Management Algorithm for Atypical Lipomatous Tumours: A Retrospective Case Series.

Introduction: Atypical lipomatous tumours (ALTs), or low-grade well-differentiated liposarcomas (WDLs), can be identified using radiological complex septations and histological atypia. In our view, this is a confusing name that underestimates the risk of local recurrence of such tumours. Defining a management algorithm for differentiating a lipoma from an ALT is important for considering the best management of these patients.

Aims: This study aims to evaluate the clinical, radiological, and histological features of ALT presentation and propose a management algorithm for these lesions.

Methods: A retrospective case series of a prospectively maintained database at Tallaght University Hospital, Dublin, Ireland was carried out on all patients with ALTs from 2013 to 2019. The group demographics, tumour characteristics, radiological features, treatment, and recurrence were described.

Results: From 2013 to 2019, 607 lipomatous tumours were resected; 40 lesions in 37 patients were classified as ALTs. The mean age of this subgroup of patients was 56.15 ± 13.64 years (range: 25-83 years). The most common location was the lower limb. All patients underwent clinical, radiological, and histological workups prior to surgery. Angio-embolisation prior to surgery was required in two (5%) patients; three (7.5%) patients developed local recurrence requiring a second surgical resection. Characteristics of ALTs and a management algorithm are proposed.

Conclusion: It is important for a practitioner to differentiate a suspected ALT from a lipoma. Increased intratumoural vascularity and septation in ALT are reflected in the MRI findings and may play a key role in the acquisition of a malignant phenotype in adipocytic tumours. The proposed management algorithm for these lesions aims to help stratify these subcutaneous lesions.