Pellagra occurs as a result of niacin (vitamin B-3) deficiency. Niacin is required for most cellular processes. Since tryptophan in the diet can be converted to niacin in the body, both of these need to be deficient for pellagra to develop.

The classical triad of symptoms is diarrhoea, dermatitis and dementia.

The first sign is reddened skin with superficial scaling in areas exposed to sunlight, heat and friction. This may resemble severe sunburn then gradually subsides leaving a dusky brown-red colouration. The rash is usually symmetrical with a clear edge between affected and unaffected skin.

According to the NICE guidelines, the frequency of stool passage is considered constipation when two or more of the following findings are present:

Fewer than 3 stools a week, large hard stools, stools that resemble rabbit droppings; symptoms associated with defecation including distress, bleeding or straining; a history of previous episodes of a precious/current anal fissure.

The child in the scenario fails to meet the criteria, and has no evidence of impacted faeces on examination. The best course of action is to encourage the parents to give the child more water to prevent dehydration, and feed the child a fibre rich diet including fruits, vegetables and high fibre bread.

In pyloric stenosis a new-born baby presents with a history of vomiting, constipation and deranged electrolytes. Excessive vomiting leads to hypokalaemia. Difficulty in food passing from the stomach to the small intestine causes constipation. Hypokalaemia also causes constipation. None of the other disorders mentioned present with the hypokalaemia, vomiting and constipation triad in a new-born.

Based on the clinical scenario, the most probable diagnosis for this patient is pancreatitis.
Although rare in childhood, the presence of abdominal pain radiating to the back with shock and tachycardia, and a raised amylase, should raise a suspicion of pancreatitis.
Possible causes include trauma, drugs, viral illness, mumps, hyperparathyroidism, hyperlipidaemia and cystic fibrosis.

Other options:
– Normal LFTs in this patient make hepatitis unlikely.
– Gastroenteritis with severe diarrhoea and vomiting may account for the shock and tachycardia, but guarding on abdominal examination and the raised amylase would not be explained by gastroenteritis.
– Pregnancy is an important diagnosis to consider in an adolescent with abdominal pain, but the raised amylase and other features point to a diagnosis of pancreatitis.

The Green Book guidelines report in an active infection (HBeAg+ and HBsAg+) to give the vaccine as well as immunoglobulin. If antibodies are present it is not active infection (anti-Hbe) and then in that case only the vaccine, and no immunoglobulin, would be given. The presence of HBeAg means a person is infectious and can transmit to other people.

Children are very prone to dehydration during an episode of gastroenteritis. Dehydration is detected early by increased capillary filling time.

The elemental diet is a medically supervised, sole nutrition dietary management given to individuals with moderate to severe impaired gastrointestinal function for 14-21 days.

The diet consists of macronutrients broken down into their elemental form requiring little to no digestive functionality allowing time for the gut to rest. Elemental formulations are believed to be entirely absorbed within the first few feet of small intestine.

Bulimia nervosa is a condition in which a person is involved in binge eating and then purging. This patient has swollen parotid glands. The glands swell in order to increase saliva production so that the saliva lost in the vomiting is compensated. This patient also has thickened calluses on the back of her hand. This is known as Russell’s sign. This occurs because of putting fingers in the mouth again and again to induce the gag reflex and vomit. The knuckles get inflamed in the process after coming in contact with the teeth multiple times.

The gastrocolic reflex is a physiological reflex that involves increase in colonic motility in response to stretch in the stomach and by-products of digestion in the small intestine. It is shown to be uneven in its distribution throughout the colon, with the sigmoid colon affected more than the right side of the colon in terms of a phasic response. Various neuropeptides have been proposed as mediators of this reflex, such as serotonin, neurotensin, cholecystokinin and gastrin.

Maternal smoking is one of the most significant risk factors for pyloric stenosis.

Remember the three Ps for Pyloric Stenosis:
P -palpable mass
P -peristalsis
P -projectile vomiting

The most likely causative organism for the symptoms of this child is Giardia lamblia.

Giardiasis results in fat malabsorption thus giving rise to greasy stools. It is resistant to chlorination, hence has a risk of transfer in swimming pools.

World Health Organisation definitions
– Diarrhoea: > 3 loose or watery stool per day
– Acute diarrhoea < 14 days
– Chronic diarrhoea > 14 days

Conditions that usually present as acute diarrhoea:
– Gastroenteritis: It may be accompanied by abdominal pain or nausea/vomiting.
– Antibiotic therapy: Can occur following antibiotic therapy, especially common with broad spectrum antibiotics.

