Explanation:

A 3 year old with a tumor of the kidney most likely has Wilms tumor. This aggressive lesion (now with a 90% survival rate thanks to modern management) is microscopically interesting because it contains embryonic glomerular and tubular structures embedded in a spindle cell stroma which may also contain smooth muscle, striated muscle bone, cartilage, fat, and fibrous tissue. On gross examination the tumor appears as a very large well demarcated mass usually occurring unilaterally but may be bilateral if familial. It is caused by a deletion of a tumor suppressor gene WT1 on chromosome 11. Wilms tumor can manifest itself through abdominal mass and hypertension, nausea hematuria and intestinal obstruction. It may also be associated with other congenital anomalies (WAGR Complex): Wilms Tumor, Aniridia genitourinary malformation and mental-motor retardation. Abundant clear cells are a feature of renal cell carcinoma. Eosinophilic cells packed with mitochondria suggest oncocytoma. Hamartomatous blood vessels suggest angiomyolipoma. Necrotic bacterial forms in macrophages suggest malakoplakia, which can cause mass lesions in the kidney without being a true tumor.

Explanation:

The only childhood malignancy listed is Wilms tumor, which commonly presents in a toddler as a large abdominal mass. Wilms tumor can also present as part of the WAGR syndrome which is characterized by aniridia, genital anomalies, and mental retardation. There is now a 90% survival rate for this tumor with combined therapy including surge, chemotherapy, and radiotherapy. Renal cell carcinoma, squamous cell carcinoma of the bladder and transitional cell carcinoma of the bladder are malignant tumors of adults. Renal hamartoma (fibroma) causes a small, gray, benign module in the renal pyramids and is usually identified only as an incidental finding at autopsy.

Explanation:

Fanconi´s anemia, an autosomal recessive disease of chromosomal instability, presents with massive skeletal malformations and hyperpigmentation of the skin. Pancyopenia and aplastic anemia are present. None of the other choices exhibit the same types of symptoms as the ones described in the question.

Explanation:

Von Willebrand´s disease is a hereditary deficiency of von Willebrand´s factor (VWF), which causes platelet dysfunction. Bleeding tendency is usually mild. Screening test show a prolonged bleeding time, normal platelet count, and, possibly, a slightly pronged PTT. Diagnosis is based on low levels of VWF antigen, and abnormal ristocetin cofactor activity. Treatment involves control of bleeding with replacement therapy cryoprecipitate or pasteurized intermediate- purity factor VIII concentrate) or desmopressin.
Hemophilia A and hemophilia B (Christmas disease) are X-linked congenital bleeding disorders affecting male infants, usually diagnosed through family history and prolonged PTT. Undiagnosed hemophilia may cause severe bleeding with circumcision. It can also result in significant ecchymosis with minimal trauma or joint and muscle bleeding, usually by the end of infancy or in early childhood. These children have a significantly prolonged PTT and normal PT. Diagnosis is made through measurement of Factor VIII activity for Hemophilia A and Factor IX activity for Hemophilia B.

Explanation:

Von Willebrand´s disease is a hereditary deficiency of von Willebrand´s factor (VWF), which causes platelet dysfunction. Bleeding tendency is usually mild. Screening tests show a prolonged bleeding time, normal platelet count, and, possibly, a slightly prolonged PTT; – Bleeding manifestations are mild to moderate and include easy bruising; bleeding from small skin cuts that may stop and start over hours; sometimes, increased menstrual bleeding; and abnormal bleeding after surgical procedures (eg, tooth extraction, tonsillectomy). Diagnosis is based on low levels of VWF antigen and abnormal ristocetin cofactor activity. Treatment involves control of bleeding with replacement therapy (cryoprecipitate or pasteurized intermediate-purity factor VIII concentrate) or desmopressin.

