Presumptive Late-Onset Ankylosing Spondylitis Simulating Osteoblastic Skeletal Metastasis in a Patient With a History of Prostate Carcinoma: A Diagnostic Challenge

Objective: The purpose of this report is to present a presumptive case of ankylosing spondylitis with late stage progression that simulated osteoblastic metastasis in a patient with a history of prostate carcinoma. Clinical Features: A 67-year-old white man presented to a chiropractic clinic complaining of severe and worsening acute low back pain and right foot "numbness." Further questioning also revealed a history of prostate carcinoma. Intervention and Outcome: Imaging examination revealed a sclerotic pedicle and increased uptake of radiopharmaceutical on a nuclear medicine bone scan highly suggestive of osteoblastic skeletal metastasis. Further evaluation, however, revealed that the bone sclerosis was not the result of skeletal metastasis, but more consistent with a seronegative spondyloarthritis such as ankylosing spondylitis. Conclusion: This report describes a presumptive case of ankylosing spondylitis simulating skeletal metastasis in a patient with a past medical history of prostate cancer. This atypical presentation illustrates the inherent uncertainty of diagnosis and how that uncertainty can be challenging in clinical practice. It also reinforces that it is critical for healthcare providers to consider a wide spectrum of differential diagnoses to avoid misdiagnoses and inappropriate interventions. (C) 2015 National University of Health Sciences.