The testicular tissue is nearly completely replaced by diffuse
infiltration of large atypical cells. Rare residual seminiferous
tubules are present with interstitial infiltration of tumor cells.
The tumor cells are large with moderate to abundant cytoplasm, large
and variable nuclei. Prominent nucleoli are seen in some tumor
cells. Apoptosis and mitosis are common. The tumor is largely
confined by the tunica albuginea and focally invades into fat
tissue. The spermatic cord resection margin is positive for the
The tumor cells are
positive for CD45, CD20, CD79a, CD5, Bcl-2 and BCL-6, but negative
for CD3, CD10, CD30, NSE and PLAP. Nearly 100% of the tumor cells
are positive for Ki-67.
A clonal Immunoglobulin Heavy chain gene rearrangement is detected
by DNA amplification. An extra copy of IgH with a deletion of the 5'
(telomeric) portion is present in 89% of the interphase cells from
this tissue section. Additional studies were negative for
rearrangements of the CMYC (8q24) region in this tissue section.