Explanation:

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is an X-linked enzymatic defect common in blacks that can result in hemolysis after acute illnesses or intake of oxidant drugs (including salicylates and sulfonamides). Diagnosis is based on assay for G6PD, although tests are; often falsely negative during acute hemolysis. Treatment is supportive. Hemolysis occurs commonly after fever, acute viral and bacterial infections, and diabetic acidosis. Hemolysis also occurs after exposure to drugs or to other substances that produce peroxide and cause oxidation of Hb and RBC membranes. These drugs and substances include primaquine, salicylates, sulfonamides, nitrofurans, phenacetin, naphthalene, some vitamin K derivatives, dapsone, phenazopyridine and fava beans.

Explanation:

Idiopathic throiubocytopenic purpura is a bleeding disorder caused by thrombocytopenia not associated with a systemic disease. Typically, it is chronic in adults but is usually acute and self limited in children; Spleen size is normal. Diagnosis requires that other disorders be excluded through selective tests. Treatment includes corticosteroids, splenectomy, and, for life-threatening bleeding platelet transfusions and IV immune globulin.

Explanation:

This child has evidence of mild microcytic anemia, which is most commonly caused by iron deficiency related to reduce dietary intake. Less common causes are thalassemia and lead poisoning. Hemolysis usually causes a normocytic anemia with an elevated reticulocyte anemias.

Explanation:

Thalassemias are a group of inherited microcytic, hemolytic anemias characterized by defective Hb synthesis. They are particularly common in people of Mediterranean, African, and Southeast Asian ancestry. Symptoms and signs result from anemia, hemolysis, splenomegaly, bone marrow hyperplasia, and, if there have been multiple transfusions, iron overload. Beta-thalassemia results from decreased production of beta-polypeptide chains. Alpha-thalassemia, which results from decreased production of alpha-polypeptide chains. Diagnosis is based on quantitative Hb analysis (hemoglobin electrophoresis). Treatment for severe forms may include transfusion, splenectomy, chelation, and stem cell transplantation.

Explanation:

It is important to screen for anemia during late infancy. Iron deficiency is the most common cause of anemia in this age group. There is evidence that persistent iron deficiency in childhood may have a negative impact on cognitive development.
A therapeutic trial of iron is the best approach to the treatment of iron deficiency in late infancy. If the anemia fails to respond, investigating other causes of anemia is indicated.

Explanation:

Individuals with familial polyposis have a greater risk for the development of colon cancer than do other people. The other conditions are not known to be associated with an increased incidence of colon cancer.

Explanation:

Maternal SLE does not cause hemolysis in newborns. All of the other conditions are associated with congenital hemolytic anemia.

Explanation:

Von Hippel-Lindau disease, an autosomal dominant disorder, manifests with hemangiomas within the cavernous sinus. The hemangiomas can also be located in the cerebellum, brainstem, eye, and visceral tissue, such as the pancreas and the liver.

Explanation:

The tumor is a neuroblastoma which is one of the principal forms of cancer in children. The primary differential diagnosis is Wilms tumor. Neuroblastoma typically occurs before age 5 years with many presenting before age 2. Patients typically present with palpable abdominal masses detected on physical examination, and less commonly with pain or neurologic impairment. Neuroblastoma can arise from neural crest cells throughout the body, but the adrenal medulla is the most common site. These cells populate both the medulla and the sympathetic chain, and their pluripotency results in varying degrees of differentiation of these tumors. Homer Wright pseudorosettes are circles of tumor cells with central young nerve fibers arising from the tumor cells. The oncogene associated with Neuroblastoma is N- myc. erb-B2 (choice A) is associated with breast, ovarian, and gastric carcinomas. c-myc is associated with Burkitt lymphoma. L-myc is associated with small cell carcinoma of the lung. ret is associated with multiple endocrine neoplasia, types II and III.

Explanation:

Rh incompatibility between mother and fetus is a common cause of erythroblastosis fetalis, resulting in hemolysis. Maternal vasculitis can produce some hemolysis in the mother, but does not cause erythroblastosis fetalis. Maternal anemia, exchange transfusion, and maternal diabetes do not result in this syndrome.

