Primary cutaneous CD4 positive small/medium T-cell lymphoma with high proliferation index and CD30-positive large lymphoid cells.

Primary cutaneous CD4 positive small/medium pleomorphic T-cell lymphoma (SMPTCL) represents a provisional subtype of primary cutaneous T-cell lymphoma with indolent clinical course. A few aggressive fatal cases with increased proliferation rate and few infiltrating CD8 positive T-cells have been reported. We describe a case of SMPTCL with an increased proliferation rate, admixed CD30-positive large lymphoid cells, and few infiltrating CD8 positive T-cells. The lymphoma cells were positive for CD3, CD4, CD2 and CD5, and negative for CD8. A subset of the lymphoma cells was positive for follicular helper T-cell markers bcl-6 and PD-1. There were approximately 20% CD30-positive large lymphoid cells, and Ki-67 showed a moderately high proliferation rate (~40%), mostly in the large lymphoid cells. CD8 infiltrating T-cells were few (<5%). The patient had an indolent disease with complete response to radiation therapy. To the best of our knowledge, this is the first reported case of SMPTCL with an increased proliferation rate and large CD30+ cells that followed an indolent clinical course.