What is causing this man's persistent low back pain?

A 75-year-old man presented to the clinic complaining of moderate-to-severe pain in the mid to lower back for the past week. He said the pain started 2 months ago and was mild until the past week, when it progressed from 2 or 3 on a 0-to-10 pain intensity rating scale to the current rating of 8. He had been prescribed acetaminophen with codeine for a previous knee surgery, and took some of the leftover pills but with minimal pain relief. He tried some folk remedies and local heat without improvement of his symptoms.

The patient denied a history of trauma or injury to the back. His symptoms were exacerbated at night while resting and when turning in bed. He denied weakness, numbness of the lower extremities, and gait disturbance. He said he had had pain in the distal interphalangeal joints of both hands and bilateral knee pain for 5 years. For the past month he also had noted fatigue. He reported occasional breast tenderness and hot flushes for the past 2 years since starting drug therapy for prostate cancer.

The patient's past medical history included prostate cancer with a Gleason score of 3+3 (primary plus secondary grades). This patient's total Gleason score was 6. He was treated with brachytherapy 2 years ago and receives a monthly injection of hormonal therapy (leuprolide) and takes 50 mg of bicalutamide daily. He also has hypertension, osteoarthritis, and 2 years ago was diagnosed with acute renal failure of unknown cause.

A widower, the patient is retired, lives alone, and says he drinks one to two beers per day. He quit smoking 10 years ago. He denied illicit drug use. His past surgical history includes radioactive seed implant for prostate cancer 2 years ago and arthroplasty of the right knee for osteoarthritis 1 year ago.

In addition to the leuprolide and bicalutamide, he takes 81 mg of aspirin daily, 0.8 mg of tamsulosin at night, and 5 mg of amlodipine daily.

The patient was alert and oriented but appeared to be in moderate distress and had his right hand placed over his low back. His cardiac rate and rhythm were regular without murmurs, and his lungs were clear to auscultation with no crackles or wheezes.

No palpable masses or organomegaly were noted on abdominal examination. The patient had difficulty assuming the supine position due to pain. He was able to forward flex his trunk to 80 degrees with minimal discomfort, and had no limitation of motion on extension of his trunk or lateral bending. He had mild tenderness to palpation in the lower thoracic and upper lumbar spine paraspinal muscles.

On neurologic examination, he had intact sensation to both lower extremities with good muscle strength and no visible atrophy of lower extremity musculature. Deep tendon reflexes were 2+ bilaterally in the patellae and ankles.

Plain radiographs of the lumbar and thoracic spine showed multilevel osteoarthritic changes with compression fractures of the T-11 and T-12 vertebrae. Osteopenia was noted but no lytic or blastic lesions were identified.

The patient was advised to continue taking acetaminophen plus codeine as needed for pain and to continue with local heat and rest as needed. A bone scan was scheduled and he was scheduled for physical therapy two times a week for 1 month.

At a follow-up visit 2 weeks later, the patient stated that his symptoms were unchanged although opioid analgesia reduced his pain from an 8 to a 4 on a 0-to-10 pain intensity rating scale. Physical therapy had produced minimal improvement. The bone scan showed osteoporosis of the lumbar spine with osteopenia of both hips.

The patient was prescribed alendronate 70 mg/week and calcium carbonate 500 mg twice daily along with vitamin D 800 units daily. He was advised to stop the acetaminophen plus codeine and was prescribed 10 mg of hydrocodone with 325 mg of acetaminophen to be taken every 4 to 6 hours as needed for pain.

Two weeks later on follow-up, the patient's condition remained unchanged. An MRI of lumbar and thoracic spine was ordered along with a complete blood cell count, erythrocyte sedimentation rate (ESR), rheumatoid factor, antinuclear antibodies, and complete metabolic panel. The MRI showed T-11 and T-12 vertebral compression fractures and moderate height loss at the T11 level. Edema in both vertebral bodies suggested acute compression fracture. Laboratory results were all normal except for the ESR, which was elevated at 108 mm/hour (normal value, less than 10 mm/hour).

The patient was referred to a rheumatologist who repeated the ESR and also tested the patient's HLA B-27, cyclic citrullinated protein antibody (CCP), and antineutrophil cytoplasmic antibodies (ANCA). The rheumatologist noted an ESR of 93 mm/hour but all other laboratory tests were normal. The rheumatologist then tested the patient's serum protein electrophoresis, which was abnormal with monoclonal gammopathy.

