In haemophilia C, The severity of the deficiency is based on plasma factor XIC (clotting) activity. Major factor XI deficiency is present when the activity of factor XI in plasma is less than 1-15 IU/dL.In major deficiency factor XI, bleeding is related to injury, especially when trauma involves tissues rich in fibrinolytic activators, such as the oral mucosa, the nose, and the urinary tract. Unlike patients with severe haemophilia A or B, patients with major factor XI deficiency do not spontaneously bleed.The aPTT is usually prolonged in factor XI deficiency (but depends on the sensitivity of the reagent and test system–partial deficiency can be missed), whereas the PT and TT are normal.

Haemophilia B (also known as Christmas disease) is due to a deficiency in factor IX. Haemophilia A is due to a deficiency in factor VIII.

The age of the patient and the presence of immature white blood cells are suggestive of leukaemia. Hodgkin’s disease is unlikely in this age group and it usually presents with lymphadenopathy. In HIV, immature white blood cells are not present in the blood.

Factors V and VIII are consumed most rapidly in a patient with disseminated intravascular coagulation.Simultaneous coagulation and haemorrhage caused by initially formation of thrombi which consume clotting factors (factors 5,8) and platelets, ultimately leading to bleeding.Causes include:- Infection- Malignancy- Trauma e.g. major surgery, burns, shock, dissecting aortic aneurysm- Liver disease- Obstetric complicationsClinically bleeding is usually a dominant feature, bruising, ischaemia and organ failure.Blood tests reveal prolonged clotting times, thrombocytopenia, decreased fibrinogen and increased fibrinogen degradation products.Treatment of DIC involves treating the underlying cause and supportive management.Mnemonic:D-I-S-S-E-M-I-N-A-T-E-DD- D dimerI-Immune complexesS-Snakebite, shock, heatstrokeS-SLEE-Eclampsia, HELLP syndromeM-Massive tissue damageI-Infections: viral and bacterialN-NeoplasmsA-Acute promyelocytic leukaemiaT-Tumour products: Tissue Factor (TF) and TF-like factors released by carcinomas of pancreas, prostate, lung,colon, stomachE-Endotoxins (bacterial)D-Dead foetus (retained)

The presentation of the child is highly suggestive of Henoch-Schonlein purpura (HSP). It is an IgA-mediated, autoimmune hypersensitivity vasculitis that targets the small vessels of the skin, GI tract, kidneys, and joints.It is most commonly seen in children aged 3 – 6 years old and is twice as common in boys than girls. Preceding viral URTI with low-grade pyrexia is common. The most common organism associated with HSP is, however, Group A streptococcal infection.A purpuric rash is seen on the back of the legs and buttocks and can less frequently affect the arms. Arthralgia is common (usually knees/ankles) in these patients.Abdominal pain and bloody diarrhoea may occur. And half of the children with HSP have renal involvement. Rarely, it can lead to end-stage renal failure.Treatment includes adequate hydration, occasionally steroids, and other immunosuppressants. The disease can recur in 1 in 3 children.

The diagnosis of a post-splenectomy/hyposplenism blood picture can be made reliably by identifying Howell Jolly bodies in routine Wright-Giemsa stained blood and target cells. These are round basophilic bodies in red blood cells that represent residual nuclear material from marrow nucleated red cell precursors that are usually culled out by the spleen.These do not occur in individuals with normally functioning splenic tissue and their presence indicates either 1) an asplenic state or 2) hypofunctioning splenic tissue as might be seen in a patient with late-stage sickle cell anaemia. Their presence in an individual with splenomegaly leads to a narrow differential diagnosis and their absence in a splenectomised individual indicates accessory splenic Heinz bodies and poikilocytosis typically increase in a splenectomised individual and care must be taken not to overdiagnose haemolysis in such an individual.

Transfusion with blood products carries a risk of acute and more chronic adverse reactions. These reactions can either be immune mediated due to a component mismatch, or non immune, underpinned by bacterial or viral contamination. Reactions range from very mild such as urticaria, to life threatening in the case of transfusion-related acute lung injury. In transfusion with packed red blood cells, the most common adverse event is pyrexia, while urticaria is the most common adverse event that follows infusion with FFP.

Hyposplenism is associated with thrombocytosis. Other features of hyposplenism are: – Howell-Jolly bodies and acanthocytosis, occurring secondary to haemolysis.- Pappenheimer bodies: These are granular deposits of iron found within the RBCs.- Lymphocytosis and monocytosis.Causes for hyposplenism include:- Congenital asplenia- Iatrogenic splenectomy: Following trauma or treatment for ITP, thalassemia or spherocytosis).- Autosplenectomy: Secondary to sickle cell anaemia, coeliac disease, dermatitis herpetiformis, essential thrombocythemia or splenic arterial thrombosis).

Lead can be found in material used for mining, leaded paints and gasoline, glassware, toys, and even cosmetics. Lead poisoning is rare nowadays as the use of lead has been banned from many products. Lead is toxic and in certain concentrations can cause irreversible damage. Children are especially vulnerable as they absorb 4 times as much ingested lead as adults. The typical features of lead poisoning include developmental delay and behavioural disorders, microcytic anaemia, constipation and vomiting. Pulmonary fibrosis, Osteomalacia and cardiomyopathy are not known features of lead poisoning.

Bone marrow failure syndromes are characterized by the bone marrow’s inability to produce cells of different lineage. They can be classified as those affecting one or two cell lineages or those affecting all three of them. Fanconi syndrome, along with dyskeratosis congenita, is one of the inherited bone marrow failure syndromes that causes pancytopenia. Other inherited disorders affecting hematopoietic lineage include Diamond-Blackfan anaemia, Schwachman-Diamond syndrome, congenital amegakaryocytic thrombocytopenia (CAMT) and Thrombocytopenia absent radii (TAR) syndrome. Acquired causes of bone marrow failure that lead to pancytopenia include aplastic anaemia, drugs, nutritional deficiencies, and viral infections. Kostmann syndrome is an autosomal recessive form of severe neutropenia, most likely due to excessive neutrophil apoptosis.