PATH - Myelomas

Question 1

Multiple myeloma

Answer 1

Monoclonal *plasma cell (“fried egg” appearance) cancer that arises in the *marrow and produces large amounts of *IgG (55%) or
*IgA (25%)

Numerous plasma cells with “clock-face” chromatin and intracytoplasmic inclusions
containing immunoglobulin.

Associated with:
ƒ-INC susceptibility to infection
-Primary amyloidosis (AL)
ƒ-Punched-out lytic bone lesions on x-ray
ƒ-M spikes on serum protein electrophoresis
ƒ-Ig light chains in urine (Bence Jones protein)
ƒ-Rouleaux formation (RBCs stacked like poker chips in blood smear)

Think CRAB:
HyperCalcemia
Renal involvement
Anemia
Bone lytic lesions/Back pain

Most common 1° tumor arising within bone in people > 40–50 years old.

Question 2

Monoclonal gammopathy of undetermined significance (MGUS)

Answer 2

monoclonal expansion
of *plasma cells

*NO “CRAB” findings

asymptomatic, may lead to
multiple myeloma.

Patients with MGUS develop multiple myeloma at a rate of 1–2% per year.

Question 3

Waldenström

macroglobulinemia

Answer 3

• M spike = IgM hyperviscosity syndrome (eg, blurred vision, Raynaud phenomenon)
• NO “CRAB” findings.

Question 4

Myelodysplastic syndromes

Answer 4

Stem-cell disorders involving ineffective hematopoiesis–>defects in cell maturation of
all nonlymphoid lineages.

Caused by de novo mutations or environmental exposure (radiation, benzene, chemotherapy).

Risk of transformation to AML

*Pseudo–Pelger-Huet anomaly—neutrophils
with bilobed nuclei.
-Typically seen after chemotherapy.