277 Large Paratesticular Liposarcoma With High- and Low-Grade Dedifferentiation Mimicking Inguinal Hernia.

Paratesticular liposarcomas are rare neoplasms that comprise 3%-7% of all testicular sarcomas and usually arise in the adipose tissue of the spermatic cord or by malignant transformation of a pre-existing lipoma. These entities can be challenging to diagnose since oftentimes, they mimic benign conditions such as hernia, cystic lesions, and subcutaneous lipomas. We present the case of a 70-year-old man with a one-year history of inguinal discomfort and a slow-growing, painless mass of the left testis. A testicular ultrasound was performed, which revealed a vascular lesion initially thought to be an omental hernia, which was followed with a CT scan that showed a mass less likely to be a hernia but suspicious for testicular malignancy. The patient underwent a left orchiectomy and was diagnosed as having dedifferentiated liposarcoma in a background of well-differentiated liposarcoma of the sclerosing type. The mass measured 30.2 cm in maximum dimension and revealed both low- as well as high-grade dedifferentiation. Dedifferentiation has been described very rarely in the genitourinary region and occurs in approximately 10 % of well-differentiated liposarcomas, confers a poorer prognosis, and increases the rates of local disease recurrence and metastasis. Although traditionally, tumors with both high- and low-grade dedifferentiation were considered to be equally aggressive, current literature suggests that high-grade dedifferentiation has a worse prognosis as compared to low-grade dedifferentiation. Thorough evaluation of scrotal masses, a high level of suspicion aided by imaging studies and documentation of the type of dedifferentiation in histopathology reports are essential in the diagnosis and appropriate management of these uncommon lesions. [ABSTRACT FROM AUTHOR]