Tumors of the scapula: A retrospective analysis identifying predictors of malignancy

Background: Osseous tumors of the shoulder girdle occur most frequently in the proximal humerus, scapula and clavicle. Prior studies have determined that tumors occurring in the scapula have a higher risk of malignancy, but few have looked exclusively at tumors of this site to describe incidence, clinical features and potential predictors of malignancy. As imaging technologies for diagnosis have improved, it is important to re-evaluate if patterns of incidence have changed and if new imaging findings could potentially be predictors of malignancy.

Methods: This retrospective analysis identified 173 patients from a pediatric and an adult hospital between 1990 and 2015. All patients with tumors of the scapula either of bony origin or with bony invasion were included. Diagnosis, tumor location, and patient demographics were collected. Bivariate and logistic regression analyses were performed to identify potential predictors of malignancy.

Results: Chondrosarcoma and osteochondroma were the most common malignant and benign tumors, respectively. Benign tumors were more prevalent in the pediatric population. Tumors occurred most frequently in the body of the scapula. Risk for malignancy increased with age (OR 1.09, 95% CI 1.05-1.12), tumors invading multiple sites (OR 10.85, 95% CI 2.37-49.72) and tumors that were lucent (OR 7.02, 95% CI 1.14-43.21) or had a mixed radiographic appearance (OR 11.47, 95% CI 1.36-99.65).

Conclusions: Including neoplasia in the differential diagnosis for shoulder complaints is important because the scapula is a site of increased risk of malignancy. Patterns of incidence and prevalence have not changed in the last years with the use of more advance techniques of imaging studies. Older age, lucent or mixed imaging, and tumors that span multiple sites of the scapula were found to be predictors of malignancy. Additional cross-sectional anatomy studies may be warranted for further evaluation in patients presenting with these characteristics given the higher concern for malignant disease.

Level of evidence: Level IV, Prognostic Study.