The patient was referred to hematology/oncology for a bone marrow biopsy, which showed an IgA kappa-restricted plasma cell population in 3% of the total cells. The bone marrow biopsy was positive for CD38 and the immunohistochemical analysis showed marrow plasmacytosis in 75% of total cells. A bone survey showed no lucent lesions, suggesting multiple myeloma; osteopenia and multiple compression fractures also were noted.

The patient was diagnosed with multiple myeloma with plasma cell dyscrasia, IgA kappa. The oncologist discussed all the treatment options with the patient and the patient chose oral chemotherapy and was placed on lenalidomide and prednisone.

The patient's presenting symptoms did not suggest mechanically induced back pain as he had no history of trauma or injury. His pain was exacerbated at night while resting and when turning in bed. The pain started insidiously and gradually worsened over a period of 2 months.

Low back pain is a common complaint among adults in the United States, with more than 26% reporting back pain lasting at least 1 day in the past 3 months.1 Most patients with low back pain can be treated successfully with conservative therapy. If no improvement occurs within 6 weeks, a more extensive workup is necessary.2 Routine imaging for low back pain does not improve clinical outcomes and may expose the patient to unnecessary harm.3

A more extensive workup is needed if the clinician notes any red flags in the patient's history and physical examination, including:2

The patient was receiving androgen deprivation therapy for prostate cancer, which put him at an increased risk for osteoporosis-related fracture.4 The results of the bone scan along with thoracic, lumbar sacral spine radiographs, and MRI results were consistent with osteoporotic compression fracture.

The patient's past medical history of prostate cancer raised concerns about metastatic prostate cancer to the vertebrae. The most common site of distant prostate metastasis is the bone; lumbar vertebrae are most commonly involved.5 Metastatic prostate cancer to the bone is osteoblastic and this patient's radiographs showed osteopenic and osteoporotic changes.

Laboratory findings of an elevated ESR suggested an inflammatory condition or malignancy. The rheumatologist failed to find a rheumatologic cause for the elevated ESR. Further testing included a serum electrophoresis that suggested multiple myeloma as the cause of the elevated ESR and compression fractures. The diagnosis was confirmed by bone marrow biopsy.

Multiple myeloma is a plasma cell malignancy that produces excessive immunoglobulin chains, typically IgG, IgA, light chains, or Bence Jones proteins.6 The overproduction of plasma cells can cause bony destruction and produce osteolytic lesions and osteopenia that can result in pathological fractures. The most common presenting symptoms in multiple myeloma include anemia, bone pain, elevated creatinine, fatigue or weakness, hypercalcemia, and unintended weight loss.6 The median age of diagnosis for multiple myeloma is 70 years. Laboratory evaluation includes protein electrophoresis and bone marrow biopsy. The disease remains incurable but sustained remission is possible with current therapy.

Back pain is a common presenting symptom in primary care. Most patients with back pain do not require extensive workup and their clinical course is usually uncomplicated. The decision to initiate a detailed diagnostic workup should be guided by a focused physical examination and a detailed history. Awareness of the red flags in a patient's history and physical examination can help to identify patients who need a more extensive laboratory and radiologic evaluation.

1. Deyo RA, Mirza SK, Martin BI. Back pain prevalence and visit rates: estimates from U.S. national surveys, 2002. Spine. 2006;31(23):2724–2727. Ovid Full Text Bibliographic Links [Context Link]

2. Patel ND, Broderick DF, Burns J, et al. ACR appropriateness criteria low back pain. https://acsearch.acr.org/docs/69483/Narrative. Accessed March 1, 2016. [Context Link]

3. Chou R, Qaseem A, Owens DK, Shekelle P. Diagnostic imaging for low back pain: advice for high-value health care from the American College of Physicians. Ann Intern Med. 2011;154(3):181–189. [Context Link]

4. Smith MR. Androgen deprivation therapy for prostate cancer: new concepts and concerns. Curr Opin Endocrinol Diabetes Obes. 2007;14(3):247–254. Ovid Full Text Bibliographic Links [Context Link]

5. Tombal B, Lecouvet F. Modern detection of prostate cancer's bone metastasis: is the bone scan era over. Advances in Urology. 2012, article 893193. www.hindawi.com/journals/au/2012/893193. Accessed March 1, 2016. [Context Link]