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.

The clinical presentation of lichen planus has several variations, as follows:- Hypertrophic lichen planus- Atrophic lichen planus- Erosive/ulcerative lichen planus- Follicular lichen planus (lichen planopilaris)- Annular lichen planus- Linear lichen planus- Vesicular and bullous lichen planus- Actinic lichen planus- Lichen planus pigmentosus- Lichen planus pemphigoides

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.

H. pylori release the enzyme urease that has the ability to split urea releasing nitrogen. This process increases the pH in the gastric antrum making the gastric pH less acidic.Helicobacter pylori:It is a spiral, microaerophilic, gram-negative bacterium. It is one of the most common causes of antral gastritis in children. Ulcers are less common in children compared with adults| however, when they occur, they are more common in the duodenum.The presence of H.pylori can be confirmed by:- Stool antigen test (preferred)- Serology- Endoscopy with biopsy and culture- Rapid urease testsH.pylori gastritis may be associated with:- Iron deficiency anaemia- Gastric malignancy Management:The treatment is with triple therapy- two antibiotics, and an antacid.Treatment failure is often attributed to a possible worldwide increase in macrolide resistance. Interestingly, children have higher antibiotic resistance compared with adults.Note:Zollinger-Ellison syndrome (ZES) causes gastrin-secreting tumours and can present as a part of multiple endocrine neoplasia type 1 (MEN1)- an autosomal dominant disorder.

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.

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.

While the clinical scenario and the anosmic presentation of the child are highly suggestive of Kallmann’s syndrome, reduced testosterone, FSH and LH levels can confirm the diagnosis.Kallman’s syndrome is a recognised cause of delayed puberty secondary to hypogonadotropic hypogonadism. It is usually inherited as an X-linked recessive trait. Kallman’s syndrome is thought to be caused by a failure of GnRH-secreting neurons to migrate to the hypothalamus.Clinical features of Kallmann’s syndrome include:- Delayed puberty- Hypogonadism, cryptorchidism- Anosmia- Low sex hormone levels – Inappropriately low/normal LH and FSH levels- Some patients can present with associated cleft lip/palate and visual/hearing defects.

Intrauterine growth restriction refers to the failure of the fetus to grow in accordance with the weeks of gestation. There are two types of growth restriction, symmetrical and asymmetrical. Causes include various genetic abnormalities, fetal infections, maternal health conditions, etc. Risk factors for the development of IUGR include fetal echogenic bowel, maternal age above 40 years, low PAPP-A levels, maternal smoking or cocaine use, etc. Fetal echogenic bowel implies a brighter than usual fetal intestines on ultrasonography. It is a marker associated with trisomy 21, which is a cause of IUGR.

The incubation periods of disorders is extremely important to diagnose, treat, prevent or attenuate a disease. Chickenpox: 7-21 days. Whooping cough: 10-14 days. Hand, foot and mouth disease: 2-6 days. German measles: 14-21 days. Mumps: 14-18 days.

The most probable diagnosis in this patient would be hyphaema.The acuity has varied because the blood has been settling in the anterior chamber of the eye, thus allowing a reasonable level of visual acuity. The size of the tennis ball (which is not as harmful as a squash ball in the eye) and the fact that it was struck from a distance would cause a moderately significant injury due to pressure to the globe. Other options:- The absence of severe pain makes a large corneal abrasion less likely. – Vitreous haemorrhage would lead to very poor acuity, more likely ‘hand movements only’. – A retinal detachment or traumatic cataract would not produce such immediate symptoms, and if they did occur it would probably be in the presence of more extensive eye trauma and pain, with additional signs of both hyphaema and vitreous haemorrhage.

People with Gilbert syndrome have a build-up of unconjugated bilirubin in their blood (unconjugated hyperbilirubinemia). In affected individuals, bilirubin levels fluctuate and very rarely increase to levels that cause jaundice. Gilbert syndrome is usually recognized in adolescence. If people with this condition have episodes of hyperbilirubinemia, these episodes are generally mild and typically occur when the body is under stress, for instance because of dehydration, prolonged periods without food (fasting), illness, vigorous exercise, or menstruation. Some people with Gilbert syndrome also experience abdominal discomfort or tiredness. However, approximately 30 percent of people with Gilbert syndrome have no signs or symptoms of the condition and are discovered only when routine blood tests reveal elevated unconjugated bilirubin levels.

