Heme-Pathology (2) Flashcards
What is the first step in heme synthesis?
glycine + succinyl CoA are combined using vitB6 to form delta-aminolevulinic acid
Enzyme: d-aminolevulinic acid synthase (defect= sideroblastic anemia)
in the mitochondria
What is the second step in heme synthesis?
delta-ALA to porphobilinogen using delta-ALA dehydratase (lead poisoning)
in the cytoplasm
What is the third step in heme synthesis?
porphobilinogen to hydroxymethlbilane using porphobilinogen deaminase (acute intermittent porphryia)
in the cytoplasm
What are the 4th and 5th steps in heme synthesis?
4th: hydroxymethlbilane to uroporpyrinogen III
5th: uroporpyrinogen III to coprophyrinogen III using uroporphyrinogen decarboxylase (porphyria curanea tarda)
both in the cytoplasm
What is the 6th step in heme synthesis?
coprophyrinogen III to protoporphyrin and then to heme using Fe2+ and ferrochelatase (lead poisoning)
in the mitochondria
How does iron poisoning cause death?
cell death occurs due to peroxidation of membrane lipids resulting in symptoms such as:
N/V, gastric bleeding and scarring
How is iron poisoning tx?
IV deferoxamine, oral deferasirox for chelation
dialysis
What is a prothombin test used for?
tests function of common and extrinsic pathway factors I II, V, VII, and X
What is a PTT used for?
common and instrinic factor tests: all factors except VII, and XIII
How do Hemophilia A,B, or C react to a PT or PTT?
increased PTT only
MOI of Hemophilia A? B? C?
A and B: X-linked recessive
C: AR
How does hemophilia present?
macrohemorrhage- bleeding into joints, easy bruising
How does Vit K deficiency react to a PT or PTT?
both increased but bleeding time normal
What things increase bleeding time?
defects in platelet plug formation
What is immune thrombocytopenia?
the presence of Anti-GpIIB/IIIa Abs that bind platelets and result in splenic macrophage of the complex, commonly following viral illness
Describe TTP
Inhibition of deficiency of ADAMTS13 cleavage protein causes larger than usual vMF multimers that increase platelet adhesion and cause thrombosis
How does TTP present?
pentad of:
neurological and renal symptoms
fever
thrombocytopenia
and microangiopathic hemolytic anemia
What is the tx of TTP?
plasmapheresis and steroids
Which is elevated in von Willebran disease, PT or PTT? Why?
Intrinsic pthway coag defect, so PTT (vmF acts as a carrier of factor VIII)
Describe von Willebrand disease
AD disorder caused by a lack of circulating vMF leading to a mild bleeding disease and tx with desmopressin
What is DIC?
Widespread activation of clotting leading to a deficiency in clotting factors and eventually a leading state where both PT and PTT are elevated
What are some causes of DIC?
STOP Making New Thrombi
Sepsis (gram neg)
Trauma
Obstetric Complications
acute Pancreatitis
Malignancy
Nephrotic Syndrome
Transfusion
How does DIC present in labs?
increased PT AND PTT
schistocytes
increased fibrin split products (d-dimers)
decreased fibrinogen, factors V and VIII
Describe antithrombin deficiency
this is an inherited deficiency (can also be acquired) that has no direct effect on PT, PTT, or thrombin time but diminishes the increase in PTT following heparin administration
How can antithrombin deficiency be acquired?
renal failure/nephrotic syndrome with loss in urine leading to increased activity of factors IIa and Xa and hypercoagulopathy
What is Factor V Leiden?
production of mutant Factor V that is resistant to degradation by activated protein C (most common caused of inherited hypercoaguloability in whites)
What does a Protein C/S deficiency cause?
a decreased ability to inactivate factors Va and VIIIa increasing the risk of thrombotic skin necrosis with hemorrhage following administration of warfarin
What are the options in blood transfusion therapy?
- packed RBCs
- platelets
- fresh frozen plasma
- cyroprecipitate
What are the effects of giving packed RBCs?
increased Hb and O2 carrying capacity for acute blood loss or anemia
What are the effects of giving platelets?
What are the effects of giving FFP?
increased coag factors for tx od DIC, cirrhosis, or immediate warfarin reversal
What are the effects of giving cryoprecipitate?
contains fibrinogen, factor VIII, XIII, vFM, and fibronectin
What are the main risks of bloof infusion?
- iron overload
- hypocalcemia (citrate is a Ca2+ chelater)
- hyperkalemia (RBCs may lyse)
What is leukemia?
lymphoid or myeloid neoplasm with widespread involvement of bone marrow with tumor cells found in peripheral blood
What is lymphoma?
disrete tumor mass arising from lymph nodes
What is a leukemoid rxn?
an acute inflammatory response to infection, resulting in increased WBC count with increased neutrophils, a left shift, and increased leukocyte alkaline phosphatase (LAP)
NOTE: CML also increases WBC with left shift but does NOT elevate LAP
Describe Hodgkin lymphoma
a localized, single group of nodes involved with extranodal invovlement rare and only continguous spread (i.e. much better prognosis than non-Hodgkin lymphoma)
What is the strongest predictor of Hodgkin lymphoma prognosis?
stage
what is the classic cell seen in Hodgkin lymphoma?
CD15+ and CD30+ Reed-Sternberg cell
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Who gets Hodgkin lymphoma?
bimodal with young adulthood and 55+ common; more common in men exept the nodular sclerosing type
HL has a strong association with _____
EBV
Describe Non-Hodgkin lymphoma (NHL)?
multiple, peripheral node involvement, with extranodal involvement common and noncontiguous spread
Who gets Non-Hodgkin lymphoma (NHL)?