Explanation:

Severe beta thalassemia occurs in patients who are homozygous for mutations that lead to a decrease in beta globin synthesis. Frequent blood transfusions to correct the anemia can lead to hemochromatosis and bronze pigmentation with cardiac abnormalities. The only drug available for use in removal of iron is deferoxamine. This excess iron comes from the blood transfusions. Hydroxyurea is used for patients who have sickle cell anemia. Dimercaprol is a chelating agent for lead and mercury poisoning. Improvement in symptoms of lead poisoning occurs with treatment with N-acetyl penicillamine. Nitrite is an antidote for cyanide poisoning.

Explanation:

Since Factor VIII preparations contaminated with HIV virus were administered to hemophiliacs in the 1980s, AIDS is common in this population, and such patients can develop pneumocystis pneumonia. No reports of Factor VIII preparations contaminated with pneumocystis organisms have been reported. Neither asthma nor hypersensitivity lung disease predispose to pneumocystic infection. Water contaminated with pneumocystis organisms has not been associated with infection in the immunocompetent host.

Explanation:

Wilms tumor a neoplasm of the embryonic renal blastema, contains both a neoplastic epithelial and a stromal component. In addition to organizing as islands of stromal or epithelial cells, these cells characteristically organize into recognizable glomerular and/or tubular structures that may represent minority or sizable component of the tumor. Rhabdomyosarcoma is a malignancy of skeletal muscle origin, and the cells are recognized by their cytoplasmic content of eosinophilic muscle proteins (thin and thick filaments). Rhabdomyosarcoma has embryonal, alveolar, and pleomorphic variants, but none demonstrates a triphasic histology. Ewing sarcoma appears as a monotonous mass of primitive, small, round cells with a thin rim of clear cytoplasm. Ewing sarcoma is a tumor of bone; presentation as an abdominal mass is distinctly unusual. Hodgkin disease is a lymphoid malignancy that presents with lymphadenopathy, typically in the cervical or mediastinal nodes. The cellular component contains varying amounts of inflammatory cells and Reed-Sternberg cells. Neuroblastoma frequently presents as an abdominal mass in children; however, it does not have an epithelial component. The cell population of neuroblastoma ranges from primitive, small, blue, round cells to well differentiated neuritic cells resembling ganglion cells.

Explanation:

This is a patient is of Mediterranean descent (Italian) who has a microcytic anemia with an appropriate reticulocyte count and normal iron studies. Suspect thalassemia in a patient with a profoundly decreased MCV a major clue to the diagnosis.
Thalassemias are a heterogeneous group of inherited disorders characterized by the underproduction of either the alpha or beta chains of the hemoglobin molecule. In beta-thalassemia, a reduced production of beta chains occurs with normal amounts of alpha production. This patient most likely has beta-thalassemia major and will require lifelong transfusion therapy. Iron overload in these patients is combated with iron chelation therapy, using either Deferoxamine (now the drug of choice) or cefuroxime. Acute blood loss will not show microcytic anemia abruptly.
Anemia of chronic disease may result in a microcytic anemia; however, serum iron is low, the reticulocyte count is decreased, and these patients usually do not have such a low MCV.
G6PD (glucose-6-phosphatase) deficiency anemia is unlikely in this patient. Even though patients of Mediterranean descent are at an increased risk for the inheritance of this X-linked condition, G6PD deficiency and the other hemolytic anemias are normocytic anemias and this patient´s MCV is very low, more characteristic of a thalassemia. Iron deficiency anemia is a microcytic anemia; however, iron levels are low, reticulocyte count is low and serum ferritin is low.

