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The Case Files: A Patient with Not-So-Benign Low Back Pain

Chung, Arlene S. MD; Raukar, Neha P. MD

doi: 10.1097/01.EEM.0000442778.13197.f9
The Case Files

Dr. Chung, left, is a medical education fellow at Maimonides Medical Center and was previously a member of the department of emergency medicine at Warren Alpert School of Medicine. Dr. Raukaris an assistant professor and the director of sports medicine in the department of emergency medicine at Warren Alpert School of Medicine and a consulting physician at Brown University Athletics.





A 20-year-old man with a history of schizophrenia and polysubstance abuse presented to the ED complaining nonradiating, left-sided low back pain for one week. He denied any trauma, inciting event, intravenous drug use, tuberculosis exposure, or prior history of back pain or surgery. He also denied systemic symptoms such as fevers, sweats, abdominal pain, nausea, vomiting, leg pain, or difficulty walking.

He was taking risperidone and lithium, smoked a pack of cigarettes a day, did not drink alcohol, and occasionally used marijuana. Family history was negative for malignancy. Vital signs remained within normal limits during the course of his visit. Physical exam was notable only for tenderness to palpation over the soft tissues of his left lower back. He had negative bilateral straight leg raises and no appreciable motor or sensory deficits. Plain radiographs of his lumbar spine were unremarkable. Urinalysis was normal, and was specifically negative for blood and nitrites. Erythrocyte sedimentation rate (ESR) was 15 mm/hr. The patient was discharged home with a diagnosis of acute low back pain and a prescription for tramadol.

The patient's next two visits to the ED were for complaints unrelated to his low back pain. He had a CT scan of his abdomen and pelvis for gastrointestinal symptoms, which was normal with no other pathologies identified. The patient was discharged home after both visits.

The patient presented nine more times to the ED during the subsequent eight weeks with the complaint of low back pain. During this time, the distribution of pain progressed to include his right and left lumbar region. The pain radiated farther down his left leg and finally extended to the ankle. He developed a positive straight leg raise at 30 degrees on the left side. He was alternately prescribed muscle relaxants, ibuprofen, and narcotic pain medications for his symptoms. His history also includes one visit in which he left against medical advice and one visit in which he left without being seen by a physician. His discharge diagnoses were chronic back pain and sciatica.

Nine months after the patient's initial visit, on his 12th presentation, he complained of pain that awakened him. He also complained of constipation, mild abdominal pain, and pain radiating to his left testicle. The patient had nontender lumbar vertebrae, but notable pain with palpation over the left posterior superior iliac spine and also pain with flexion, abduction, and external rotation of his hip and sacroiliac joint on the left side. He did not have tenderness over the piriformis muscle, but complained of tenderness over the surrounding tissues. The use of Waddell's signs to suggest malingering or psychological components of his back pain did not elicit any positive responses from the patient.

Laboratory data demonstrated a normal complete blood count, a normal urinalysis, and an ESR of 54 mm/hr. A repeat set of lumbar radiographs with the addition of pelvic radiographs demonstrated sclerotic and lytic lesions within the medial aspect of the left iliac bone. Given the abnormal radiographs, MRI of the pelvis was performed and revealed extensive abnormal signal intensity involving the ilium and sacrum as well as the left gluteus maximus and medius muscles, left erector spinae, and left piriformis. Chest CT showed pulmonary nodules suggestive of metastatic disease. The patient was admitted with a presumptive diagnosis of malignancy, likely Ewing's sarcoma or osteosarcoma. Early during the course of his hospitalization, the patient underwent CT-guided biopsy of his lesions. Pathology revealed a malignant neoplasm most consistent with Ewing's sarcoma based on morphology, immunohistochemical staining, and fluorescence in-situ hybridization analysis.

Multiple physicians failed to identify a life-threatening diagnosis. The patient had a classic presentation for Ewing's sarcoma, which most often manifests as pain involving the pelvic region in young males. (J Neurosurg Spine 2011;14:[2]:143; J Orthop Sci 2001;6:[4]: 366.) According to the SEER database, the incidence of Ewing's sarcoma is approximately three cases per 1,000,000 children and adolescents (J Pediatr Hematol Oncol 2008;30[6]:425), and represents the second most common primary malignancy of bone in patients less than 20 years of age. Unfortunately, delays in diagnosing Ewing's sarcoma are common, with some studies citing intervals more than six months from initial presentation to diagnosis. (J Am Acad Orthop Surg 2010;18[2]:94.) Prognosis depends on the site of primary tumor and extent of metastases. Pulmonary involvement has a slightly better prognosis compared with other organ systems, although any metastasis has a survival rate approximately half the rate of localized disease. (J Am Acad Orthop Surg 2010;18[2]:94.)

Low back pain continues to present many challenges for emergency physicians. Patients presenting for secondary gain commonly use the complaint of low back pain to obtain narcotic pain medications because few objective findings exist to reliably identify nonorganic etiologies. Waddell et al classically described a set of eight signs grouped into five categories that could help the physician differentiate organic from psychogenic back pain in 1980. Subsequent studies using Waddell's signs have shown an association between depression, anxiety, and somatization with nonphysiologic findings. (Pain Physician 2003;6:[2]:159.)

Croskerry has described a number of error-producing conditions that predispose to misdiagnosis. (Acad Emerg Med 2007;14[8]:743.) The patient's comorbid psychiatric illness and multiple prior presentations for the same complaint of low back pain in this case likely caused several cognitive biases such as cueing, search satisfaction, and fundamental attribution error that led to a delay in diagnosis and progression to pulmonary metastastic disease. Atraumatic back pain is typically a benign complaint in the ED that does not require extensive diagnostic workup. Emergency physicians should be aware of red flags in patients who present with low back pain, including rapidly progressive signs and symptoms, failure to improve with therapy, pain persisting for more than more weeks, night pain, or pain at rest.

© 2014 by Lippincott Williams & Wilkins