Cutaneous T cell lymphoma of signet ring cell type: a specific clinico-pathologic entity.

We describe a new case of signet ring cell peripheral T cell lymphoma in a 45-year-old man. This lymphoma had a very indolent course, since--without treatment--the clinical staging has shown no evidence of disease progression 11 years after initial symptoms. Immunophenotype indicated pan T antigens (Leu 4 CD3, Leu 1 CD5) and T suppressor cytotoxic antigen (IOT8 CD8) expression. Several T antigens (Leu 5b CD2, Leu 9 CD7, Leu 3a CD4) were not expressed. The proliferation index was less than 5% with Ki 67 monoclonal antibodies. The ultrastructural study showed characteristic cytoplasmic vacuoles containing microvesicles. Five cases of signet ring T cell lymphoma, which were very similar to our case, have been previously described. Their characteristics were primary cutaneous presentation, indolent course, good response to current therapies and a long survival period. The indolent course of these signet ring cell lymphomas may indicate that this type of lymphoma is a low grade malignant lymphoma and not only a morphological pattern.