Explanation:

This child is suffering from erythema infectiosum (Fifth disease), which is caused by infection with parvovirus B19. Parvovirus B19 is transmitted by the respiratory route and can affect both children and adults. In children, the illness often goes unnoticed; but when it does cause manifestations, it typically causes fever and headache followed by characteristic lacy, erythematous eruption on the bilateral cheeks. Children also typically experience symmetric arthritis or arthralgias of the large joints. Adults typically do not experience an exanthema when infected by this virus; they most commonly experience symmetric arthropathy of the small joints of the hands, wrists, ankles, and feet. The most common serious adverse effect of parvovirus B19 infection is transient aplastic crisis. The virus halts erythropoiesis in all individuals, but only patients who suffer from conditions that cause rapid erythrocyte turnover will experience symptomatic anemia. Examples of such diseases include sickle-cell anemia, hereditary spherocytosis, and autoimmune hemolytic anemia.
Henoch-Schonlein purpura (HSP) is a vasculitis that typically occurs in children or adults after an upper respiratory tract infection. Patients typically present with abdominal pain and palpable purpura on the lower extremities. The most common severe adverse effect of HSP is nephritis, which manifests with gross hematuria.
IgA deficiency is an immune deficiency characterized by complete lack of IgA. Patients are at increased risk of infections that gain access to the body through mucosal surfaces. Patients with this condition may experience anaphylaxis with transfusion of blood or blood products containing IgA.
Polycythemia vera is a neoplastic condition characterized by excessive production of erythrocytes. Patients present with splenomegaly, with aquagenic pruritus, or with an abnormally increased hematocrit on routine laboratory testing.
Porphyria cutanea tarda is a defect in porphyrin metabolism, that results from a detect in uroporphyrinogen decarboxylase. It is characterized by photosensitivity with bulla formation, scarring, alopecia, facial hypertrichosis, and dyspigmentation. Phlebotomy is one of the accepted therapies

Explanation:

Osteoid osteoma usually affects patients between the ages of 5 and 24 years. This lesion can occur in almost any bone, although it is most common in the lower extremities. Osteoid osteoma also may occur in the posterior elements of the spine. Patients usually present with fever, which is characteristically worse at night and relieved with aspirin. Since aspirin is no longer commonly used in children, the pain is now managed with naproxen or ibuprofen. The process may cause growth disturbances, such as leg length discrepancy or bowing of an extremity, or scoliosis. Radiographs usually show a sclerotic lesion and sometimes a localized lytic defect or nidus (<1 cm in diameter) within the sclerotic bone. The nidus is best demonstrated with CT. The differential diagnosis most often includes Brodie abscess or stress fracture. Histologically, the lesion consists of a nidus of immature, woven, trabecular bone and osteoblasts surrounded by dense sclerotic bone. Treatment usually involves surgical excision. Medical management with salicylates has been described and is especially useful with lesions that are difficult or unsafe to reach (e.g., a lesion at the inner aspect of the acetabulum). Newer techniques for surgical excision include percutaneous excision with CT guidance and open surgical excision with radionuclide guidance. Pain relief after surgery is usually immediate.
Brodie abscess is a chronic localized bone abscess. Subacute cases may present with lever, pain, and periosteal elevation, whereas chronic cases are often afebrile and present with long-standing dull pain. The most common site of involvement is the distal part of the tibia. The lesion is typically single and located near the metaphysic.
About 75% of patients are younger than 25. Radiographs show a radiolucent, irregularly shaped area with no adjacent osteoblastic reaction. Surgical debridement and culture- directed antibiotics are often curative.
Ewing sarcoma is a malignant tumor of bone arising in medullary tissue. It most often occurs in cylindrical bones. Prominent symptoms include pain, fever and leukocytosis. Radiographs have a typical ´onion skin appearance.”
Osteosarcoma usually presents with a painful mass.
Radiography reveals bone destruction and production, as well as periosteal elevation. Stress fractures may go undetected in standard radiographs, but a bone scan will show increased uptake.

