Cystic fibrosis is a progressive, genetic disease. A defective gene causes a thick, sticky build-up of mucus in the lungs, pancreas, and other organs. In the lungs, the mucus clogs the airways and traps bacteria leading to infections, extensive lung damage, and eventually, respiratory failure. In the pancreas, the mucus prevents the release of digestive enzymes that allow the body to break down food and absorb vital nutrients. Since the digestive enzymes are not being made, the food is not completely digested making them bulky, smelly, and hard to flush away. Finger clubbing is a prominent feature of cystic fibrosis on most patients.

Key observations in the results:

1. Oxygen Saturation Step-Up:
   • There is a significant step-up in oxygen saturation from the right ventricle (72%) to the pulmonary artery (86%). This suggests the presence of left-to-right shunting of blood.
2. Pressure Differences:
   • The pressure in the pulmonary artery is elevated (53/13 mmHg), indicating pulmonary hypertension.

Differential Diagnosis:

1. Patent Ductus Arteriosus (PDA):
   • PDA can cause increased pulmonary blood flow, leading to a step-up in oxygen saturation in the pulmonary artery. The pulmonary artery pressures can also be elevated due to increased blood flow.
2. Primary Pulmonary Hypertension:
   • Typically presents with elevated pulmonary pressures but does not usually show a step-up in oxygen saturation.
3. Pulmonary Stenosis:
   • Would result in elevated right ventricular pressure but would not explain the step-up in oxygen saturation.
4. Septum Primum Atrial Septal Defect (ASD):
   • Would result in a step-up in oxygen saturation from the right atrium to the right ventricle, not between the right ventricle and pulmonary artery.
5. Tetralogy of Fallot:
   • Characterized by right ventricular outflow tract obstruction, VSD, right ventricular hypertrophy, and an overriding aorta. Oxygen saturation levels would typically be lower in the systemic circulation.

A case–control study (also known as case–referent study) is a type of observational study in which two existing groups differing in outcome are identified and compared on the basis of some supposed causal attribute. Case–control studies are often used to identify factors that may contribute to a medical condition by comparing subjects who have that condition/disease (the cases) with patients who do not have the condition/disease but are otherwise similar (the controls).
An odds ratio (OR) is a statistic that quantifies the strength of the association between two events, A and B. The odds ratio is defined as the ratio of the odds of A in the presence of B and the odds of A in the absence of B or vice versa.

Epilepsy is a common paediatric neurologic disorder characterized by seizures of varying frequency and intensity. There are many childhood or infantile epilepsy syndromes that can be categorized as benign epilepsy syndromes as the child suffering from these usually outgrows them after reaching a certain age, and they do not lead to significant cognitive or physical impairment. Some of these may not need any treatment. Such benign epilepsy syndromes include benign rolandic epilepsy, Panayiotopoulos syndrome, Gastaut type-idiopathic childhood occipital epilepsy, and idiopathic photosensitive occipital lobe epilepsy. West syndrome, also called infantile spasms, is a serious infantile epileptic encephalopathy, characterized by multiple clusters of myoclonic spasms, and regression of the previous normally attained milestones. It is associated with severe cognitive and physical impairment, often leading to life long disability.

The most probable diagnosis for the patient in question is atrioventricular nodal re-entrant tachycardia (AVNRT).The presenting features of the patient are suggestive of supraventricular tachycardia (SVT). The most common form of SVT in children over 8 years old is atrioventricular nodal re-entrant tachycardia. It occurs as a result of an additional electrical circuit in or near the AV node itself.Other options:- Atrial Flutter: is a form of re-entry tachycardia within the atria which then becomes unsynchronised with the ventricles, which is not the case here. Furthermore, it is most common in babies and children with congenital heart disease.- Atrial tachycardia: is a condition where an area of atrium takes over the pacemaker activity of the heart. However, it is relatively uncommon.- Atrioventricular re-entrant tachycardia (AVRT): occurs due to an accessory electrical pathway between the atria and ventricles forming a re-entry circuit. This is the most common cause of SVT in children < 8 years old. One of the specific diagnoses of AVRT is Wolff-Parkinson-White syndrome. However, WPW syndrome is much rarer than AVNRT.- Premature atrial contractions (PACs): are very common in normal, healthy children and adolescents. Occasionally, they can give rise to the feeling of a 'skipped beat'. Fortunately, they are rarely associated with any significant underlying pathology or need to be treated.

