PMC6800931_01
Gross and representative H&E images. Gross findings showed a tan-red, hemorrhagic, well-circumscribed circular mass with focal areas of tan-white friable necrosis (a). At low power, diffuse, solid sheets of densely packed neoplastic cells infiltrating the testicular parenchyma, hilar soft tissue, epididymis, and spermatic cord (b-d) with sparing of the seminiferous tubules (e) were seen. At high power (f-h), medium-sized neoplastic cells showed blastoid morphology, scant agranular cytoplasm, irregular nuclei with fine to vesicular chromatin, and small nucleoli. Increased mitotic activity with atypical mitotic figures, areas of necrosis, and abundant apoptotic debris were seen.
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On gross examination, the testicular mass was serially sectioned to reveal a tan-red, hemorrhagic, well-circumscribed circular mass (5.0 x 4.0 x 3.4 cm) with focal areas of tan-white friable necrosis (Figure 1(a)). Histologically, the testicular mass showed diffuse, solid sheets of densely packed neoplastic cells infiltrating the testicular parenchyma, hilar soft tissue, epididymis, and spermatic cord (Figures 1(b)-1(d)) with sparing of the seminiferous tubules (Figure 1(e)). The tumor exhibited increased mitotic activity with atypical mitotic figures, areas of necrosis, and abundant apoptotic debris (Figures 1(f)-1(h)).
Representative immunohistochemistry images. Initial IHC panel of CD3 (a), CD20 (b), and SALL4 (c), was negative and argued against a diagnosis of lymphoma, primary germ cell tumor, or epithelial neoplasm. The neoplastic cells were weakly positive for CD45 (d), and granularly positive for CD68 (e), with dot-like pattern. Ki-67 (f), was expressed in 80% of cells. The diagnosis of BPDCN was consistent with positive CD4 (g), CD56 (h), and weak CD123 (i).
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A preliminary immunohistochemistry (IHC) panel of CD3, CD20, AE1/AE3, and SALL4 was performed (Figures 2(a)-2(c)). To further characterize the neoplasm, a second IHC panel of CKIT, CD45, CD68, S100, Ki-67, and CD138 was performed (Figures 2(d)-2(f)). Subsequently, a third IHC panel of CD4, CD56, and CD123 was performed (Figures 2(g)-2(i)).