MUSCULOSKELETAL PAIN AS AN INDICATOR OF OCCULT MALIGNANCY - YIELD OF BONE-SCINTIGRAPHY

Background: When musculoskeletal pain is persistent or out of proporti on to clinical findings, diagnostic imaging is often used to evaluate for the presence of occult pathologic conditions. Objective: To examin e the efficacy of bone scintigraphy for identifying occult malignancy in such patients. Methods: Bone scans of 491 patients with new or recu rrent complaints of musculoskeletal pain and no previously known malig nancy were retrospectively reviewed. The findings of each scan were cl assified into 1 of the following categories: (A) no evidence of malign ancy; (B) equivocal (1-3 lesions of uncertain significance); or (C) pr obable metastatic disease (>3 lesions without trauma or other benign e xplanation). All diagnoses of malignancy established within 6 month of the bone scan were then determined from review of radiological and cl inical records. Results: The distribution of scan interpretations was as follows: category A, 386 (79%); category B, 84 (17%); and category C, 21 (4%). Among the 181 patients younger than 50 years, 161 (89%) ha d category A and 20 (11%) had category B scans. Of the 310 patients ag ed 50 years or older, 226 (73%) had scans in category A, 64 (21%) in c ategory B, and 21 (7%) in category C. Thirty patients (6%) had maligna ncy involving bone, 29 among those aged 50 years or older, In patients aged 50 years or older, 10 (16%) of 64 with equivocal scan findings ( category B) and 19 (90%) of 21 with widespread abnormalities (category C) had malignancy involving bone. Initial radiographs of symptomatic sites showed lyric or blastic bone abnormalities suggestive of maligna ncy in 16 (59%) of the 29 older patients in whom this diagnosis was co nfirmed. Conclusions: In patients aged 50 years or older, the yield of bone scintigraphy for identification of occult malignancy (29/310; 9% ) is sufficient to justify its use in the investigation of the cause o f problematic bone or musculoskeletal symptoms.