Puberty is the general term for the transition from sexual immaturity to sexual maturity. There are two main physiological events in puberty:- Gonadarche is the activation of the gonads by the pituitary hormones follicle-stimulating hormone (FSH) and luteinizing hormone (LH).- Adrenarche is the increase in production of androgens by the adrenal cortex. It is the term for the maturational increase in adrenal androgen production that normally becomes biochemically apparent at approximately six years of age in both girls and boysA number of other terms describe specific components of puberty:- Thelarche is the appearance of breast tissue, which is primarily due to the action of oestradiol from the ovaries. – Menarche is the time of first menstrual bleed. – Pubarche is the appearance of pubic hair, which is primarily due to the effects of androgens from the adrenal gland. The term is also applied to first appearance of axillary hair, apocrine body odour, and acne.The earliest detectable secondary sexual characteristic on physical examination in most girls is breast/areolar development (thelarche). Ovarian enlargement and growth acceleration typically precede breast development but are not apparent on a single physical examination. Oestrogen stimulation of the vaginal mucosa causes a physiologic leukorrhea, which is a thin, white, non-foul-smelling vaginal discharge that typically begins 6 to 12 months before menarche. Menarche occurs, on average, 2 to 2.5 years after the onset of puberty

Keratosis pilaris most often affects the outer aspect of both upper arms. It may also occur on the thighs, buttocks and sides of the cheeks, and less often on the forearms and upper back. The distribution is symmetrical.The scaly spots may appear skin coloured, red (keratosis pilaris rubra) or brown (hyperpigmented keratosis pilaris). They are not itchy or sore.Macules are flat, nonpalpable lesions usually < 10 mm in diameter.Examples include freckles, flat moles, tattoos, and port-wine stains, and the rashes of rickettsial infections, rubella, measles (can also have papules and plaques), and some allergic drug eruptions.Papules are elevated lesions usually < 10 mm in diameter that can be felt or palpated. Examples include nevi, warts, lichen planus, insect bites, seborrheic keratoses, actinic keratoses, some lesions of acne, and skin cancers. Plaques are palpable lesions > 10 mm in diameter that are elevated or depressed compared to the skin surface. Plaques may be flat topped or rounded. Lesions of psoriasis and granuloma annulare commonly form plaques.Nodules are firm papules or lesions that extend into the dermis or subcutaneous tissue. Examples include cysts, lipomas, and fibromas.Vesicles are small, clear, fluid-filled blisters < 10 mm in diameter. Vesicles are characteristic of herpes infections, acute allergic contact dermatitis, and some autoimmune blistering disorders (e.g., dermatitis herpetiformis).Bullae are clear fluid-filled blisters > 10 mm in diameter. These may be caused by burns, bites, irritant contact dermatitis or allergic contact dermatitis, and drug reactions. Classic autoimmune bullous diseases include pemphigus vulgaris and bullous pemphigoid. Bullae also may occur in inherited disorders of skin fragility.

Increasing the volume of the TV and the child’s loss of hearing may suggest that he has otitis media with effusion but the fever and the ear pain and fever strongly points to otitis externa as the diagnosis.

