A 85 year old female was presented with worsening lower back pain following a fall two weeks prior to admission. Past medical history included hypertension, diastolic heart failure, obesity and anemia. Physical exam was unremarkable except for lumbar L1-L3 bony tenderness but no neurological deficit.
Pertinent laboratory findings were: corrected calcium of 14 mg/dL, phosphorus of 3.1 mg/dL and creatinine of 1.1 mg/dL. A Computed Tomography of the lumbar spine revealed an acute comminuted L1 vertebral body fracture and a suspicious lytic lesion in the vertebral body of L3.
Hypercalcemia was medically managed with aggressive hydration, forced diuresis and bisphosphonates. She underwent a kyphoplasty with vertebral biopsy of L1. Workup revealed vitamin D deficiency and normal parathormone (PTH) and parathormone-related peptide (PTH-rp) level and no monoclonal paraprotein on serum or urine protein electrophoresis (SPEP/ UPEP); serum free light chain (FLC) ratio was normal as well.
A skeletal bone survey showed extensive punched out lytic bone lesions on femur and humerus. Pathological findings of vertebral biopsy as well as iliac crest bone marrow biopsy revealed a plasma cell infiltration of nodular distribution, occupying 60 percent of marrow cellularity. All these findings were consistent with the diagnosis of a non-secretory myeloma. Patient was initially started on dexamethasone with plan to start chemotherapy as outpatient later though she decided against further treatment.
Discussion:
Only about 3 percent of the patients with MM have normal SPEP/ UPEP and normal FLC ratio pathognomic for true non-secretory multiple myeloma.If a hypercalcemic patient has normal phosphorus, vitamin D, PTH, PTH-rp, SPEP/ UPEP and FLC assay; a true non-secretory multiple myeloma should be suspected.
Biopsy of bone lesions or bone marrow is now routinely recommended in all patients who are suspected to have MM to avoid delay in diagnosis and rule out the non-secretory cases.
Conclusions:
Non-secretory multiple myeloma (MM) is a rare hematologic malignancy. It often poses a diagnostic dilemma and could be misdiagnosed as secondary malignancies, osteoporosis or secondary hyperparathyroidism