On electrocardiography (ECG), characteristic changes in patients with hypercalcemia include:Tall T wavesReduced QTProlonged and depressed STArrhythmiaOther electrolyte disturbances:Hypokalaemia:Flat T wavesST depressionU waveAtrial and ventricular ectopicsVF and VTHyperkalaemia:Tall T wavesST- changesReduced QT intervalIncreased PR intervalSmaller or absent P wavesWidened QRS, broadening to VFHypocalcaemia:Prolonged QTProlonged STFlat or absent T wavesU waves

Erythema nodosum (EN) is an acute, nodular, erythematous eruption that usually is limited to the extensor aspects of the lower legs. It is a delayed hypersensitivity reaction to a variety of antigens| circulating immune complexes have not been found in idiopathic or uncomplicated cases but may be demonstrated in patients with inflammatory bowel disease.Currently, the most common cause of erythema nodosum is a streptococcal infection in children and streptococcal infection and sarcoidosis in adultsIn most patients, erythema nodosum is a self-limited disease and requires only symptomatic relief using nonsteroidal anti-inflammatory drugs (NSAIDs), cool wet compresses, elevation, and bed rest.

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.

Urine culture and sensitivity is used to diagnose a urinary tract infection (UTI). A mid-stream clean catch urine sample is the most common type of sample collected. It is important to follow the clean catch process to have accurate results from an uncontaminated sample. Urine cultures can also check for infections of the bladder or kidney.

The injury described in question leads to an abnormal communication between the orbit and the ipsilateral maxillary sinus – this is termed as a blow-out fracture of the orbit.The maxillary sinuses are found in the maxillary bone, inferior to the orbit. They are the largest of the paranasal air sinuses. The maxillary bone forms the floor of the orbit. This layer of bone separates the orbit from the maxillary sinus. As such, fractures of the floor of the orbit can be associated with herniation of the orbital contents into the maxillary sinus. Other options:- The ethmoidal air cells are a collection of smaller air cells in the ethmoid bone. They lie lateral to the anterior superior nasal cavity. They are separated from the orbit by a very thin plate of ethmoid bone called the lamina papyracea, which is found on the medial wall of the orbit. The thin nature of this bone means it is commonly fractured in orbital trauma. However, this is the incorrect answer to the above question as a communication between the ethmoidal air cells, and the orbit is associated with fractures of the medial wall of the orbit, not the floor. – The frontal sinuses are found in the frontal bones, above the orbits on each side of the head. A large portion of the roof of the orbit is composed of the frontal bone and separates the orbit from the frontal sinus. Fractures of the roof of the orbit can be associated with communication between the frontal sinus and orbit. The frontal bones are strong, and so fracture is associated with high-impact anterior trauma, such as a road traffic accident. – The sphenoid sinuses are found in the posterior portion of the roof of the nasal cavity. The pituitary gland lies nestled within the hypophyseal fossa, with only a thin wall of bone separating it from the sphenoid sinus below. As such, neurosurgeons can gain access to the pituitary gland via the sphenoid sinus, in a procedure called transsphenoidal hypophysectomy. – The nasal cavity extends from the nares to the nasopharynx. It is found more medial and inferior than the orbits. It does not lie adjacent to the orbit at any point and so is unlikely to be involved in an orbital fracture.

Developmental milestones at the age of 2 months are as follows:Social and Emotional:- Begins to smile at people – Can briefly calm herself (may bring hands to mouth and suck on hand)- Tries to look at the parents Language/Communication:- Coos, makes gurgling sounds – Turns head toward sounds Cognitive (learning, thinking, problem-solving):- Pays attention to faces – Begins to follow things with eyes and recognize people at a distance – Begins to act bored (cries, fussy) if an activity doesn’t changeMovement/Physical Development:- Can hold head up and begins to push up when lying on tummy – Makes smoother movements with arms and legs

The vignette describes an infant with a sustained post-delivery brachial plexus injury that does not improve with time. MRI is the most appropriate intervention to assess the injury and evaluate the treatment options.

Rett syndrome is a disorder that affects the brain and occurs most commonly in girls. It presents with a period of normal development followed by severe problems with language and communication, learning, coordination, and other brain functions.

Certain lesions present on x-ray are suggestive of child abuse including rib, humerus and skull fractures. It is the doctors responsibility to follow up on these cases to determine whether domestic abuse has occurred.

