend to resolve within 2-8 weeks without undergoing necrosis. There are various causes of erythema nodosum, but the most important among children is the streptococcal throat infection. Other causes include autoimmune conditions like sarcoidosis, inflammatory bowel disease, mycobacterial infection (TB), and drugs like penicillin and sulphonamides. Coeliac disease is not linked with the formation of erythema nodosum.

The most probable cause for the patient’s symptoms would be pes anserine bursitis.Translated, pes anserinus means goose feet. It is the term used to describe the unified bursa enclosing the tendons of the sartorius, gracilis and semitendinous muscles inserting into the anteromedial proximal tibia.Pes anserine bursitis is common in people doing sports due to overuse injuries. The main sign is of pain in the medial part of the proximal tibia. As the McMurray test is negative, medial meniscal injury is excluded.

Retinopathy of prematurity affects infants born early, and is due to the abnormal growth of retinal vasculature as opposed to vascular occlusion often see in adults. Though most babies with ROP can see normally, the most significant complication of ROP Is retinal detachment which can lead to blindness. Other structures in the eye such as the optic nerve or the fovea however, are not affected. Children may develop nystagmus as a result of poor sight in the affected eye(s).

The main cause of growth hormone (GH) deficiency is a pituitary tumour or the consequences of treatment of the tumour including surgery and/or radiation therapy.Sheehan’s syndrome (SS) is postpartum hypopituitarism caused by necrosis of the pituitary gland. It is usually the result of severe hypotension or shock caused by massive haemorrhage during or after delivery. Patients with SS have varying degrees of anterior pituitary hormone deficiency.Laron syndrome is Insulin-like growth factor I (IGF-I) deficiency due to GH resistance or insensitivity due to genetic disorders of the GH receptor causing GH receptor deficiency.

The most probable diagnosis in this patient would be febrile seizure plus syndrome.Rationale:All of the answers are possible epileptic conditions that this 8-year-old may have. However, the background history of febrile seizure together with a family history of febrile seizures, in a boy who is growing well, with no developmental delay, make febrile seizures plus the most appropriate differential diagnosis for this patient.Other options:- Epilepsy with myoclonic absences are often challenging to treat and may continue into adulthood. There is a male predominance (70%). At presentation, approximately half of cases have a learning disability. An absence seizure is common in this diagnosis and usually occurs daily.- Juvenile absence epilepsy may present with initial generalised tonic-clonic epilepsy followed by absences after that. They are also seen with a background of febrile seizure, and the peak age of presentation is usually at eight years old. Given the current history and lack of absences, this diagnosis is least likely.- Juvenile myoclonic epilepsy usually presents with a myoclonic seizure, although the presentation maybe with a generalised tonic-clonic seizure. It occurs more frequently. Background history of febrile fit may be present in 5-10% of the cases.- Temporal lobe epilepsy is usually associated with aura, and that is not seen in this patient.

Diagnostic criteria of PCOsAccording to the American Association of Clinical Endocrinologists, at least two of three of the criteria below are required for diagnosis of PCOS after excluding other causes of irregular bleeding and elevated androgen levels.Hyperandrogenism (clinical or laboratory)Oligo- and/or anovulationPolycystic ovaries on ultrasoundDiagnosis of PCOS is possible without the presence of ovarian cysts.Rule out any other causes of hyperandrogenism and anovulation.Blood hormone levels↑ Testosterone (both total and free) or free androgen index↑ LH (LH:FSH ratio > 2:1)Oestrogen is normal or slightly elevated A clinical picture of hyperandrogenism overrules any normal hormone levels and can fulfil a diagnostic criterium of PCOS.

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.

The most obvious sign of a congenital cataract in a child less than 1 year would be a strabismus/squint. A 12 month old child is unable to complain of loss of visual acuity and the child is likely to see well in one eye ruling out clumsiness. Amblyopia may also be difficult to test at this age unless it presents with the strabismus. ‘White’ red reflexes usually only present in very mature congenital cataracts.

Pierre Robin sequence is a condition present at birth, in which the infant has micrognathia, a tongue that is placed further back than normal (glossoptosis), and cleft palate. This combination of features can lead to difficulty breathing and problems with eating early in life. Pierre Robin sequence may occur isolated or be associated with a variety of other signs and symptoms (described as syndromic). The exact causes of Pierre Robin syndrome are unknown. The most common otic anomaly is otitis media, occurring 80% of the time, followed by auricular anomalies in 75% of cases. Hearing loss, mostly conductive, occurs in 60% of patients, while external auditory canal atresia occurs in only 5% of patients.