Explanation:

The baby has wiskott-Aldrich syndrome, which is an X-linked recessive immunodeficiency disease characterized by the triad of thrombocytopenia (hemorrhage may be the presenting complaint), eczema, and recurrent infections (often respiratory). The children have defects in both T and B cell function, and are vulnerable to pyogenic bacteria, viruses, fungi, and Pneumocystis carinii. These patients have severe disease, and formerly often died by age 15. Survivors past age 10 have a 10% incidence of cancer, particularly lymphoma and acute lymphoblastic leukemia. Modern treatment consists of splenectomy, continuous antibiotic therapy, IV immunoglobulin, and bone marrow transplantation.
Congestive heart failure is not a particular problem in these children.
Crohn disease and rheumatoid arthritis are not increased in these children.
Wilms tumor usually occurs in infancy or very early childhood, and is not a specific complication of Wiskott-Aldrich syndrome.

Explanation:

This is Bruton agammaglobulinemia (X-linked agammaglobulinemia). It causes low or absent numbers of B cells, leading to a panhypogammaglobulinemia. Cellular immunity is intact the patients typically develop infections after about six months of age, when maternal antibodies have decreased to low levels. There is a life- long predisposition for recurrent pyogenic infections, particularly of the lungs, sinuses, and bones. While the condition is classically considered X-linked, this can only be proven in about 20% of cases.
These patients require life-long immunoglobulin therapy and aggressive antibiotic management when infections do develop.
Common variable immunodeficiency can have some clinical overlap with Bruton´s agammaglobulinemia, but is characterized by normal B cell levels and typically presents in the second or third decade of life.
DiGeorge syndrome typically presents with hypocalcemia in infancy.
Transient hypogammaglobulinemia of infancy has clinical overlap with Burton´s agammaglobulinemia, but can be distinguished by the presence of normal B cell numbers.
Wiskott-Aldrich syndrome is an X-linked disorder with eczema, thrombocytopenia, and recurrent infection.
Waldenström´s macroglobulinemia is associated with high globulin levels.

Explanation:

This boy most likely has acute lymphocytic leukemia (ALL). The signs and symptoms of ALL result from suppressed marrow function and invasion of organs by leukemic blasts. Anemia is present at diagnosis in most patients and causes fatigue, pallor, headache, angina, or even heart failure. Thrombocytopenia is usually present, and many patients have clinically evident bleeding at diagnosis, usually in the form of petechiae, purpura, ecchymoses, bleeding gums, epistaxis, or hemorrhage. Most patients with ALL are significantly granulocytopenic. In addition to suppressing normal narrow function, leukemic cells can infiltration normal organs.
Enlargement of lymph nodes, liver, and spleen is common at diagnosis.
Bone pain, thought to result from leukemic infiltration of the periosteum or expansion of the medullary cavity, is a common complaint ALL is the most common form of cancer and the second leading cause of death in children younger than 15 years. ALL has a maximal incidence between 2 and 10 years of age, with second, more gradual rise in frequency later in life.
Children with aplastic anemia (choice B) do not usually have bone pain, splenomegaly, and hepatomegaly.
Henoch-Schönlein purpura is a vasculitis and presents with lower extremity purpura without thrombocytopenia.
Immune thrombocytopenic purpura is a childhood disease that often follows an acute infection. It is characterized by a decrease in the circulating number of platelets (<10, 000/mm3) in the absence of toxic exposure or disease associated with low platelet count. It occurs as a secondary effect of peripheral platelet destruction as well as decreased platelet production. It usually resolves spontaneously within 2 months.
Thrombotic thrombocytopenic purpura is a systemic disorder characterized by occlusion of the microcirculation by platelet clumps.
The complete clinical pentad (present in fewer than 30% of cases) includes consumptive thrombocytopenia, microangiopathic hemolytic anemia, fever, renal dysfunction, and fluctuating neurologic deficits.

