Factors impacting tumor displacement artifact and pseudo-lymphovascular invasion in testicular germ cell tumors.

Abstract

Testicular germ cell tumors are susceptible to tumor displacement artifact (TDA), which produces pseudo-lymphovascular invasion (LVI) and confounds the identification of true LVI. Our study aimed to evaluate tumor displacement artifact and pseudo-LVI in testicular germ cell tumors and determine if prolonged fixation improves histological quality. A retrospective search identified 121 orchiectomies with slides that were reviewed to assess TDA and pseudo-LVI. Seminoma had more TDA (68% vs 45%, P = .01) and pseudo-LVI (53% vs 19%, P < .001) than mixed germ cell tumor. Seminoma and mixed germ cell tumor with TDA and pseudo-LVI were larger than those without. Mixed germ cell tumor with ≥50% composition of seminoma had a higher rate of TDA (89% vs 38%, P = .008) and pseudo-LVI (44% vs 15%, P = .06) than those with less. TDA was reduced in seminoma with >1 night fixation compared to no fixation (50% vs 82%, P = .046), with a similar trend in mixed germ cell tumor (31% vs 60%, P = .15). A trend in reduction of pseudo-LVI was seen with >1 night fixation compared to no fixation in seminoma (64% vs 39%, P = .12). Seminomas and larger germ cell tumors were more prone to TDA and pseudo-LVI. Prolonged formalin fixation improved histological quality in testicular germ cell tumors. Based on these data, we recommend fixation for at least 2 nights before sectioning orchiectomy specimens, particularly for larger tumors.