Signet ring cell lymphoma in salivary gland. An immunohistochemical and ultrastructural study

A case of recurrent signet ring cell lymphoma involving a salivary gland is reported. The tumour was centroblastic-centrocytic nodular and diffuse. The cells were vacuolated, oil red, Sudan III, PAS and Alcian blue negative. They displayed the Ia-like antigen but were negative for SIg. Ultrastructurally the vacuoles appeared empty or containing residual membrane and/or myelinoid bodies. Sometimes microvesicles were found in them. The vacuoles were mainly located in the Golgi area but they were also found in mitochondria. Cytoplasmic bodies containing microvesicles were also seen. The case is compared with those of the literature and the significance of the vacuoles is discussed.