Explanation:

This patient likely has chronic granulomatous disease, a functional deficiency of neutrophils. Neutrophils are unable to generate reactive oxygen intermediates that are necessary for phagocyte-mediated killing. Patients suffer numerous infections with common pyogenic organisms. Recurrent abscesses and the presence of granulomata throughout the gastrointestinal, respiratory, or urinary tract should prompt one to think of this condition. A nitroblue tetrazolium test checks for the presence of functional catalase, which is abnormal in chronic granulomatous disease.
Complement levels are appropriate to order if one suspects a complement-mediated immune deficiency. These patients usually present with recurrent Neisseria spp. infections.
Delayed-hypersensitivity skin testing and HIV testing are appropriate in cases of suspected T-cell deficiency, which does not manifest as diffuse granulomata. Recurrent pneumonia or AIDS-defining opportunistic infections should prompt one to order an HIV test.
Quantitative immunoglobulin levels should be checked if a B- cell deficiency is suspected. B-cell disorders result in increased susceptibility to infection with extracellular pathogens, which are usually neutralized by humeral immunity. These patients are particularly at risk for pyogenic and enteric organisms and have recurrent sinopulmonary infections.

Explanation:

The constellation of lower-extremity purpura, arthritis, and abdominal pain in a young female is classic for Henoch- Schonlein syndrome, or HSP. The rash of HSP is characterized by petechiae which become purpura. Other characteristic finding of HSP includes hematuria. The rash starts out as urticarial and progresses to become petechial and purpuric. There may be a history of migratory joint pain and arthritis. Affected joints include ankles, knees, wrists, and elbows. HSP is the most common cause of non- thrombocytopenic purpura in children. A viral illness weeks before is a common antecedent to HSP. Checking the patient´s urine for hematuria is important in follow-up visits, as the patient can develop end-stage renal failure in 1% of cases. The underlying pathophysiology is related to vasculitis of small blood vessels.
Fecal leukocytosis is incorrect. The abdominal pain in this vignette is due to edema and damage to the vessels of the GI tract, and not to any infectious cause. Stool for fecal leukocytes is a useful test when a GI infection is suspected.
Thrombocytopenia is incorrect because HSP is the most common cause of non-thrombocytopenic purpura in children. In fact moderate thrombocytosis may be observed in this disorder.
White blood cell casts in urine are clusters of leukocytes in the shape of the renal tubules and are seen in pyelonephritis. Yeast in the urine is seen in patients who are on antibiotics or are immunocompromised.

Explanation:

Although the prominent clinical finding is the abdominal mass, the incidental finding of the mass by the mother, the child being asymptomatic and subtle pointers like hypertension, anemia and hematuria points towards Wilm´s tumor as the diagnosis.
Of all the tumors listed above Wilm´s tumor most frequently present as asymptomatic abdominal masses and 20-30% will have hematuria from tumor extension into renal pelvis, 25% will have hypertension from distortion of renal vasculature and anemia can be due to bleeding into tumor. The tumor crossing the midline is a subtle indicator of Wilm´s tumor but can also be seen in Neuroblastoma.
Although Neuroblastoma can present as an asymptomatic abdominal mass with hypertension, the anemia and hematuria is rare and the median age of presentation is much younger (2yrs when compared to 4yrs for Wilm´s tumor).
The presence of anemia with hypertension and hematuria is not seen in other tumors like Hepatoblastoma, Burkitt´s lymphoma or Mesoblastic Nephroma. Mesoblastic Nephroma is mostly congenital and has a much early onset of presentation.

Explanation:

This baby has a form of severe combined immunodeficiency with autosomal recessive inheritance and low antibody levels. This is most likely to be adenosine deaminase deficiency. This enzyme is a purine salvage enzyme that converts adenosine and deoxyadenosine to inosine and deoxy inosine. When the enzyme is deficient, abnormally high levels of dATP accumulate, and turn off DNA synthesis. This particularly impacts the immune system, which (for both T and B cell lines) gears up specificity by triggering massive reproduction of clones that are immunologically active against a particular antigen. Some of these children present as described; in others the immunologic defect develops more slowly and affects T cells before B cells. Bony abnormalities are common in these children. Bone marrow transplant and very recently, gene transfer, are used to treat this otherwise fatal condition.
Brutons agammaglobulinemia is characterized by pan hypogammaglobulinemia but intact T cell function.
DiGeorge syndrome is characterized by absent thymus, normal B cell function, and often hypocalcemia in infancy.
Nezelof syndrome is characterized by elevated immunoglobulins that function poorly.
X-linked severe combined immunodeficiency would not be seen in a female.