Being anatomically situated immediately posterior to the subclavius muscle and the medial part of the clavicle, the subclavian vein is at the highest risk of injury in the above patient.As a direct tributary of the brachiocephalic vein, it’s injury poses a high risk of massive bleeding.The brachiocephalic vein rests on the first rib, below and in front of the third part of the subclavian artery, and then on scalenus anterior which separates it from the second part of the artery (posteriorly).Anatomy of the clavicle:The clavicle extends from the sternum to the acromion and helps prevent the shoulder falling forwards and downwards.

Tinea corporis is a type of dermatophytosis, caused by Trichophyton or Microsporum. The disease is highly contagious and rapidly spreads to all the areas of the body, including the glabrous skin. It produces an erythematous itchy skin rash with a central area of clearance surrounded by raised scaly borders. Lesions can appear as concentric circles that overlap, referred to as tinea imbricate.

Endothoracic fascia: the connective tissue (fascia) that is between the costal parietal pleura and the inner wall of the chest wall.
Costomediastinal recess: the point where the costal pleura becomes mediastinal pleura.
Costodiaphragmatic recess: is the lowest point of the pleural sac where the costal pleura becomes diaphragmatic pleura.
Cupola: the part of the parietal pleura that extends above the first rib level into the root of the neck.
Costocervical recess: this is a made-up term.
Peritracheal fascia: a layer of connective tissue that invests the trachea.

Osteochondromas, or osteocartilaginous exostoses, are the most common benign bone tumours, and tend to appear near the ends of long bones. The overgrowth can occur in any bone where cartilage forms bone, and they are capped by cartilage. They are most common in people between the ages of 10-20 years old.

Live attenuated vaccines such as the MMR, should be avoided in HIV+ patients.

Crigler-Najjar syndrome is a rare genetic disorder characterized by an inability to properly convert and clear bilirubin from the body.The hallmark finding of Crigler-Najjar syndrome is a persistent yellowing of the skin, mucous membranes and whites of the eyes (jaundice).There are two forms of this disorder: Crigler-Najjar syndrome type I, characterized by a nearly complete lack of enzyme activity and severe, even life-threatening symptoms| and Crigler-Najjar syndrome type II, characterized by partial enzyme activity and milder symptoms. Both forms are inherited as autosomal recessive traits and are caused by errors or disruptions (mutations) of the UGT1A1 gene.The symptoms of Crigler-Najjar syndrome type I become apparent shortly after birth. Affected infants develop severe, persistent yellowing of the skin, mucous membranes and whites of the eyes (jaundice). These symptoms persist after the first three weeks of life.Infants are at risk for developing kernicterus, also known as bilirubin encephalopathy, within the first month of life.Crigler-Najjar syndrome type II is a milder disorder than type I. Affected infants develop jaundice, which increases during times when an infant is sick (concurrent illness), has not eaten for an extended period (prolonged fasting) or is under general anaesthesia. Some people have not been diagnosed until they are adults. Kernicterus is rare in Crigler-Najjar syndrome type II, but can occur especially when an affected individual is sick, not eating or under anaesthesia

Maternal and fetal toxoplasma infection may be avoided by advising pregnant women to wear gloves when gardening or handling cat litter and to cook meat thoroughly. Affected babies are treated with pyrimethamine, sulfadiazine, and folic acid.

The aetiology of macrocephaly is diverse.The most common cause is benign familial macrocephaly characterized by enlargement of the subarachnoid spaces and accounts for almost 50% of cases.Other causes are:- Enlargement of skull bones – Hyperostosis cranii – associated with disorders such as osteogenesis imperfecta, achondroplasia, and osteopetrosis- Secondary enlargement due to bone marrow expansion – as seen in thalassemia major- Increase in volume of cerebrospinal fluid- Hydrocephalus, Choroid plexus papilloma, Benign familial macrocephaly- Megalencephaly – Leukodystrophies – Canavan disease, Alexander disease, megalencephalic leukoencephalopathy with subcortical cysts- Lysosomal storage disorders – Tay-Sachs, mucopolysaccharidosis, gangliosidosis- Neurocutaneous disorders – Tuberous sclerosis, Sturge-weber syndrome, neurofibromatosis, Gorlin syndrome- Autism spectrum disorder- Other syndromes – Fragile X syndrome, Cowden syndrome, Sotos syndrome- Increased intracranial pressure (ICP)- CNS infections, Pseudotumor cerebriSubdural collections including hygromas- Mass lesions and an increase in the volume of bloodTumourIntraventricular haemorrhage, subdural hematoma, arteriovenous malformation

Power calculations are a important step in study design and preparation, but do not directly help with the interpretation of the results. They are used to determine how many subjects are needed in order to avoid errors in accepting or rejecting the null hypothesis. These calculations are not usually complex and for the best results, the power of the test should be set to above 80%.

Asthma patients have an increased risk of developing complications like pneumonia or collapsed lung. A clear visualization of the lungs through a CXR will define the management necessary for this patient.