Testes : Plasmacytoma
Like lymphoma, plasmacytoma has an interstitial growth pattern with preservation of seminiferous tubules. Plasmacytomas may involve testis or epididymis in the setting of generalized multiple myeloma or may occur as isolated tumors. They may be mistaken for spermatocytic seminoma, anaplastic seminoma, or lymphoma (Ferry JA, Young RH, Scully RE. Am J Surg Pathol 1997 May; 21(5):590-8..