Auscultatory findings of VSD vary with the size of the defect. Small VSDs typically produce murmurs ranging from a grade 1 to 2/6 high-pitched, short systolic murmur (due to tiny defects that actually close during late systole) to a grade 3 to 4/6 holosystolic murmur (with or without thrill) at the lower left sternal border| this murmur is usually audible within the first few days of life (see table Heart Murmur Intensity). The precordium is not hyperactive, and the 2nd heart sound (S2) is normally split and has normal intensity.Moderate to large VSDs produce a holosystolic murmur that is present by age 2 to 3 wk| S2 is usually narrowly split with an accentuated pulmonary component. An apical diastolic rumble (due to increased flow through the mitral valve) and findings of heart failure (e.g., tachypnoea, dyspnoea with feeding, failure to thrive, gallop, crackles, hepatomegaly) may be present. In moderate, high-flow VSDs, the murmur is often very loud and accompanied by a thrill (grade 4 or 5 murmur). With large defects allowing equalization of left ventricular and right ventricular pressures, the systolic murmur is often attenuated.

Craniopharyngiomas (also known as Rathke pouch tumours, adamantinomas or hypophyseal duct tumours) affect children mainly between the age of 5 and 10 years. It constitutes 9% of brain tumours affecting the paediatric population. These are slow-growing tumours which can also be cystic, and arise from the pituitary stalk, specifically the nests of epithelium derived from Rathke’s pouch. Histologically, this tumour shows nests of squamous epithelium which is lined on the outside by radially arranged cells. Calcium deposition is often seen with a papillary type of architecture.
ACTH-secreting pituitary adenomas are rare and mostly microadenomas. Paediatric astrocytoma’s usually occur in the posterior fossa. Although null cell adenomas can cause mass effect and give rise to the described symptoms, they are not suprasellar. Prolactinomas can also show symptoms of headache and disturbances in the visual field, however they are known to be small and slow-growing.

Age (years) Respiratory rate (per minute) Heart rate (per minute) Systolic blood pressure<1 30-40 110-160 70-901-2 25-35 100-150 80-952-5 25-30 95-140 80-1005-12 20-25 80-120 90-110>12 15-20 60-100 100-120Adapted from Advanced Paediatric Life Support Manual

Erythema multiforme lesions typically heal without scarring. Other options:- In erythema multiforme, lesions are typically symmetrical and acral, i.e. on the hands, feet and limbs. – HSV is a common cause of erythema multiforme in children, accounting for at least 50% of cases| the lesions typically have damaged skin in the centre and are dusky and bullous (in contrast to urticaria, where the centre of the lesion is normal).

Combined oral contraceptive pills have an anti ovulatory function and also reduce the pain of menstruation.

This is a case of an anaphylactic reaction that requires immediate intervention. IM adrenaline dose for 6-12 year old children is 300 micrograms IM.

Ideally, the test is done in the first 4 to 5 weeks, but it can be done at up to 3 months of age.The identification of all new-borns with hearing loss before age 6 months has now become an attainable realistic goal. In the past, parents and paediatricians often did not suspect a hearing loss until the age of 2-3 years, after important speech and language milestones have not been met. By the time these milestones are missed, the hearing-impaired child has already experienced irreversible delays in speech and language development.

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.

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.

Tuberous sclerosis presents with the growth of numerous noncancerous (benign) tumours in many parts of the body. They may appear in the brain, kidneys, skin or various other organs.

Advanced paternal age is associated with poor quality sperm leading to a reduction in overall fertility along with an increase in the occurrence of various medical disorders in the fetus. Advanced paternal age has been implicated as a risk factor for diseases like retinoblastoma, Marfan’s syndrome, neurofibromatosis, achondroplasia, autism spectrum disorders, schizophrenia, and acute lymphoblastic leukaemia. Down’s syndrome is mostly considered a consequence of advanced maternal age, but advanced paternal age has also been implicated as a risk factor. Turner syndrome is not found to be caused by advanced paternal age.

Anorexia nervosa is an eating disorder defined by restriction of energy intake relative to requirements, leading to a significantly low body weight. Patients will have an intense fear of gaining weight and distorted body image with the inability to recognize the seriousness of their significantly low body weight. Athletes in sports such as ballet, long-distance running, and martial arts are pressured to maintain lean body weights to outperform the competition.

