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Path - Tumour Markers in Nodes, Spleen, Thymus + BM (i) (Myeloproliferativ…
Path - Tumour Markers in Nodes, Spleen, Thymus + BM (i)
thymus
arises from endoderm of 3rd + 4th bronchial pouch
descends: migrates from neck to ant mediastinum
T cells differentiate here - mature due to thymic hormones
shrinks/involutes after birth - almost completely atrophied as an adult
central role in cell-mediated immunity
reasons for it bring enlarged
MG
may trigger/maintain the production of anti-ACh R Igs
80% of time
thymic hyperplasia in 80% of cases (autoimmune thymitis)
thymectomy = curative Tx
neoplasms
thymomas
thymic epithelial neoplasm
15% of thyroid neoplasm cases
some benign, some malignant
can be assymtomatic unless v big
mass can be up to 10-12 cm
compresses structures in ant mediastinum (e.g. heart, bronchus)
30% associated with MG (also RA + Sjogren's)
grade to predict prognosis
lymphomas
mostly T cell, but can be B cell
germ cell tumours
arise from stem cells (more plausible) or germ cells get lodged during migration
carcinoid tumours
Myeloproliferative cell neoplasms/disorders (MCN/MCD)
clonal neoplastic prolif of stem cells (common origin)
affects all cell lines of BM
variable presentation + prognosis
Dx
clinical exam
FBC
BM trephine + aspirate
molecular tests
JAK2 mutation
janus kinase 2 (type of tyrosine kinase)
mutation: increased sensitivity to intercellular signalling
Bcr-Abl gene arrangement
pathogenesis
activating mutation in tyrosine kinase gene
classified based on cell line maximally involved (i.e. proliferating the most)
CML
leukocytosis
most common
WBCs max involved
do LAP (leukocyte alkaline phosphatase)
differentiates CML from other causes of leukocytosis
Myelofibrosis
60% due to JAK2 mutation
Polycythaemia rubra vera
90% due to JAK2 mutation
RBCs max involved
Essential thrombocythaemia / thrombocytosis
60% due to JAK2 mutation
platelets max involved
count = 1 million
frequently evolve from 1 type into another
more than 1 cell type can be involved
due to abnormal clone with increases sensitivity to GFs
excess of 1 cell type can decreased levels of other cell lines
increased no. of NON-FUNCTIONAL cells
e.g. even though you have leukocytosis you'll get more infections as they are not protective
polycythaemia: bleeding (no chance to make platelets), thrombosis (increased MCV), hyperviscosity syndrome (increased cells relative to fluid, leads to splenic infarcts)
splenomegaly
compensatory (only minor)
still destroys more cells than it makes
makes RBCs, WBC, megarkaryocytes
patient usually 50+ y/o
hyperuricaemia
increased uric acid (cell breakdown)
gout
! can transform into acute leukaemia