Patients with HIV have a deficiency of CD4 lymphocytes which are also known as helper T cells (Th). They are involved with antigen-specific responses as well as delayed-type hypersensitivity. The risk of developing P. jiroveci pneumonia is greatest with a CD4 count of 200 x 109/l or below.

The most probable diagnosis for this patient would be Crohn’s disease.Crohn’s disease:An inflammatory bowel disease which can affect any part of the bowel from the mouth to the anus. Symptoms include abdominal pain, diarrhoea, pyrexia and weight loss. Extra-intestinal manifestations include arthritis, uveitis, fatigue, anaemia and rashes including pyoderma gangrenosum and erythema nodosum.Other options:- Anorexia nervosa is an important diagnosis to consider. There are no indicators in the description that she has a fear of gaining weight or a strong desire to be thin.- Diabetic ketoacidosis is incorrect because there is no polydipsia or polyuria. A patient in DKA is more likely to present with vomiting and not diarrhoea.- Recurrent aphthous stomatitis is not a correct answer because it does not explain all of the symptoms described, only the mouth ulcers.- Ulcerative colitis (UC) is also incorrect. UC is a form of inflammatory bowel disease that causes inflammation in the colon. The main symptom is bloody stools, which is not mentioned as a feature in history.

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.

Neurofibromatosis (aka Von Recklinghausen’s disease) includes: neurofibrosarcomas, pheochromocytoma, optic nerve tumours, scoliosis and acoustic neuromas.

Low oxygen delivery in hypotension, hypoxia, oedema, intracranial hypertension or changes in cerebral blood flow should all be prevented to avoid secondary brain injury. There is no evidence to suggest that hypothermia prevents secondary brain injuries.

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.

Chickenpox is a highly communicable viral disease caused by human (alpha) herpesvirus 3 (varicella-zoster virus, VZV). It is transmitted from person to person by direct contact (touching the rash), droplet or air born spread (coughing and sneezing).

History of recurrent infections and failure to thrive (probably due to pancreatic enzyme insufficiency) is highly suggestive of cystic fibrosis. Pseudomonas has been identified as an important respiratory pathogen in patients with cystic fibrosis.

Based on the clinical scenario, the most probable diagnosis for this patient is maxillary sinusitis.The maxillary sinus drains from its superior aspect, leaving it prone to infections. It is the most commonly affected sinus in sinusitis.Common symptoms of maxillary sinusitis include postnasal discharge, pain, headache and toothache.Radiological imaging may show a fluid level in the antrum.Common organisms causing maxillary sinusitis include Haemophilus influenzae or Streptococcus pneumoniae.Treatment with antral lavage may facilitate diagnosis and relieve symptoms. Antimicrobial therapy has to be continued for long periods. Antrostomy may be needed.Other options:- Frontal sinusitis more commonly causes intracranial complications, but it is still less frequent than maxillary sinusitis.- The petrosal sinus is not a cavity within bone| rather, it is a venous structure located beneath the brain.- Frontoethmoidal sinusitis: It usually presents with frontal headache, nasal obstruction and altered sense of smell. Inflammation may progress to involve periorbital tissues. Ocular symptoms may occur, and secondary CNS involvement brought about by infection entering via emissary veins. CT scanning is the imaging modality of choice. Early cases may be managed with antibiotics. More severe cases usually require surgical drainage.

E. coli accounts for the majority of UTI’s in children. If this child responds well to treatment and has no recurrence of his symptoms, then no form of imaging is required, as per NICE advice for children aged 6 months to 3 years. Had the child been less than 6 months of age, then a USS at 6 weeks would be necessary.Other options:- Pseudomonas causes atypical UTI. This warrants ultrasonography within the acute illness phase as it may reflect an underlying pathology and DMSA at 4-6 months.- Recurrent UTI is defined as two or more episodes of pyelonephritis OR 1 pyelonephritis and one cystitis OR 3 or more cystitis. It requires USS at six weeks and DMSA at 4-6 months.- Septicaemia is a sign of an atypical UTI. This requires USS within the acute illness as it may reflect an underlying pathology and DMSA at 4-6 months.- Unwell 48hrs post antibiotics is a sign of an atypical UTI. This requires USS within the acute illness as may reflect underlying pathology and DMSA at 4-6 months.

