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. It produces an itchy rash with a central area of clearance surrounded by raised scaly borders. Diagnosis can be made by skin examination. All other mentioned conditions do not affect the palms and soles.

Among the options provided, zidovudine causes lipoatrophy as a side effect.Zidovudine: Although both hypertrophy and atrophy are described related to HIV medications, nucleoside reverse transcriptase inhibitor (NRTIs) such as zidovudine and stavudine are closely associated with fat loss.Other options:- Enfuvirtide is an HIV-fusion inhibitor. Lipoatrophy is not commonly associated with this drug.- Efavirenz is an NNRTI, which is not associated with lipoatrophy. Common side effects include neuropsychiatric effects, rash and nausea. – Ganciclovir is not an anti-HIV medication and is used for cytomegalovirus (CMV) infections.- Raltegravir is an integrase inhibitor and is associated with fat gain.

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 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.

The clinical scenario provided is highly suggestive of third-degree burns (or full-thickness burns) that may have invaded the deeper levels up to dermis, evident from the insensate nature of the lesion.Degrees of Burns:- First degree burns are superficial second-degree burns.- Second-degree burns are just deeper than that of first-degree burns but vary enormously in other properties.- Third-degree burns are full-thickness burns which are leathery in consistency, and insensate. These burns do not heal on their own. The sensory neurons present in the skin at the deeper levels are destroyed completely and hence provide a paradoxical lack of pain.- Fourth-degree burns involving the subcutaneous tissues, tendons, and bones are very difficult to manage.Assessment of the extent of the burns for the treatment employs specialized charts, such as Lund and Browder charts and Wallace rule of nines.The Lund and Browder chart is, however, considered the most accurate.Wallace’s Rule of Nines can be used for children >16 years: – Head + neck = 9%- Each arm = 9%- Each anterior part of leg = 9%- Each posterior part of leg = 9%- Anterior chest = 9%- Posterior chest = 9%- Anterior abdomen = 9%- Posterior abdomen = 9%

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.

Haemolytic Uremic Syndrome affects children and is characterised by abdominal pain, a purpuric rash over the body, generalized pallor, haematuria and bloody diarrhoea. There is always a history of preceding diarrhoea caused usually by E.coli and it affects the renal system causing haematuria and deranged renal function tests.

Eight percentage of infantile haemangiomas are focal and solitary. Sixty percent of cutaneous haemangiomas occur on the head and neck, 25% on the trunk, and 15% on the extremities. Haemangiomas also can occur in extracutaneous sites, including the liver, gastrointestinal tract, larynx, CNS, pancreas, gall bladder, thymus, spleen, lymph nodes, lung, urinary bladder, and adrenal glands.Guidelines on the management of infantile haemangioma were released in December 2018 by the American Academy of Paediatrics stating that:Imaging is not necessary unless the diagnosis is uncertain, there are five or more cutaneous infantile haemangiomas present, or there is suspicion of anatomic abnormalities.

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.

Mild deficiencies of 21-hydroxylase or 3-beta-hydroxysteroid dehydrogenase activity may present in adolescence or adulthood with oligomenorrhea, hirsutism, and/or infertility. This is termed nonclassical adrenal hyperplasia.Late-onset or nonclassical congenital adrenal hyperplasia (NCAH) due to 21-hydroxylase deficiency is one of the most common autosomal recessive disorders. Reported prevalence ranges from 1 in 30 to 1 in 1000. Affected individuals typically present due to signs and symptoms of androgen excess. Treatment needs to be directed toward the symptoms. Goals of treatment include normal linear growth velocity, a normal rate of skeletal maturation, ‘on-time’ puberty, regular menstrual cycles, prevention of or limited progression of hirsutism and acne, and fertility. Treatment needs to be individualized and should not be initiated merely to decrease abnormally elevated hormone concentrations.Normal Ultrasound rules out Turner’s syndrome.

From the given scenario, the extraocular muscle affected in the child is superior oblique muscle. Point to remember:All of the extraocular muscles are supplied by the oculomotor nerve (3rd cranial nerve), except superior oblique (trochlear nerve/4th cranial nerve) and lateral rectus (abducens nerve/6th cranial nerve).The superior oblique muscle causes the eye to move downwards and medially. The unopposed inferior oblique, in this case, causes the eye to deviate upwards and medially. Children tend to tilt their head (torticollis) to the side opposite to the affected eye with their chin down toward the shoulder, and their face turned away from the affected side to decrease the diplopia.

Scurvy is a condition caused by a dietary deficiency of vitamin C, also known as ascorbic acid. Humans are unable to synthesize vitamin C, therefore the quantity of it that the body needs has to come from the diet. The presence of an adequate quantity of vitamin C is required for normal collagen synthesis. In scurvy bleeding tendency is due to capillary fragility and not coagulation defects, therefore blood tests are normal.

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.

Acoustic neuroma/vestibular schwannoma is a benign slow-growing tumour. The clinical picture of the child suggests neurofibromatosis type 1 (NF1), with cafe-au-lait spots and axillary and inguinal freckling.

Peutz-Jeghers syndrome is an autosomal dominant genetic disease. It presents with hyperpigmentation patches on the oral mucosa, lips, palm and soles, and nasal alae. It also presents with hamartomatous polyps in the gut, hence the fresh blood in this particular case.

An epidural hematoma occurs when there is bleeding between the dura mater (a tough fibrous layer of tissue between the brain and skull) and the skull bone. These occur when arteries are torn as a result of a blow to the head, and injury in the temple area is a common cause. Although the pattern of a lucid interval followed by later neurological symptoms is characteristic, only a minority of patients display this pattern of symptoms. Reported death rates from epidural hematoma vary widely, ranging from 5% to over 40%. Middle meningeal artery is frequently involved in such incidents.

Tuberous sclerosis is an autosomal dominant neurocutaneous condition associated with increased psychiatric co-morbidity. It results from the mutation of TSC1 or TSC2 tumour suppressor genes. Multiple benign tumours of the brain and other vital organs are characteristic of this disease. Important findings include subependymal nodules, bone cysts, cardiac rhabdomyoma, and learning difficulties. Lisch nodules of the iris occur in neurofibromatosis.

Diabetes insipidus (DI) is defined as the passage of large volumes (>3 L/24 hr) of dilute urine (< 300 mOsm/kg). It has the following 2 major forms:Central (neurogenic, pituitary, or neurohypophyseal) DI, characterized by decreased secretion of antidiuretic hormone (ADH| also referred to as arginine vasopressin [AVP])Nephrogenic DI, characterized by decreased ability to concentrate urine because of resistance to ADH action in the kidney.The boy most probably has nephrogenic diabetes insidious (DI) not central DI so he is not responding to the ADH treatment.

The boy is most likely to have sustained an injury to his brachial plexus as a result of upward traction of his arm for an extended period of time. We can rule out the topmost nerve roots of the brachial plexus, C6 and C7 as these supply the larger muscles of the arm responsible for moving the shoulder, the elbow and the wrist. The anatomical structure affected is therefore the T1 nerve root which is responsible for movement of the muscles in the hand. This type of injury is called a Klumpke’s Palsy, which is the result of a hyper-abducted trauma to the arm, damaging the C8 and T1 nerve roots. While the radial and ulnar nerve also innervate the hand, the history given points to Klumpke’s palsy as the best explanation for this mechanism of injury.

The clinical picture suggests intracranial haemorrhage which is uncommon but prevalent in pre-term babies. The rest of the options suggest peripheral causes which do not affect the central function.