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Routine MDM2 FISH Testing and Preoperative Biopsy Reduces Recurrence Rate of Atypical Lipomatous Tumours
Samuel O H Ching1, Anderson S M Leung2, Raymond C H Yau2
1Department of Pathology, School of Clinical Medicine, LKS Faculty of Medicine, Queen Mary Hospital, The University of Hong Kong, Hong Kong SAR, China.
Background:
Although MDM2 FISH test has been increasingly used to differentiate ALT and benign lipomatous tumours, its impact on clinical outcome remains underexplored. This study investigated whether routine MDM2 FISH testing on preoperative biopsy is associated with a reduction in the recurrence risk of ALT.
Methods:
A total of 336 patients with MDM2-verified well-differentiated lipomatous tumours (ALT, n = 67; lipoma, n = 269) treated at a tertiary sarcoma centre were retrospectively analysed. Clinicopathological parameters, histological-molecular concordance, pre-operative diagnostic approach and recurrence rates were compared.
Results:
Compared to benign lipomatous tumours, ALT patients were older (p = 0.002), had larger tumours (median 15.0 vs 7.0 cm, p < 0.001) and more frequently deep extremity lesions (p < 0.001). Up to 25% of biopsy specimens of ALT exhibit purely benign morphology. ALT patients who underwent preoperative biopsy with MDM2 FISH had a lower recurrence rate than those who did not (16.2% vs 56.7%, p < 0.001). This was associated with a higher rate of extracapsular excision (97.3% vs 71.4%-77.8%, p = 0.021).
Conclusion:
Routine MDM2 FISH testing on preoperative biopsy provides a definitive diagnosis of ALT, especially for lipoma-like histology, enabling surgeons to plan extracapsular excision and thereby reducing local recurrence.
