Magnetic resonance imaging (MRI) shows high sensitivity for detecting metastatic bone tumors, but distinguishing metastasis from benign lesions is sometimes difficult. We report a case of hyperplastic hematopoietic bone marrow mimicking metastasis. Different radioisotopes in nuclear imaging clarified multiple bone lesion pathophysiologies.
A 59-year-old woman with no medical history presented with a 6-month history of a tingling sensation in her toes. She lost her balance while walking and experienced frequent falls. She was a heavy smoker and reportedly drank 4 to 5 glasses of Japanese distilled spirits daily. Neurologic examination revealed no remarkable muscle weakness, with bilaterally symmetrical strength (5/5) and decreased Achilles tendon reflexes. Sensation in her lower extremities was diminished. She showed a wide-based gait and a positive Romberg sign. Laboratory studies revealed mild liver abnormalities and macrocytic changes in red blood cells.
On the basis of her drinking habits, we suspected vitamin B12 deficiency as the cause of her symptoms and conducted brain and cervical MRI. Although there was no evidence of a parenchymal lesion, both T1- and T2-weighted images revealed multiple focal low signal intensity areas in the skull and vertebral bones. Multiple metastatic bone tumors were strongly suspected. Bone scintigraphy using technetium-99m showed significant uptake points in the skull, spine, and costal bones, indicating multiple bone metastases. However, whole-body computed tomography (CT) and endoscopic examinations revealed no evidence of the malignant primary site. 18F-fluorodeoxyglucose positron emission tomography/CT indicated low-level 18F-fluorodeoxyglucose accumulation in the vertebral bones, but it did not detect the origin of the suspected metastatic bone tumors. We performed a CT-guided biopsy of the 12th vertebra that had the highest 18F-fluorodeoxyglucose accumulation among the involved vertebral bones. The tissue diagnosis established the presence of hyperplastic hematopoietic bone marrow. Encouraging the patient to stop drinking alcohol led to recovery from her neurologic symptoms, suggesting that alcoholic neuropathy was the cause of her initial symptoms. At 18 months since her initial visit, she is continuing to do well.
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-Tatsuya Sato, MD, Junwa Kunimatsu, MD, Riri Watanabe, MD, On Kato, MD
This article originally appeared in the March 2016 issue of The American Journal of Medicine.
