PMC5836420_01
Histological examination of the left-sided testicular mass. Two distinct masses are identified. (a) The classic seminoma with clear cell morphology (depicted by the blue arrows) is on the top and the circumscribed Leydig cell tumor is at the bottom (black arrows) (hematoxylin and eosin (H&E), x250). On higher magnification, (b) the seminoma cells contain abundant clear cytoplasm and slightly hyperchromatic nuclei (H&E, x4000). (c) The Leydig cell tumor is composed of polygonal cells with prominent nucleoli with eosinophilic, granular, and vacuolated cytoplasm (H&E, x4000).
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fig1
Both masses were found alongside each other with intervening fibrous septa (Figure 1(a)). Histological sections of the first mass (Figure 1(b)) showed nests of tumor cells with clear cytoplasm with intervening fibrous bands and lymphocytes, which was consistent with a provisional diagnosis of seminoma. Microscopic examination of the small nodule (Figure 1(c)) revealed polygonal cells with eccentric nuclei, eosinophilic, granular, and vacuolated cytoplasm, mild atypia, and rare mitosis, which was consistent with a tentative diagnosis of a Leydig cell tumor.
Immunohistochemical staining of the seminoma and Leydig cell tumor. (a) The seminoma cells (top) stained positively for (a) CD117 and (b) PLAP, while the Leydig cell tumor (bottom) was negative for both markers. (c) Inhibin immunostain is positive in the Leydig cell tumor (bottom) and negative in the seminoma (top). (d) Both the seminoma (top) and Leydig cell tumor (bottom) are negative for cytokeratin (x4000 each).
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fig2
On immunohistochemistry, neoplastic cells from the large mass were positive for CD117 (Figure 2(a)), placental alkaline phosphatase (PLAP) (Figure 2(b)), and CD10 and negative for inhibin (Figure 2(c)), cytokeratin (Figure 2(d)), beta-catenin, smooth muscle actin (SMA), synaptophysin, desmin, S100, beta-HCG, and alpha-fetoprotein.