Conditions that usually present as chronic diarrhoea:
– Irritable bowel syndrome: It is a very common disease.
The most consistent features are abdominal pain, bloating and change in bowel habit. Patients may be divided into those with diarrhoea predominant IBS and those with constipation-predominant IBS.
Features such as lethargy, nausea, backache and bladder symptoms may also be present in these patients.
– Ulcerative colitis: It presents as bloody diarrhoea. Patients can also present with crampy abdominal pain and weight loss. Faecal urgency and tenesmus may be seen.
– Crohn’s disease: It is also associated with crampy abdominal pains and diarrhoea. Bloody diarrhoea less common than in ulcerative colitis. Other features include malabsorption, mouth ulcers perianal disease and intestinal obstruction
– Colorectal cancer: It is very rare in children. The symptoms depend on the site of the lesion but include diarrhoea, rectal bleeding, anaemia and constitutional symptoms like weight loss and anorexia.
– Coeliac disease: In children, it may present with failure to thrive, diarrhoea and abdominal distension.

Other conditions associated with diarrhoea include thyrotoxicosis, laxative abuse, appendicitis, and radiation enteritis.

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

The signs and symptoms of vitamin D-dependent rickets begin within months after birth, and most are the same for all types of the condition. The weak bones often cause bone pain and delayed growth and have a tendency to fracture. When affected children begin to walk, they may develop abnormally curved (bowed) legs because the bones are too weak to bear weight. Impaired bone development also results in widening of the metaphysis, especially in the knees, wrists, and ribs. Some people with vitamin D-dependent rickets have dental abnormalities such as thin tooth enamel and frequent cavities. Poor muscle tone (hypotonia) and muscle weakness are also common in this condition, and some affected individuals develop seizures.

The baby has duodenal atresia.
Presenting symptoms and signs are results of high intestinal obstruction. Duodenal atresia is typically characterized by the onset of vomiting within hours of birth. While vomitus is most often bilious, it may be nonbilious because 15% of defects occur proximal to the ampulla of Vater. Occasionally, infants with duodenal stenosis escape detection of an abnormality and proceed into childhood or, rarely, into adulthood before a partial obstruction is noted. Nevertheless, one should assume any child with bilious vomiting has a proximal GI obstruction until proven otherwise, and further workup should be begun expeditiously.
congenital duodenal atresia is one of the more common intestinal anomalies treated by paediatric surgeons, occurring 1 in 2500-5000 live births. In 25-40% of cases, the anomaly is encountered in an infant with trisomy 21 (Down syndrome).

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.

The clinical picture suggests that the child is severely dehydrated. IV fluid bolus then IV maintenance fluids is the correct option.

Peutz-Jeghers syndrome (PJS) is an autosomal dominant inherited disorder characterized by intestinal hamartomatous polyps in association with a distinct pattern of skin and mucosal macular melanin deposition (freckles on the lips, face, palms and soles). Patients with Peutz-Jeghers syndrome have an estimated 15-fold increased risk of developing intestinal cancer compared to the general population.

Management: conservative unless complications develop.

Pale, bulky, malodorous stools are evidence of fat malabsorption syndrome. The diagnostic test is jejunal biopsy to rule out other differential diagnoses such as celiac disease, giardiasis or Crohn’s disease etc.

Breast feeding should be continued for babies with breast milk jaundice as this is a benign condition.

Most experts suggest that parents reassurance in case of infantile gastro-oesophageal reflux (GOR) is a sufficient initial measure that involves education about regurgitation and lifestyle changes.

Based on the clinical scenario, the most likely risk factor in this child to develop gallstones is sickle cell disease.

Note:
Haemolysis is the most frequent cause for gallstones in children and the likeliest cause because of his ethnicity would be sickle cell disease. The gallstones are pigmented which form from bilirubin. 70% of patients with sickle cell disease will develop gallstones; the prevalence of gallstones is related to the rate of haemolysis.

Other options:
– Gilbert’s syndrome: it is a common condition in which bilirubin glucuronidation (i.e. converting bilirubin into a water-soluble form) is affected. During times of stress (viral illness, fasting, etc.) there is an excess bilirubin production, and jaundice may develop. It is a benign condition but there is some evidence of an increased risk of developing gallstones. However, sickle cell disease is a more likely risk factor in this case.
– Hereditary spherocytosis: Hereditary spherocytosis is a disease of the white population and is less likely to be the underlying cause in this case.
– Male gender: After puberty, the incidence of gallstones is higher in women. Before puberty, the incidence is equal.
– Obesity: Obesity is a risk factor for gallstones and is thought to be behind the rising incidence among young adults. Nevertheless, haemolytic states remain the most common reason for gallstones in children.