Explanation:

his table illustrates the top three most common causes of death based on age group:

Explanation:

Sickle cell anemia is chronic hemolytic anemia occurring almost exclusively in blacks, caused by homozygous inheritance of Hb S. Sickle-shaped RBCs clog capillaries, causing organ ischemia. Acute pain (crises) may develop frequently. Infection, bone marrow aplasia, or lung involvement (acute chest syndrome) can develop acutely and be fatal. Normocytic hemolytic anemia is characteristic. Diagnosis requires Hb electrophoresis and demonstration of sickling in RBCs on an unstained drop of blood. Crises are treated with analgesics and other supportive measures. Transfusions are occasionally required. Vaccines against bacterial infections, prophylactic antibiotics, and aggressive treatment of infections prolong survival. Hydroxyurea decreases the frequency of crises.

Explanation:

Causes of microcytic anemia (MCV < 80) can be remembered with the mnemonic ´TICS´, which stands for thalassemia, iron deficiency, chronic disease and sideroblastic anemia. Lead poisoning can also cause microcytic anemia. Causes of macrocytic anemia (MCV > 100) include folate and vitamin B12 deficiencies.

Explanation:

Burkitt´s lymphoma involves a translocation between c-myc on chromosome 8 and the immunoglobulin heavy chain gene on chromosome 14. The translocation results in activation of the c-myc proto-oncogene.

Explanation:

Vitamin K toxicity although uncommon, may cause vomiting and hemolysis, as well as albuminuria and hemoglobinuria. Vitamin E toxicity may cause a necrotizing enterocolitis and hepatitis in children. Vitamin D toxicity is associated with hypercalcemia, as well as constipation, and sometimes nephrocalcinosis. Pantothenic acid toxicity is associated with diarrhea. Pyridoxine toxicity, while very rare, is associated with peripheral sensory neuropathy.

Explanation:

Anti Lewis antibodies to the Lewis blood group have not been implicated in this condition. The birth of an O+ baby to an A+ mother is a compatible combination. Hepatitis A does not cause erythroblastosis fetalis. Anti-Ro antibodies are involved in SLE, but not in erythroblastosis.

Explanation:

Antibody deficient individuals will demonstrate an inability to fend off extracellular encapsulated bacteria. These persons will show a decreased level of immunoglobulin in the serum; yet owing to an intact cell mediated immune system, will be able to defend against viral infections, such as influenza virus. Growth retardation is not associated with antibody deficient disorders.

Explanation:

von Willebrand´s disease is due to a deficiency of a plasma protein that is required for the stabilization of Factor VII in the circulation and for the normal adherence of platelets to sites of vascular injury. There are different variants of von Willebrand´s disease. Type I is the most common and is associated with a prolonged bleeding time and abnormal platelet aggregation in response to ristocetin. Hemophilia B is associated with factor IX deficiency and is inherited as an X-linked disorder. Hemophilia B is associated with a normal prothrombin time and an abnormal partial prothrombin time. Bleeding is associated with stressors such as trauma or surgery. Factor VII deficiency is associated with bleeding in infancy or early childhood. It is a rare autosomal recessive defect. Afribrinogenemia is associated with a markedly prolonged bleeding time and severe hemorrhage in infancy and early childhood. Protein C deficiency is associated with an increased risk of venous thromboembolism, not bleeding.

Explanation:

This child´s blood pressure is significantly elevated for his age. The age, hypertension, and abdominal mass suggest Wilms tumor, which arises from a deletion involving chromosome 11.

