An epidemiological review of 623 foot and ankle soft tissue tumours and pseudo-tumours.

Background: In evaluating foot and ankle soft tissue masses, comprehensive epidemiological data, especially clinical predictors of malignancy, is essential knowledge. Our aim was to assess these data in a cohort of patients that have undergone surgical excision of foot and ankle soft tissue tumours and pseudo-tumours over a 10-year period.
Methods: A retrospective review of foot and ankle soft tissue tumours and pseudo-tumours excised in a tertiary hospital from 1 Jan 2006 to 31 Dec 2016 was performed. Uni- and multivariable analyses via logistic regression were conducted for all independent variables to identify their relationship with malignancy. Applying receiver operating characteristic (ROC) curves and Youden's Index to significant variables, we attempted to identify optimal threshold values to predict malignancy of the soft tissue mass.
Results: A total of 623 tumours and pseudo-tumours were analysed, and majority were benign (n = 605, 97.1%). The most common pseudo-tumour, benign, and malignant tumours were ganglion cysts (n = 289, 90.3%), plantar fibromas (n = 54, 18.9%) and pleomorphic undifferentiated sarcomas (n = 4, 22.2%), respectively. Increasing age (P = 0.036), larger size of mass (P < 0.001) and male gender (P = 0.017) were significant predictors of malignancy. ROC and Youden's Index analyses identified optimal threshold values of 4.0 cm (area under curve [AUC] = 87.6%) for size of mass and 66 years (AUC = 60.7%) for age.
Conclusion: Majority of foot and ankle soft tissue masses are benign. Increasing age, larger size of mass and male gender are significant predictors of malignancy. The threshold value in predicting malignancy is 4.0 cm for size of mass and 66 years for age.
(Copyright © 2020 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.)