Plasma Cell Dyscrasias

Normal plasma cell function

B‑cells that differentiate into plasma cells whose primary job is antibody secretion.

Definition of plasma cell dyscrasia

Clonal plasma cell expansion causing excess monoclonal immunoglobulin(inc in antibodies) and potential end‑organ damage.

Continuum of plasma cell disorders

Monoclonal Gammopathy of Undertmined Significance (MGUS) → Multiple Myeloma → Plasma Cell Leukemia (increasing plasma cells and protein burden).

Diagnostic test to quantify plasma cells

Bone marrow biopsy and aspirate.

Diagnostic tests to quantify monoclonal protein

SPEP, immunofixation, quantitative immunoglobulins, serum free light chains.

Clue suggesting plasma cell disorder on CMP

High total protein with normal/low albumin (albumin should dominate total protein).

Polyclonal vs monoclonal immunoglobulin pattern

Polyclonal = broad gamma region= normal

Monoclonal is very narrow(all the same protein so they all blot in same spot)

SPEP monoclonal gammopathy pattern

Single sharp gamma‑region spike representing identical immunoglobulins.

Purpose of immunofixation/Immunoelectrophoresis

Confirms clonality and identifies heavy chain (IgG/IgA/IgM) and light chain (kappa/lambda).

Serum free light chain abnormality in myeloma

Markedly elevated kappa or lambda with abnormal ratio (>1.65 or <0.26).

Bone involvement in myeloma

Lytic lesions due to increased osteoclast activation (skull, spine, ribs, pelvis, long bones).

Kidney involvement in myeloma

Cast nephropathy (“myeloma kidney”), immunoglobulin deposition, plasma cell infiltration.

Peripheral smear finding in myeloma

Rouleaux formation due to increased serum proteins.

Electrolyte abnormality in myeloma

Hypercalcemia from increased osteoclast activation (“stones, bones, groans, moans”)=kidney stones, increased bone resorption, constipation, psych issues

Anemia type in myeloma

Normocytic, normochromic anemia due to marrow infiltration.

Treatment approach for plasma cell dyscrasias

Depends on disease severity: observation → oral chemo → intensive IV chemo.

Waldenstrom’s macroglobulinemia definition

IgM‑producing plasma cell dyscrasia(IgM excess) along the same continuum as myeloma.

Why IgM causes hyperviscosity

IgM is a large pentamer that increases serum viscosity and impairs microvascular flow in really high volumes

Symptoms of hyperviscosity syndrome

Headache, vision changes, dizziness, tinnitus, ataxia — medical emergency. (similar concept to leukostasis)

Emergent treatment for hyperviscosity

Plasmapheresis (not chemotherapy).

SPEP pattern in infection

Broad gamma region increase from polyclonal immunoglobulin response.

SPEP pattern in hypogammaglobulinemia

Low/flat gamma region (e.g., CLL).

SPEP pattern in multiple myeloma(monoclonal gammopathy)

Sharp monoclonal spike in gamma region (M‑spike).

CRAB mnemonic in Plasma Cell Dyscrasias

HyperCalcemia, Renal dysfunction, Anemia, Bone lesions.

SPEP Peaks and their indications

1: Albumin peak

2: Alpha-1 peak= alpha antitrypsin

3: Alpha-2 peak: Haptoglobin

4: Beta peak: Transferrin and some immunoglobulins

5: Gamma peak: most immunoglobulins