Due to breakdown of the red blood cell membrane in haemophilic patients, cholesterol crystals are formed by the lipids. On the other hand lipofuscin deposition does not occur in haemolysis or haemorrhage. Neutrophil accumulation suggests acute inflammation. Anthracotic pigment is an exogenous carbon pigment that deposits in the lung from dust. Russell bodies are intracellular accumulations of immunoglobins in plasma cells. Curschmann’s spirals and Charcot Leyden crystals are pathognomonic of asthma.

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 child is suffering from acute sickle cell crisis, a complication of sickle cell disease. It is characterised by a new segmental pulmonary infiltrate consistent with consolidation together with one or more new respiratory symptoms.The mainstay of treatment is oxygen support, (ventilation if required), hydration, antibiotics and analgesia.

A peripheral blood film in iron deficiency anaemia can reveal the following morphologically variant RBCs:- Microcytic cells- Hypochromic cells- Pencil cells- Target cellsOther options:- Schistocytes can be caused by mechanical heart valves. – Rouleaux can be seen in chronic liver disease and malignant lymphoma. – Tear-drop poikilocytes can be seen in myelofibrosis. – Acanthocytes can be seen in liver disease and McLeod blood group phenotype.Pathological red cell forms include:- Target cells: Sickle-cell/thalassaemia, iron-deficiency anaemia, hyposplenism, and liver disease.- Tear-drop poikilocytes: Myelofibrosis- Spherocytes: Hereditary spherocytosis and autoimmune haemolytic anaemia- Basophilic stippling: Lead poisoning, thalassaemia, sideroblastic anaemia, and myelodysplasia- Howell-Jolly bodies: Hyposplenism- Heinz bodies: G6PD deficiency and alpha-thalassaemiaSchistocytes (‘helmet cells’): Intravascular haemolysis, mechanical heart valve, and disseminated intravascular coagulation- Pencil poikilocytes: Iron deficiency anaemia- Burr cells (echinocytes): Uraemia and pyruvate kinase deficiency – Acanthocytes: Abetalipoproteinemia

Von Willebrand disease (VWD), a congenital bleeding disorder caused by deficient or defective plasma von Willebrand factor (VWF), may only become apparent on haemostatic challenge, and bleeding history may become more apparent with increasing age. Type 1 VWD (,30% of VWD) typically manifests as mild mucocutaneous bleeding. Type 2 VWD accounts for approximately 60% of VWD. Type 2 subtypes include: Type 2A, which usually manifests as mild-to-moderate mucocutaneous bleeding| Type 2B, which typically manifests as mild-to-moderate mucocutaneous bleeding that can include thrombocytopenia that worsens in certain circumstances| Type 2M, which typically manifests as mild-moderate mucocutaneous bleeding| Type 2N, which can manifest as excessive bleeding with surgery and mimics mild haemophilia A. Type 3 VWD (<10% of VWD) manifests with severe mucocutaneous and musculoskeletal bleeding.

Red blood cells (RBC) have a life span of 120 days in humans.Aging of RBC includes changes in many properties: decreased metabolic activity, morphological alterations, including decreased cell volume and changes in cell shape, and quantitative and qualitative modulations of the surface.

Non-Hodgkin Lymphoma: The history is of enlarged reticuloendothelial system with abnormalities in all 3 cell lines of the bone marrow (pallor, fever and petechiae). The most likely diagnosis is therefore acute (lymphoblastic) leukaemia. Lymphadenopathy may be prominent: mediastinal nodes are characteristic of T-cell leukaemia. In lymphoma the marrow involvement tends to be much less.

The anti-B antibodies in a patient with blood group A belong to the IgM class of immunoglobulins.Note:IgM is the largest antibody formed of 5 antibodies attached together. This functions to agglutinate or clump antigens. The associated anti-A and anti-B antibodies are usually IgM produced in the first years of life by sensitisation to environmental substances such as food, bacteria, and viruses.Other options:- IgG is the most common antibody. It is a single antibody complex.- IgD is found on the surface of B-lymphocytes.- IgE is bound to tissue cells, especially mast cells and eosinophils.

Hematopoietic stem cells (HSCs) are a rare population of cells residing in the bone marrow (BM) and continuously replenish all mature blood cells throughout their life span.

Carbon monoxide is a colourless gas, which is toxic to animals. It has a high affinity for haemoglobin (around 250 times greater than oxygen). It combines with haemoglobin forming carboxyhaemoglobin, which decreases the oxygen-carrying capacity of the blood, leading to a left-shift in the oxygen-dissociation curve. CO is produced endogenously in limited amounts (0.4ml per hour), but the toxic levels are higher.