Myeloma is a malignant hematologic neoplasm arising from clonal proliferation of abnormal plasma cells within the bone marrow, most commonly presenting as multiple myeloma (MM) — a disseminated form involving multiple skeletal sites simultaneously. Unlike lymphoma, which arises primarily from lymph nodes, or leukemia, which circulates predominantly in the peripheral blood, myeloma is fundamentally a bone marrow-based malignancy, though it can extend into soft tissue as extramedullary plasmacytoma (C90.20-C90.22). The pathological mechanism involves unchecked clonal expansion of plasma cells that secrete a monoclonal protein (M-protein or paraprotein), leading to bone destruction via osteoclast activation, hypercalcemia, renal impairment, anemia, and immune suppression — collectively remembered by the mnemonic CRAB (hyperCalcemia, Renal failure, Anemia, Bone lesions). The most common coding-relevant subtypes include: multiple myeloma (C90.00-C90.02), plasma cell leukemia (C90.10-C90.12), extramedullary plasmacytoma (C90.20-C90.22), and solitary plasmacytoma (C90.30-C90.32). Myeloma is commonly confused with Waldenström macroglobulinemia (C88.0), which also involves plasma cell-like cells producing IgM, but the key distinction is that Waldenström’s involves lymphoplasmacytic lymphoma and does NOT typically produce CRAB criteria bone lesions the way classic myeloma does.
Greek -μα (-ma), suffix applied to verbs to form result nouns
Noun-forming suffix — “tumor,” “mass,” “morbid growth” — used in medical Latin/Greek to denote an abnormal tissue mass
The word entered English in the 1840s as myeloma (noun), coined in New Latin from Greek μυελός (muelós, “marrow” — a word of unknown deeper origin) + -oma (tumor suffix). It was first formally used in medical literature around 1848 to describe a tumor composed of bone marrow cells. The root myelos (“marrow”) connects myeloma to the entire myelo- root family: myeloblast (myelo- + -blast → immature marrow cell), myelofibrosis (myelo- + fibrosis → scarring of bone marrow), and myelodysplasia (myelo- + dysplasia → disordered marrow development). The productive suffix -oma appears across medicine in sarcoma, lymphoma, melanoma, carcinoma, and glioma.
🔀 ALIASES / ALTERNATE TERMS
Myelomatous(adjective form — used in clinical collocations such as “myelomatous bone lesions,” “myelomatous infiltration,” “myelomatous effusion”)
Multiple Myeloma (MM)(most common lay and clinical term; used universally across hematology/oncology settings; coded as C90.00-C90.02 based on remission status)
Plasma Cell Myeloma(formal WHO classification synonym for multiple myeloma; same code family C90.0)
Kahler’s Disease(historical eponym, rarely used in modern coding; maps to C90.0x)
Myelomatosis(older clinical term for disseminated myeloma; maps to C90.00 when not in remission)
Solitary Plasmacytoma(single isolated plasma cell tumor — osseous or extramedullary; coded C90.30-C90.32; distinct from disseminated MM)
Extramedullary Plasmacytoma(plasma cell tumor arising outside the bone marrow, e.g., soft tissue, upper respiratory tract; C90.20-C90.22)
Plasma Cell Leukemia(aggressive variant where >20% of peripheral blood cells are plasma cells; C90.10-C90.12)
Smoldering Multiple Myeloma (SMM)(asymptomatic/precursor form meeting M-protein criteria without CRAB symptoms; monitor vs. treat decision; coded C90.00 when documented as myeloma)
MGUS (Monoclonal Gammopathy of Undetermined Significance)(pre-malignant precursor; NOT myeloma — coded D47.2; important not to conflate with C90.0x)
🔗 RELATED TERMS
Plasmacytoma — localized form of plasma cell neoplasm; unlike myeloma, it is confined to a single site and may be cured with radiation; subclassified as osseous (C90.30) or extramedullary (C90.20)
Plasma Cell Leukemia — shares the myelo- and plasma cell lineage; a leukemic variant of myeloma with >20% circulating plasma cells; coded C90.10-C90.12; more aggressive prognosis than classic MM
Waldenström Macroglobulinemia — closely related plasma cell neoplasm producing IgM paraprotein; arises from lymphoplasmacytic lymphoma (C88.0); distinguished from myeloma by absence of lytic bone lesions and CRAB criteria
MGUS — Monoclonal Gammopathy of Undetermined Significance; precursor/pre-malignant plasma cell proliferation without end-organ damage; coded D47.2; annual progression risk to myeloma ~1%
Hypercalcemia — cardinal CRAB feature of myeloma caused by osteoclast-mediated bone resorption; code additionally with E83.52 (Hypercalcemia) when documented
Osteolysis — mechanism of bone destruction in myeloma; myeloma cells stimulate osteoclasts via RANK-L pathway, causing punched-out lytic lesions on skeletal survey
Amyloidosis — complication of myeloma where misfolded immunoglobulin light chains deposit in tissues; systemic AL amyloidosis (E85.81) is a distinct but commonly co-occurring diagnosis
Myelofibrosis — shares the myelo- root; a distinct myeloproliferative neoplasm (D47.4) involving bone marrow fibrosis — NOT a form of myeloma, but can be confused on marrow biopsy
Myelodysplastic Syndrome (MDS) — another marrow-based malignancy; arises from myeloid rather than plasma cell lineage; D46.x; commonly confused with myeloma in documentation
Bone Marrow Biopsy — primary diagnostic procedure for confirming myeloma; required to establish clonal plasma cell percentage (≥10% confirms diagnosis); CPT 38222
Serum Protein Electrophoresis (SPEP) — key diagnostic lab identifying M-protein spike characteristic of myeloma; supports initial workup and monitoring
CODING CORNER
🏥 ICD-10-CM CODES
Multiple Myeloma (C90.0 — Remission Status Required)
Immunoelectrophoresis; serum (used to characterize M-protein type in myeloma workup)
⚠️ Coding Note: All C90.0x-C90.3x codes require a 5th-character remission status — you must specify whether the myeloma is not in remission (x0), in remission (x1), or in relapse (x2); defaulting to “NOS” maps to the x0 “not having achieved remission” code, so always query the physician if remission/relapse status is not documented. When multiple myeloma is described as metastatic to bone, do NOT add a separate bone metastasis code (C79.51) — bone involvement is inherent to myeloma and adding C79.51 is a well-known inpatient profee overcoding trap. For inpatient profee sequencing, C90.0x is typically the principal diagnosis when the admission is for treatment or management of the myeloma itself; complications like acute kidney injury or hypercalcemia may drive DRG but are generally sequenced as secondary. Watch for documentation of smoldering myeloma — if the provider documents “smoldering” but has NOT documented active CRAB criteria, query before defaulting to C90.00; some payers and guidelines treat SMM as a precursor rather than an active malignancy. For stem cell transplant admissions, ensure autologous (38241) vs. allogeneic (38240) is clearly documented, as this significantly impacts DRG assignment and reimbursement.