L10 - When haemopoiesis goes wrong

Question 1

What are myeloproliferative neoplasms (MPN)?

Answer 1

A group of diseases of the bone marrow causing excess production of certain cells

Question 2

What are the four major MPN’s and what cell(s) is in excess in each of them? ALL are caused by mutations causing problems in the bone marrow

Answer 2

Polycythaemia vera (excess erythrocytes caused by a problem in the bone marrow)

Essential thrombocythaemia
(overproduction of megakaryocytes leading to excess platelets)

Primary myelofibrosis (Replacement of haemopoietic tissue with increased amounts of connective tissue - this eventually leads to a REDUCTION in all cells, a pancytopenia - cause of massive splenomegaly and sometimes hepatomegaly

Chronic myeloid leukemia (CML) - excess granulocytes

Question 3

what cancer patients with myeloproliferative neoplasm (new, abnormal growth) at risk of their diseases becoming?

Answer 3

leukemia (blood cancer, normally occurs in bone marrow)

Question 4

Other than polycythaemia vera why else would we see a raised erythrocyte count?

Answer 4

Organ hypoxia -> compensatory mechanism e.g. chronic lung disase or training at altitude/certain carcinomas that produce ectopic EPO e.g. phaeochromocytoma/

Question 5

Name some things you would have to first discount before suspecting essential thrombocythaemia

Answer 5

Infection/inflammation/tissue injury/haemorrhage/cancer

• all would lead to increase in number of platelets

NOTE - needs to be persistent to not transient

Question 6

How does chronic myeloid leukemia come about?

Answer 6

BCR-ABL fusion gene inhibits apoptosis and stimulates proliferation of myeloid cells which lead to the accumulation of granulocytes

Question 7

how could acquired thrombocytopenia come about?

Answer 7

Common - a decrease in platelet production - e.g. aplastic anaemia, leukemia, b12 folate deficiency/an increased consumption of platelets due to DIC or MASSIVE haemorrhage (using them all up) or an increased destruction of platelets - autoimmune disease/hypersplenism and thus increased splenic pooling

Question 8

what are the clinical signs of acquired thrombocytopenia?

Answer 8

Bleeding gums/nosebleeds/heavy or longer menstrual periods/petechiae (purple dots which are bruises) under the skin/severe bleeding after trauma/intracranial haemorrhage

Question 9

Common features of myeloproliferative neoplasms include thrombotic abnormalities/abnormalities associated with whatever cell is affected/marrow fibrosis and hepato or splenomegaly. Why do we see hepato/splenomegaly?

Answer 9

Because of the problems in the bone marrow haemopoiesis occurs at secondary sites

Question 10

What would the treatment regime be for polycythaemia vera?

Answer 10

venesection and aspirin

Question 11

Give some symptoms of polycythaemia vera

Answer 11

arterial and venous thrombosis/splenomegaly/pruritis/gout

Question 12

describe some classical features of myeloproliferative neoplasms

Answer 12

marrow fibrosis/thrombosis/extramedullary haemopoiesis resulting in splenomegaly and hepatomegaly/potential to transform to acute leukemia

Question 13

Aplastic anaemia would be a presenting pancytopenia with a hypocellular bone marrow, no abnormal infiltrate and no increase in fibrosis.

Answer 13

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