Klinefelter syndrome is a sex chromosome disorder in boys and men that results from the presence of an extra X chromosome in cells. People typically have 46 chromosomes in each cell, two of which are the sex chromosomes. Females have two X chromosomes (46,XX), and males have one X and one Y chromosome (46,XY). Most often, boys and men with Klinefelter syndrome have the usual X and Y chromosomes, plus one extra X chromosome, for a total of 47 chromosomes (47,XXY).Cri-du-chat (cat’s cry) syndrome, also known as 5p- (5p minus) syndrome, is a chromosomal condition that results when a piece of chromosome 5 is missing.Pierre Robin syndrome is not caused by a single gene defect but is a sequence.Meningomyelocele does not follow usual patterns of inheritance.

Intussusception causes abdominal pain leading to painful lower GI bleeding. Intussusception is a condition in which part of the intestine folds into the section next to it. It most commonly involves the small bowel and rarely the large bowel. Intussusception doesn’t usually require surgical correction. 80% of cases can be both confirmed and reduced using barium, water-soluble or air-contrast enema.However, up to 10% of cases can experience recurrence within 24 hours after reduction, warranting close monitoring during this period.Most children have self-limiting and minor bleeds. However, children with massive bleeds will need emergency care and stabilisation.The various causes of lower GI bleeding in neonates include:- Anal fissures- Milk protein or soy allergy- Intussusception- Volvulus- Coagulopathies including haemorrhagic disease of the new-born- Arteriovenous malformations- Necrotising enterocolitis- Hirschsprung enterocolitis- Meckel’s diverticulitis- Drugs (NSAIDs, heparin, indomethacin used for patent duct closure, dexamethasone)The various causes of lower GI bleeding in children aged between 1 month to 2 years include:- Infection- Anal fissures- Intussusception- Malrotation with volvulus- Milk protein or soy allergy- Polyp- Meckel’s diverticulum- Duplication cyst- Foreign body- AV malformation- Colitis of immune deficiency- Tumour- HaematomaThe causes of lower GI bleeding in children older than 2 years include:- Polyp- Inflammatory bowel disease (IBD)- Infectious diarrhoea (caused by Escherichia coli and Shigella)- Intussusception- Haemangiomas- Arteriovenous malformations- Vasculitis- Tumour

Congenital TB symptoms typically develop during the second or third week of life and include poor feeding, poor weight gain, cough, lethargy, and irritability. Other symptoms include fever, ear discharge, and skin lesions.Signs of congenital TB include failure to thrive, icterus, hepatosplenomegaly, tachypnoea, and lymphadenopathy.

In the pattern of mendelian inheritance, X- linked dominant inheritance means that all who inherit the X chromosome will present with the condition. In the case of maternal x-linked inheritance sons and daughters have an equal chance of inheriting the condition as there is a 50% chance of inheriting the defective X chromosome from their mother as opposed to a non affected X chromosome from their father. However in paternal X-linked dominant inheritance, sons will be unaffected as they inherit a Y chromosome from their father while daughters are sure to inherit the defective X-chromosome.

The child has nephrotic syndrome which is most commonly caused by minimal change nephropathy in this age group. The condition presents with fusion of foot processes of the glomerular epithelial cells under the microscope.

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.

Impetigo appears more commonly on the face than other exposed areas like the limbs. Its blisters are clustered and may have a fluid discharge.

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.

One of the most common congenital viral infections is cytomegalovirus infection. The infection is even commoner than the other widely known diseases like down’s syndrome and spina bifida. It is caused by herpesvirus type 5 and is diagnosed using PCR of saliva. The clinical features include failure to thrive, intellectual disability, epilepsy, and microcephaly. The most common clinical complication is sensorineural deafness. The drug of choice for the treatment of neonatal CMV infection is ganciclovir, an anti-viral drug that has shown to prevent deafness. Cytomegalic inclusion disease is diagnosed at birth with marked neurological disability, resulting from microcephaly, intracerebral calcifications, and cerebral atrophy.

Renal stones < 5mm generally pass spontaneously with adequate fluid intake. Stones 5mm-10mm with pain not resolving, require medical expulsive therapy with Nifedipine or Tamsulosin. For stones larger than 10mm, ESWL or Ureteroscopy is indicated. For stones as big as 2cm, percutaneous nephrolithotomy should be applied.