Serous Borderline Tumor : Microinvasion
Microinvasion in Serous Borderline Tumor (SBT) of the Testis: Small foci (< 5 mm) of microinvasion (not shown here) are acceptable within the spectrum of SBT. These foci consist of irregularly arranged clusters of cells or isolated tumor cells in the subepithelial stroma. The cells have a low Ki-67 labeling index and don't worsen the prognosis significantly. SBT arising in testis do not metastasize or recur after resection (McClure RF et al. Am J Surg Pathol 2001 Mar; 25(3):373-8.