Macro - A relatively uniform, firm, white nodule, 9 x 8 x 7mm, arising from the visceral layer of the tunica vaginalis and protruding into the testis. The adjacent normal tan testicular parenchyma is present for comparison.
Micro (low power) - Section of tumour (right) with adjacent normal testis (left - rounded spaces are seminiferous tubules). The tumour can be seen arising from the thick visceral layer of tunica vaginalis and is stroma rich, accounting for the firmness clinically.
Micro (high power) - The tumour is composed of rounded to elongate epithelial lined spaces. The spaces have some resemblance to vessels but the lining cells are positive for epithelial and mesothelial markers on immunohistochemistry. The surrounding stroma is dense.