Wilms tumor may occur as a part of WAGR syndrome, which consists of:

• Wilms tumor
• Aniridia
• Genitourinary abnormalities (e.g., cryptorchidism, ambiguous genitalia)
• Retardation (mental)

Fragile X syndrome is a common cause of mental retardation, but it does not explain the aniridia, the genital abnormality, and the abdominal mass.
Neuroblastoma can be differentiated from Wilms tumor by contrast-enhanced CT or ultrasonography, which distinguishes renal and nonrenal tissue (adrenal tissue), but the final diagnosis is confirmed on the basis of tissue histology by either biopsy or surgical excision.
However, although neuroblastoma can cause abdominal mass with pain and hypertension, it is not associated with WAGR syndrome.
Although renal cell carcinoma can present with similar symptoms, it is an incorrect answer because it is rare in childhood and is not associated with WAGR syndrome.
Translocation of chromosomes 9 and 22 is called the Philadelphia chromosome and causes leukemia.

Explanation:

The tumor is a neuroblastoma which is one of the principal forms of cancer in children. The primary differential diagnosis is Wilms tumor. Neuroblastoma typically occurs before age 5 years with many presenting before age 2. Patients typically present with palpable abdominal masses detected on physical examination, and less commonly with pain or neurologic impairment. Neuroblastoma can arise from neural crest cells throughout the body, but the adrenal medulla is the most common site. These cells populate both the medulla and the sympathetic chain, and their pluripotency results in varying degrees of differentiation of these tumors. Homer Wright pseudorosettes are circles of tumor cells with central young nerve fibers arising from the tumor cells. The oncogene associated with Neuroblastoma is N- myc. erb-B2 (choice A) is associated with breast, ovarian, and gastric carcinomas. c-myc is associated with Burkitt lymphoma. L-myc is associated with small cell carcinoma of the lung. ret is associated with multiple endocrine neoplasia, types II and III

Explanation:

Neuroblastoma is a childhood tumor of the sympathetic nerves that most commonly arises along the paravertebral chain or within the adrenal medulla. Children most often present with a palpable, asymptomatic abdominal mass detected on physical examination. Less commonly, they present with pain or neurologic symptoms from extension into the spinal canal. Neuroblastomas are malignancies of neuroblast (neural crest cells) which are pluripotent cells that populate the adrenal medulla and sympathetic chain and differentiate accordingly. Histopathology demonstrates small, round, blue cells of varying degrees of differentiation. Neuroblastoma has two characteristic genetic markers: a 1p deletion and an N myc translocation. N myc is an oncogene that resides on chromosome 2p and is amplified up to 300 times in neuroblastoma. Amplification of this gene is associated with a poorer prognosis. Cellular aneuploidy and hyperdiploidy reflect a better prognosis for neuroblastoma, whereas diploid and tetraploid tumors have an intermediate or poor prognosis. Tumor presentation at a younger age predicts a better outcome for neuroblastoma. Children under 1 year of age have an excellent prognosis regardless of tumor stage. Ganglion cells within the tumor are a reflection of focal differentiation of the neuroblastoma into ganglioneuroma. Better differentiated tumors have a more favorable outcome. In general, tumor stage is not very predictive of neuroblastoma survival. Nonetheless, higher grades of tumor (III and IV) extend across the vertebral midline and into distal viscera or nodes.

Explanation:

:  Sinusoidal obstruction syndrome (or veno-occlusive disease or hepatopathy) is a recognized complication of therapy with dactinomycin and cyclophosphamide.  Some rhabdomyosarcoma treatments have been associated with rates of sinusoidal obstruction syndrome of 4-5%.  In addition to elevated bilirubin, weight gain/ascites, hepatomegaly or RUQ pain, sinusoidal obstruction syndrome shows reversal of portal venous flow on Doppler study of the liver.  The correct answer is C.  This question is linked to content outline knowledge bit H.8.g.