Mastocytosis

Question 1

A mitogen that plays a big role in mast cell growth and migration

Answer 1

SCF

Question 2

Neoplasms of mast cells usually present as…

Answer 2

benign cutaneous lesions in kids (the most common is “urticaria pigmentosa”, aka itchy pigmented skin lesions).

Question 3

When they OCCASIONALLY spread beyond skin…

Answer 3

they release lots of histamine and other mediators, causing systemic symptoms (flushing, abdominal pain, tachycardia, hypotension) that can can really confuse the clinician.

Question 4

most common site of systemic involvement

Answer 4

bone marrow

but can also involve other organs…i.e. spleen, liver, lymph nodes

Question 5

Important diagnostic indicator

Answer 5

serum tryptase level

Question 6

Fusion protein and tyrosine kinase involved…

Answer 6

FIP1L1-PDGFRB (4 partners identified)

Some respond to imatinib!!

Question 7

Morphology (bone marrow)

Answer 7

Bland looking cells, round/spindle shaped

Question 8

Percent associated w second hematologic malignancy

Answer 8

30%

Question 9

Genetics

Answer 9

Either cKIT mutants OR PDGFRA activation (FIP1) translocation

Question 10

Clinical Presentation

Answer 10

Variable and Confusing

Question 11

Morphology (General)

Answer 11

Aggregates of bland looking cells
round/sphericle shaped
sometimes w/ eosinophilia

Question 12

Immunophenotype

Answer 12

Tryptase
CD117 (cKIT)
CD25 usually positive

Question 13

Prognosis

Answer 13

Highly variable

depends on complex subclassification scheme

Question 14

Aggregates of mast cells can be subtle an bland looking, so…

Answer 14

Immunostains are key!

Question 15

cKIR

Answer 15

SCF receptor!

CD117