Clinical significance of solitary rib hot spots on bone scans in patients with extraskeletal cancer: Correlation with other clinical manifestations

Purpose: Bone scans showing solitary hot spots in the ribs pose diagnostic problems in patients with proved extraskeletal cancers. The authors wanted to determine the importance of solitary rib lesions and their correlation with other clinical manifestations. Materials and Methods: The study included 199 patients with solitary rib hot spots on their bone scans. The follow-up radiographic and scintigraphic images were reviewed to determine their origin. The correlation between the occurrence of a malignant rib lesion and clinical data were determined using Pearson chi-square tests. Results: Ninety-three patients had an established cause of the rib hot spot. Eleven (11.8%) had a solitary malignant rib hot spot and 82 (88.2%) had a solitary benign rib hot spot. None of the hot spots at costochondral junctions were malignant. Of the 11 patients with proved metastatic rib hot spots, 1 of 11 (9.1%) had localized bone pain, 5 of 6 (83.3%) were concordant with primary tumors, 4 of 7 (57.1%) had elevated tumor markers, and 5 of 11 (45.5%) had concurrent extraskeletal metastases. For the 82 patients with benign rib hot spots, the figures were 2 of 82 (2.4%), 43 of 57 (75.4%), 26 of 69 (37.7%), and 19 of 82 (23.2%), respectively. Statistical analysis did not show a significant correlation between the incidence of metastases in solitary rib hot spots and clinical manifestations. Conclusions: Most solitary rib hot spots on bone scans were benign. The interpretation of a solitary hot spot in the ribs is difficult even with the help of these clinical manifestations. Follow-up bone scintigrams or radiographs are needed for further investigation of solitary rib hot spots.