T-cell signet-ring cell lymphoma. A histologic, ultrastructural, and immunohistochemical study of two cases.

The histologic, ultrastructural, and immunologic characteristics of two signet-ring cell lymphomas of T-cell derivation are presented. Histologically, both lymphomas were diffuse large cell lymphomas with many neoplastic cells containing cytoplasmic vacuoles imparting a signet-ring configuration. Ultrastructural examination revealed the vacuoles to consist of electron-lucent spaces containing variable numbers of microspherules. Immunohistochemical studies showed that both lymphomas expressed T-cell phenotypes with no reactivity with antibodies to B-cell antigens. In contrast to previous reports which have shown signet-ring cell lymphomas to be invariably B-cell in derivation and usually follicular center cell type, this study demonstrates that these lymphomas may also be of T-cell origin.