Observational studies fall under the category of analytic study designs and are further sub-classified as observational or experimental study designs. The goal of analytic studies is to identify and evaluate causes or risk factors of diseases or health-related events. The differentiating characteristic between observational and experimental study designs is that in the latter, the presence or absence of undergoing an intervention defines the groups. By contrast, in an observational study, the investigator does not intervene and rather simply “observes” and assesses the strength of the relationship between an exposure and disease variable.Three types of observational studies include cohort studies, case-control studies, and cross-sectional studies. Case-control and cohort studies offer specific advantages by measuring disease occurrence and its association with an exposure by offering a temporal dimension (i.e. prospective or retrospective study design). Cross-sectional studies, also known as prevalence studies, examine the data on disease and exposure at one particular time point. Because the temporal relationship between disease occurrence and exposure cannot be established, cross-sectional studies cannot assess the cause and effect relationshipDisadvantage of Cohort study is Susceptible to selection bias.

Turner syndrome, a condition that affects only females, results when one of the X chromosomes (sex chromosomes) is missing or partially missing. Turner syndrome can cause a variety of medical and developmental problems, including short height, failure of the ovaries to develop and heart defects.Turner syndrome may be diagnosed before birth (prenatally), during infancy or in early childhood. Occasionally, in females with mild signs and symptoms of Turner syndrome, the diagnosis is delayed until the teen or young adult years.

HbA1c stands for glycated haemoglobin. In patients with haemolytic diseases associated with a shortened RBC survival, HbA1c levels can be unusually low despite controlled diabetes mellitus.These haemolytic diseases can include glucose-6-phosphate dehydrogenase deficiency and sickle cell anaemia.HbA1c:It is a measure of non-enzymatic glycation which occurs due to haemoglobin’s exposure to plasma glucose. As plasma glucose increases so does HbA1c.The level of HbA1c quantitively assesses the control of diabetes mellitus over the last 120 days (as this is the life span of a red blood cell).Haemoglobin type A is separated on cation exchange chromatographyOther subsections include HbA1O, HbA1a, HbA1b.According to the updated NICE recommendations (2015):The target level of HbA1c in children with T1DM is 48 mmol/mol (6.5%) or lower. It is monitored every three months. Better control is associated with fewer long term complications

Crossover trials are characterized by the switching of study participants throughout the treatment groups, keeping a random order of switching. This randomization is important to determine any carry-over effect of different treatment modalities. The benefit of this study is the evaluation of the efficacy of various short-term treatment options for the relief of chronic conditions. The washout period is small in this type of study. Crossover studies are more efficient than the parallel studies, but they should be used according to the treatment options and outcomes.

Fanconi syndrome is a rare disorder characterized by defective proximal renal tubular reabsorption, which leads to excessive excretion of potassium, phosphate, uric acid, bicarbonates, glucose, and certain amino acids in the urine. Loss of potassium in the urine leads to hypokalaemia, while the loss of phosphate may lead to hypophosphatemic rickets. The overall impact is the failure to thrive and growth retardation.

Human breast milk composition changes with the progressive age of the infant. Breastmilk produced for a preterm baby often has a higher caloric content than breastmilk for a term baby. After the production of colostrum in the first days of life, the milk continues to mature. by week 4-6 milk can be considered fully mature. The average calories found in mature breastmilk are about 70kcal/100ml

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.

Based on the clinical presentation, the pubic hair development is in Tanner stage 2.The Tanner stages for pubic hair are as follows:Stage 1 – pre-adolescentStage 2 – sparse hair that is long, slightly pigmented and downyStage 3 – hair spread over the junction of the pubes, darker and coarserStage 4 – adult-type hair, but the area covered is smaller than it is in an adult.Stage 5 – adult in quantity and type

Answer: Undertake a laparotomyIntussusception, which is defined as the telescoping or invagination of a proximal portion of intestine (intussusceptum) into a more distal portion (intussuscipiens), is one of the most common causes of bowel obstruction in infants and toddlers.Intussusception may be ileoileal, colocolic, ileoileocolic, or ileocolic (the most common type).Most infants with intussusception have a history of intermittent severe cramping or colicky abdominal pain, occurring every 5-30 minutes. During these attacks, the infant screams and flexes at the waist, draws the legs up to the abdomen, and may appear pale. These episodes may last for only a few seconds and are separated by periods of calm normal appearance and activity. However, some infants become quite lethargic and somnolent between attacks.Infants with intussusception require surgical correction. Prompt laparotomy following diagnosis is crucial for achieving better outcomes. Primary anastomosis can be performed successfully, and stomas can be created in the critically ill patients or those with late detection and septicaemia.

