Review: MDS

Question 1

What is Myelodysplastic Syndromes (MDS)?

Answer 1

Defective maturation of myeloid progenitors causing ineffective hematopoiesis => cytopenias and high risk of AML transformation

Question 2

MDS or MPS: which is more severe?

Answer 2

Myelodysplastic syndrome

Question 3

What are the names of MDS?

Answer 3

RA (refractory anemia)
RARS, 
RAEB, 
RAEB-t, 
CMML, 
MDS (NOS)

Question 4

Do Myelodysplastic Syndromes lead to cytopenias or -cytosis?

Answer 4

Cytopenias (decrease in counts)

Question 5

MDS can be primary (idiopathy) or secondary (due to genotoxic drug or radiation therapy). However, both are characterized by…

Answer 5

Peripheral cytopenias

Question 6

To qualify as MDS, bone marrow must have

Answer 6

< 20% myeoblasts; more is AML

Question 7

Primary MDS is most commonly seen in whom and presents how when symptomatic?

Answer 7

• Older adults (mean age = 70)

- Presents w/ weakness (anemia), infections (neutropenia), and hemorrhages (thrombocytopenia)

Question 8

Which gene/chromosome is one of the most common forms of aneuploidy in a wide range of myelodysplastic tumors?

Answer 8

• MYC on Chr 8

Question 9

In myelodysplastic syndromes what is the common morphological findings within the erythroid lineages?

Answer 9

• Ring sideroblasts = erythroblasts w/ iron-laden mitochondria visible
• Megaloblasts = resembling that seen in B12/folate deficiency
• Nuclear budding abnormalities, misshapen, often polypoid, outlines

Question 10

Which special form of neutrophils is commonly observed with myelodysplastic syndromes?

Answer 10

Neutrophils with decreased numbers of secondary granules, toxic granulations or Dohle bodies

Pseudo-Pelger-Huet cells = neutrophils w/ only 2 nuclear lobes

Question 11

Which type of MDS has the highest frequency and most rapid transformation to AML + the WORST prognosis with a median survival of only 4-8 months?

Answer 11

t-MDS = due to previous genotoxic drug or radiation therapy

Question 12

What is Histiocytosis?

Answer 12

Rare disorder caused by proliferation of MO (histiocytes) and DC Type

Question 13

What is Langerhans cell histiocytosis (LCH)?

Answer 13

Spectrum of neoplastic disorders due to proliferation of Langerhan cells (a type of immature DC

Question 14

Are Langerhan cells mature and capable of being APC?

Answer 14

Functionally immature and do NOT effectively (+) primary T-cells via APC.

Question 15

Markers for LCH

Answer 15

o 1. S100 (mesodermal origin)
o 2. CD1a
o 3. CD207
o 4. HLA-DR

Question 16

What mutation is seen in LCH?

Answer 16

BRAF activating point mutation: Valine-to-glutamate substitution at residue 600 (same as Hairy cell Leukemia)

Question 17

How does LCH often present?

Answer 17

Presents in child as lytic bone lesion and skin rash or recurrent otitis media with a mass involving the mastoid bone.

Question 18

What do you see on histology in Langerhan Cells?

Answer 18

Birbeck granules in cytoplasm = “Tennis-racket like” cytoplasmic inclusions in Langerhan cells (seen on electron microscopy