WBC Disorders - Dyscrasias, Langerhans Cell Histiocytosis

Question 1

Multiple Myeloma

Answer 1

Malignant proliferation of plasma cells in bone marrow.
Most common primary malignancy of bone (mets overall).
^ IL-6 –> plasma cell growth and immunoglobulin production.

Bone pain w hypercalcemia - activate RANK receptor in osteoclasts –> lytic punched out lesions esp in vertebrae and skull –> ^ fracture risk.
^ serum protein - immunoglobulin; M spike on SPEP due to monoclonal IgG or IgA.
^ risk of infection - monoclonal ab lack genetic diversity - most common cause of death.
Rouleaux formation of RBCs - ^serum protein–> v RBC charge –> clumps of RBCs.
Primary AL amyloidosis - free light chains circulate and deposit in tissues.
Proteinuria - free light chain excreted as Bence Jones protein - ^ risk renal failure (myeloma kidney).

Question 2

Monoclonal Gammopathy of Undetermined Significance (MGUS)

Answer 2

^ serum protein w M spike on SPEP.
Other multiple myeloma features absent.
Elderly.
1% develop multiple myeloma.

Question 3

Waldenstrom Macroglobulinemia

Answer 3

B-cell lymphoma w monoclonal IgM production.
Generalized LAD,
^ serum protein w M spike (of IgM).
Visual and neuro deficits - IgM (large pentamer) –> serum hyperviscosity.
Bleeding - viscous serum –> defective platelet aggregation.
Tx w plasmapheresis to remove IgM.

Question 4

Langerhans Cell Histiocytosis

Answer 4

Langerhans cells = specialized dendritic cells in skin.
From bone marrow monocytes.
Present antigen to naive T cells.

Langerhans cell histiocytosis = neoplastic proliferation or Langerhans cells.
Birbeck granules (tennis racket).
CD1a+, S100+

Memory:
people’s names - malignant, involves skin
2 names - kids <2
3 names - kids >3

Question 5

Letterer-Siwe Disease

Answer 5

Malignant proliferation of Langerhans cells.
Skin rash and cystic skeletal defects in infants (<2).
Multiple organs.
Rapidly fatal.

Question 6

Eosinophilic Granuloma

Answer 6

Benign proliferation of Langerhans cells.
Bone (differential w osteosarcoma).
Pathologic fracture in adolescent.
No skin involvement.
Langerhans cells w mixed inflammatory cells.
Numerous eosinophils.

Question 7

Hand-Schuller-Christian Disease

Answer 7

Malignant proliferation of Langerhans cells.

Scalp rash, lytic skull defects, diabetes insipidus, exophthalmos in child (>3).