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).

Breast milk jaundice is a type of jaundice associated with breast-feeding. It typically occurs one week after birth. The condition can sometimes last up to 12 weeks, but it rarely causes complications in healthy, breast-fed infants. The exact cause of breast milk jaundice isn’t known. However, it may be linked to a substance in the breast milk that prevents certain proteins in the infant’s liver from breaking down bilirubin. The condition may also run in families. Breast milk jaundice is rare, affecting less than 3 percent of infants. When it does occur, it usually doesn’t cause any problems and eventually goes away on its own. It’s safe to continue breast-feeding.

A periosteal reaction can result from a large number of causes, including injury and chronic irritation due to a medical condition such as hypertrophic osteopathy, bone healing in response to fracture, chronic stress injuries, subperiosteal hematomas, osteomyelitis, and cancer of the bone. This history is consistent with a toddler’s fracture. Here a minor, usually twisting, injury results in a spiral fracture of the tibia. An initial X-ray may appear normal as the periosteum holds the bone together preventing displacement. Ten days later a repeat X-ray will show callous formation and confirm the diagnosis.

The differentiation between type 1 and type 2 epithelia in the developing lung buds is evident from 16-24 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. – 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.

This girl most probably has Turner’s syndrome, which is caused by the absence of one set of genes from the short arm of one X chromosome.Turner syndrome is a lifelong condition and needs lifelong oestrogen replacement therapy. Oestrogen is usually started at age 12-15 years. Treatment can be started with continuous low-dose oestrogens. These can be cycled in a 3-weeks on, 1-week off regimen after 6-18 months| progestin can be added later.In childhood, growth hormone therapy is standard to prevent short stature as an adult.Fetal ovarian development seems to be normal in Turner syndrome, with degeneration occurring in most cases around the time of birth so pulsatile GnRH and luteinising hormone would be of no use.

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.

Pupils are dilated in patients with amitriptyline overdose.Tricyclic antidepressants have a narrow therapeutic index, and thus, small doses can be fatal in children. Deaths from tricyclics are more common than other antidepressants. Bimodal incidence with toddlers (accidental) and teenagers (deliberate) most commonly affected.Symptoms: They occur within 6 hours of ingestion.- Nausea, vomiting, and headache- Elevated body temperature- Agitation, sleepiness, confusion, coma- Dry mouth, blurred vision, urinary retention (anticholinergic)- Dilated pupils- Seizures- Hypotension, tachycardia, conduction disorders, and cardiac arrest- Respiratory depressionManagement:Treatment focuses on supportive care. This includes airway protection, ventilation and oxygenation, intravenous fluids, and cardiac monitoring.Other measures include:- Activated charcoal within 2 hours- Hypotension is treated with IV fluids and adrenaline- Cardiac monitoring- Sodium bicarbonate in acidosis or if there are wide QRS complex (> 100 ms)- Convulsions may require diazepam or lorazepam.

Alopecia areata is seen in 6-8.8% of patients with Down syndrome, but only 0.1% of patients with alopecia areata have Down syndrome. The high frequency of alopecia areata in patients with Down syndrome suggests that a genetic linkage for alopecia areata may exist on chromosome 21.

The inferior alveolar nerve supplies all the teeth of the respective hemimandible. It transverses the inferior alveolar canal and is a branch of the trigeminal nerve’s mandibular division. Therefore, in this case, the teeth of the right hemimandible will be numb.

Prednisone is used for the treatment of myasthenia gravis if there is no initial response to the anticholinesterase medications. Pyridostigmine can make the symptoms of myasthenia gravis worse if used  in the initial stages of treatment. 

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common enzyme deficiency in humans.It has a high prevalence in persons of African, Asian, and Mediterranean descent. It is inherited as an X-linked recessive disorder.G6PD deficiency is polymorphic, with more than 300 variantsG6PD deficiency can present as neonatal hyperbilirubinemia. Besides, persons with this disorder can experience episodes of brisk haemolysis after ingesting fava beans or being exposed to certain infections or drugs. Less commonly, they may have chronic haemolysis. However, many individuals with G6PD deficiency are asymptomatic.Most individuals with G6PD deficiency do not need treatment. However, they should be taught to avoid drugs and chemicals that can cause oxidant stress. Infants with prolonged neonatal jaundice as a result of G6PD deficiency should receive phototherapy with a bili light.