20-40 yo mostly
Which forms of Hodgkin lymphoma have the a) best and b) worst prognosis?
a) lymphocyte-rich
b) lymphocyte-mixed or depleted
What are some non-Hodgkin neoplasms of mature B cells?
- Burkitt lymphoma
- Diffuse large B-cell lymphoma
- Follicular lymphoma
- Mantle cell lymphoma
Who gets Burkitt lymphoma?
adolescents
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What mutations are common in Burkitt lymphoma?
t(8:14) translocation of c-myc (8) and heavy chain Ig (14)
What is this?
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Starry-sky appearnace (sheets of lymphocytes with interspered macrophages) in Burkitt lymphoma
Burkitt lymphoma has a strong association with _____
EBV
Who gets diffuse large-B cell lymphoma?
usually older adults, but 20% in children (most common type of non-Hodgkin lymphoma in adults)
Who gets follicular lymphoma?
adults
What mutation is present in follicular lymphoma?
t(14:18) of heavy chain Ig (14) and BCL-2 (18)
Describe follicular lymphoma
indolent course with BCl-2 inhibiting cellular apoptosis and presenting with painless waxing and waning LAD
Mantle cell lymphoma also occurs in older males. What mutation is present?
t(11:14) of cyclin D1 (11) and heavy-chain Ig (14)
Mantle cell lymphoma is __+
CD5
What causes adult T-cell lymphoma?
HTLV (associated with IVDU)
What is this?
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Mycosis fungoides/Sezary syndrome
What is Multiple Myeloma?
a neoplasm arising from a monoclonal plasma cell (fried egg apearance) that arises in marrow and produces large amounts of IgG (55%) or IgA (25%)
What are the symptoms of MM?
CRAB
hyperCalcemia
Renal Involvement
Anemia
Bone lyitc lesions/Back pain
What are some associations of MM?
- infection susceptibility
- primary amyloidosis (AL)
How does MM appearance on x-ray?
punched-out lytic bone lesions
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How does MM appear on serum protein electrophoresis?
M spike
What are two unique findings with MM?
- Ig light chains in urine (Bence Jones protein)
- Rouleaux formation, stacked RBCs (below)
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How is MM distinguished from Waldenstrom macroglobulinemia?
WM is associated with an M spike that is IgM and is a hypervisocity syndrome (e.g. blurred vision, Raynaud phenomenon); no CRAB
Describe Monoclonal gammopathy of undeterined significance (MGUS)
this is a monoclonal expansion of plasma cells, asymptomatic, that may lead to MM (1-2%/yr); no CRAB
What are myelodysplastic syndromes?
stem-cell disorders involving ineffective hematopoiesis causing defects in cell maturation of all non-lymphoid linages caused by de novo mutations or environmental exposure (e.g. radiation, benzene, chemo)
myelodysplastic syndromes have a significant risk of transformaiton to _____
AML
What is Pseudo-Pelger-Huet anomaly?
the formation of neutrophils with bilobed nuclei seen after chemo
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Describe what happens in leukemias
unregulated growth and differentiation of WBCs in bone marrow causes bone marrow failure leading to anemia, infections, and hemorrhage
What are some lymphoid leukemias?
- acute lymphoblastic leukemia/lymphoma (ALL)
- small lymphocytic lymphoma (SLL)/chronic lymphocytic leukemia (CLL)
- Hairy cell leukemia
Who gets ALL?
15 and under yo
How can T-cell ALL present?
mediastinal mass
ALL is associated with what?
Down syndrome
What mutation has a good prognosis in ALL?
t(12:21)
Who gets CLL?
60+ yo
What is this?
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Hairy cell leukemia, a leukemia of adults
What are some myeloid leukemias?
- acute myelogenous leukemia (AML)
- Chronic myelogneous leukemia (CML)
Auer rods (below) are seen in what?
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AML
CML has what classic mutation?
Philadelphia chromosome t(9;22), BCR-ABL
CML
myeloid stem cell proliferation that may transform to AML or ALL
One tx option for CML is what?
Imatinib
What is Langerhan cell histiocytosis?
a collective group of proliferative disorders of dendritic (Langerhans) cells that presents in children as lytic bone lesions and skin rash or as recurrent otitis media with a mass involving the mastoid bone
Findings of Langerhans cell histiocytosis
- S-100 and CD1a positive
- Birbeck granules (aka ‘tennis rackets’ on EM)
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What is polycythemia vera?
disorder of increased hematocrit associated with a JAK2 mutation that may present as intense itching after a how shower due to increased basophil action
What is a classic but rare symptom of polycythemia vera?
erythromelalgia, severe, burning pain and red-blue coloration due to episodic clots in extremity vessels
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What is essential thrombocytosis?
similar to polycythemia vera, but specific for overproduction of abnormal platelets resulting in bleeding and/or thrombosis. Bone marrow contains enlarged megakaryocytes
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What is myelofibrosis?
obliteration of bone marrow due to increased fibroblast activity in response to proliferation of monoclonal cell lines resulting in characteristic ‘teardrop’ cells (below)
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What cell lines are elevated in polycythemia vera? Mutations?
RBCs, WBCs, and platelets elevated
JAK2 mutation
What cell lines are elevated in essential thrombocytotis? Mutations?
platelets; JAK2
What cell lines are changed in myelofibrosis? Mutations?
RBCs decreased, others variable; JAK2
What cell lines are changed in CML? Mutations?
RBCs- decreased
WBCs, platelets- increased
Philadelphia chromosome