# Efficacy and Cost-Effectiveness of MDM2 Fluorescence In Situ Hybridization (FISH) in Morphologically Atypical Spermatic Cord Lipomas

## TL;DR

This study shows that MDM2 FISH testing can help distinguish rare liposarcomas from benign lipomas in spermatic cord tissue during hernia repairs.

## Contribution

The study evaluates the diagnostic accuracy and cost-effectiveness of MDM2 FISH in atypical spermatic cord lipomas.

## Key findings

- Only 2.3% of atypical spermatic cord lipomas tested positive for MDM2 amplification, indicating liposarcoma.
- 97.7% of cases had reactive-type atypia with negative FISH results, confirming benign lipomas.
- The authors suggest using FISH testing for lesions larger than 10 cm to avoid misdiagnosis.

## Abstract

Background: Spermatic cord lipomas originate from preperitoneal adipose tissue within the internal spermatic fascia and are found in 20%-70% of all inguinal hernia repairs. Morphologically, spermatic cord lipomas may harbor some atypical features, including increased stromal cellularity with thickened fibrous bands, occasional lipoblasts, and stromal nuclear atypia or hyperchromasia, raising concern for well-differentiated liposarcoma (WDLS) versus reactive-type atypia. Fluorescence in situ hybridization (FISH) for MDM2 amplification would be the gold standard test in such cases. The aim of this study was to evaluate the efficacy and cost-effectiveness of MDM2 FISH in diagnostically discrimination morphologically atypical spermatic cord lipoma cases at our institution.

Methods: All cases with “specimen type” labeled as “spermatic cord lipoma” between 2018 and 2023 were retrospectively retrieved from our institutional archives. Cases were included in the study group if they had MDM2 FISH performed. Cases with a prior history of spermatic cord well-differentiated liposarcoma with positive MDM2 amplification were excluded. MDM2 amplification status and corresponding final diagnosis were recorded.

Results: Three hundred twenty specimens labelled as spermatic cord lipoma were retrieved from our archives. Forty-three out of 320 had MDM2 FISH performed. All 43 cases demonstrated atypical features and appeared morphologically similar. Only one out of 43 (2.3%) cases demonstrated a positive MDM2 amplification result, thus labeling it as an incidental WDLS (11 cm) in the setting of an inguinal hernia repair for which the patient required a subsequent orchiectomy. The remaining 42 cases (97.7%) harbored reactive-type atypia with negative FISH results and were diagnosed as spermatic cord lipomas.

Conclusion: Our results indicate that 2.3% of morphologically atypical specimens labeled as spermatic cord lipoma at our institution are in fact well-differentiated liposarcomas. These findings prove the efficacy of MDM2 FISH in diagnosing WDLS in the setting of atypical spermatic cord lipoma labeled specimens. Although 97.7% of our spermatic cord lipomas harbored reactive-type atypia with negative FISH results, which argues against the cost-effectiveness of such testing, we propose performing FISH analysis in cases greater than 10 cm in size to avoid misdiagnosis and ensure optimal patient care.