Vesicoureteric reflex (VUR) is described as the retrograde flow of urine from the bladder into the ureter due to an incompetent uterovesical junction. In primary VUR the lower urinary tract functions normally, while secondary VUR is associated with a poorly functioning lower urinary tract. The incidence of VUR is highest in new-born girls. They can present with hydronephrosis, or urinary tract infections.

Pityriasis rosea is a common, acute exanthem of uncertain aetiology. Viral and bacterial causes have been sought, but convincing answers have not yet been found. Pityriasis rosea typically affects children and young adults. It is characterized by an initial herald patch, followed by the development of a diffuse papulosquamous rash. The herald patch often is misdiagnosed as eczema. Pityriasis rosea is difficult to identify until the appearance of characteristic smaller secondary lesions that follow Langer’s lines (cleavage lines). Several medications can cause a rash similar to pityriasis rosea, and several diseases, including secondary syphilis, are included in the differential diagnosis. Typically, only symptomatic treatment of pruritus with lotions, oral antihistamines, and/or a short course of topical steroids is necessary.

Prophylactic antibiotics should be given to the child to avoid infections and renal injury.

Lung buds are formed by 4-5 weeks of gestation.Development of the respiratory tract has five stages:- Embryonic (at 4 – 5 weeks of gestation):Formation of lung buds, trachea and mainstem bronchi occur. These structures are formed from a ventral outpouching of foregut pharynx. At this stage, the beginnings of the five lung lobes are present.- Pseudoglandular (at 5 – 16 weeks of gestation):Formation of terminal bronchioles, cartilage and smooth muscles occur in this stage. Adult numbers of airways proximal to acini are in place.- Canalicular (at 16-24 weeks gestation): Differentiation of type I and II epithelial cells can be done in this stage. There is also an increase in the size of proximal airways).- Saccular (at 24 – 40 weeks of gestation): Terminal saccule formation occurs. Production of surfactant takes place at this stage with an increase in the number of goblet cellsUp to half the adult number of alveoli are in place by this stage.- Alveolar (occurs between 32 weeks of gestation till the post-natal age 8): Formation of alveoli and septation occurs with the expansion of air spaces.

Answer: The burn area is extremely painful until skin graftedThird-degree burns destroy the epidermis and dermis. Third-degree burns may also damage the underlying bones, muscles, and tendons. The burn site appears white or charred. There is no sensation in the area since the nerve endings are destroyed. These are not normally painful until after skin grafting is done since the nerve endings have been destroyed.

The main aim of randomisation in a clinical trial is to remove the bias and avoid any potential confounding variables. While in double blind studies both the investigators and the patients are not aware of which group they belong in, being blind is not essential in carrying out a randomized study, nor is it essential that the randomisation be done away from the study centre. A placebo also does not facilitate randomisation, which can be done in single centre and multi-centre trials.

Upper brachial plexus roots innervate the proximal muscles of the shoulder and the upper arm. In this particular case, only these areas are affected, suggesting that the levels of brachial plexus injury are at roots C5-C6.

Macrosomia can be defined as either a birth weight greater than 4kg or birth weight greater than 90% for the gestational age. Risk factors for macrosomia include maternal diabetes, excessive gestational weight gain, pre-pregnancy obesity, male gender, ethnicity, and advanced gestational age. Genetic conditions associated with macrosomia are Bardet-Biedl syndrome, Perlman syndrome, Beckwith-Wiedemann syndrome, and Prader-Willi syndrome. Silver-Russell syndrome is associated with intrauterine growth retardation and post-natal failure to thrive.

Advancing paternal age has been linked with lower quality sperm leading to a reduction in overall fertility and an increase in the occurrence of various medical disorders in the fetus. Advanced paternal age has been implicated as a risk factor for diseases like retinoblastoma, achondroplasia, autism spectrum disorders, schizophrenia, and acute lymphoblastic leukaemia. Down’s syndrome is mostly considered a consequence of advanced maternal age, but advanced paternal age has also been implicated as a risk factor.

Epistaxis is common in younger children usually due to nose picking. After the episode is over no active management is required and reassurance should be given to the patient and his attendants.