Based on the given scenario, the most probable diagnosis for this patient is acquired immune deficiency syndrome (AIDS) caused by human immunodeficiency virus (HIV). Thus, the most appropriate investigation to confirm the underlying pathology in this patient would be viral serology.

Rationale:
The presence of oesophageal candidiasis is highly suggestive of severe immunosuppression. The causes of immunosuppression can be chemotherapy, with haematological malignancy, HIV or inhaled steroids.
In patients with HIV, oesophageal candidiasis is part of the spectrum of AIDS-defining illnesses and usually occurs when the CD4 count is < 200 cells/microL. Other AIDS-defining illnesses include PCP pneumonia and CMV infections. Oesophageal Candidiasis:
It is characterised by white spots in the oropharynx with extension into the oesophagus. It seldom occurs without an associated underlying risk factor like broad-spectrum antibiotic usage, immunosuppression and immunological disorders.
Patients may present with oropharyngeal symptoms, odynophagia and dysphagia.
Treatment is directed both at the underlying cause (which should be investigated for) and with oral antifungal agents.

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.

Meckel’s diverticulum is a congenital diverticulum of the small intestine. It is a remnant of the omphalomesenteric duct (also called the vitellointestinal duct) and contains ectopic ileal, gastric or pancreatic mucosa.

Rule of 2’s
– occurs in 2% of the population
– it is located 2 feet proximal to the ileocaecal valve
– it is 2 inches long
– it is 2 times more common in men
– there are 2 tissue types involved

It is typically asymptomatic. Symptomatic presentation indicates inflammation of the diverticulum. The symptoms include:
– Abdominal pain mimicking appendicitis
– Rectal bleeding
– Intestinal obstruction: secondary to an omphalomesenteric band (most commonly), volvulus and intussusception

Management:
Surgical removal if the neck of the diverticulum is narrow or symptomatic. Surgical options are excision or formal small bowel resection and anastomosis.

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.

The structure in question is the rectus sheath. This sheath encloses the rectus abdominis muscle and thus, will be encountered by the surgeon.

Note:
– Midline incision: It is the most common approach to the abdomen. The
structures divided during this incision are linea alba, transversalis fascia, extraperitoneal fat, and peritoneum ( with care taken to avoid the falciform ligament above the umbilicus).
The bladder can be accessed via an extraperitoneal approach through the space of Retzius.
– Paramedian incision: It is an incision that is made parallel to the midline. The structures divided or retracted are anterior rectus sheath, rectus (retracted), posterior rectus sheath, transversalis fascia, extraperitoneal fat, and peritoneum.
– Battle incision: It is similar to a paramedian but the rectus is displaced medially (and thus denervated).
– Kocher’s incision: It is an incision made under the right subcostal margin, e.g. cholecystectomy (open).
– Lanz incision: It is an incision in the right iliac fossa, e.g. appendicectomy.
Gridiron incision: It is an oblique incision centred over the McBurney’s point – usually used for appendicectomy (less cosmetically acceptable than Lanz
Pfannenstiel’s incision: It is a transverse suprapubic incision, primarily used to access pelvic organs.
McEvedy’s incision: It is a groin incision used for emergency repair strangulated femoral hernia.
Rutherford Morrison incision: It provides an extraperitoneal approach to left or right lower quadrants. It provides excellent access to iliac vessels and is the approach of choice for first-time renal transplantation.

Laxatives have been shown to be beneficial in the treatment of chronic childhood constipation. Studies have shown that polyethylene glycol, mineral oil, magnesium hydroxide, and lactulose are effective and can be used for a prolonged periods without risk.

Celiac disease is classified as a Type IV hypersensitivity mediated by T-cell response. Negatively charged gliadin has been shown to induce interleukin 15 in the enteric epithelial cells, stimulating the proliferation of the natural killer cells and intraepithelial lymphocytes to express NK-G2D, a marker for natural killer T lymphocytes.

Celiac disease has characteristic shortened intestinal villi. When patients with celiac disease eat products containing gluten, they are unable to absorb the nutrients due to flattened or shortened intestinal villi. The blistering rash present on the patient’s elbows strongly suggests celiac disease. This rash is a sign of the condition Dermatitis Herpetiformis which is associate with celiac disease. Therefore, it is also often called ‘gluten rash’.

Biliary atresia is a rare condition that usually becomes symptomatic 2 to 8 weeks after birth. It can be congenital or acquired. Typical symptoms include jaundice, weight loss, dark urine and pale stools.