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Myeloma


KEY FACTS

Terminology

  • Clonal B-lymphocyte neoplasm of terminally differentiated plasma cells

    • Solitary = plasmacytoma

      • –

        Brain/CNS is extramedullary plasmacytoma

    • Multifocal = multiple myeloma (MM)

Imaging

  • Intracranial MM rare (1% of MM)

  • Can occur as solitary (primary) plasmacytoma or manifestation of systemic MM (secondary)

    • Secondary

      • –

        Extension from osteolytic skull lesion > hematogenous spread

    • Primary CNS myeloma rare

      • –

        Extraaxial dural-based nonosseous lesions

      • –

        CNS “myelomatosis” involving leptomeninges &/or cranial nerves

      • –

        Parenchymal masses (discrete nodules)

  • Best overall imaging tool: Radiography (skeletal survey)

    • Detects 80% of sites in 90% of patients

    • Up to 20% of radiographs and MR may be “normal”

  • CNS disease

    • Bone CT for calvaria, skull base

    • MR ± T1 C+ FS for nonosseous intracranial lesions

Top Differential Diagnoses

  • Surgical defect

  • Lytic metastasis

  • Hemangioma

  • Hyperparathyroidism

Clinical Issues

  • Peak onset = 65-70 years

    • 1st primary bone malignancy in 4th-8th decades

    • Most common symptom: Bone pain (68%)

  • Prognosis

    • 70% of plasmacytomas progress to MM

Sagittal graphic depicts the multiple “punched-out” lesions
of multiple myeloma in the calvaria.

Lateral digital radiograph in a patient with multiple myeloma shows the classic salt and pepper appearance of the skull caused by innumerable “punched-out” lesions
.

Axial NECT in a 50-year-old man with altered mental status, “possible TIA,” shows no abnormalities.

Axial bone CT with bone algorithm reconstruction in the same patient shows innumerable well-defined lytic lesions
in the calvaria. Further evaluation disclosed metastatic multiple myeloma.

TERMINOLOGY

Abbreviations

  • Solitary = plasmacytoma (PC)

    • Solitary plasmacytoma of bone

    • Extramedullary plasmacytoma (includes brain/CNS)

  • Multifocal = multiple myeloma (MM)

Definitions

  • Clonal B-lymphocyte neoplasm of terminally differentiated plasma cells

IMAGING

General Features

  • Best diagnostic clue

    • Osteolytic skull lesion

  • Location

    • Intracranial MM rare (1% 0f MM)

      • –

        Can occur as solitary (primary) plasmacytoma or manifestation of systemic MM (secondary)

        • □

          In Waldenström macroglobulinemia (a.k.a. Bing-Neel syndrome)

        • □

          Often widely disseminated at time of diagnosis

      • –

        Secondary (extension from osseous lesions in calvaria, skull base, nose/paranasal sinuses > hematogenous spread) most common

      • –

        Primary CNS myeloma rare

        • □

          Extraaxial dural-based nonosseous lesions

        • □

          CNS “myelomatosis” involving leptomeninges &/or cranial nerves

        • □

          Parenchymal masses (discrete nodules)

  • Morphology

    • Focal, round or oval lesion(s)

Radiographic Findings

  • Radiography

    • “Punched-out” lytic lesion(s) (90%)

    • Osteopenia/osteoporosis (10%)

    • Rarely sclerotic, except following therapy

CT Findings

  • NECT

    • “Punched-out” lytic lesion(s)

    • Meningeal myelomatosis: Marked hyperdensity

  • CECT

    • MM renal failure (RF) after contrast (0.6-1.25%)

      • –

        0.15% in general population

      • –

        Thus, not 100% risk-free but may be performed if necessary and patient well hydrated

    • Meningeal myelomatosis: Uniform enhancement

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