CD4+ CD56+ cutaneous neoplasms: A distinct hematological entity?

We report seven cases of particular cutaneous tumors selected from the regi ster of the French Study Group on Cutaneous Lymphomas. The patients (three men, four women) were aged 37-86 years. They initially presented with cutan eous nodules or papules. Three cases presented with regional lymph nodes. S tagings were negative, except for one patient with bone marrow involvement. Histological features were relevant with pleomorphic medium T-cell lymphom a, but these cells exhibited a distinguishing phenotype. They were positive for CD4, CD56, and also CD45, CD43, and HLA-DR. All other T-cell and B-cel l markers were negative. The myelomonocytic markers (CD13, CD14, CD15, CD33 , CD117, myeloperoxidase, and lysozyme) were negative excepted CD68, which was clearly positive in four cases and weakly in two cases. Others natural killer cell markers (CD16, CD57, TiAl, granzyme B), TdT, and CD34 were nega tive. Polymerase chain reaction studies did not detect any B or T clonal re arrangement. The cytogenetic studies, performed in five cases, showed a del (5q) in two cases. All patients were treated successfully by polychemothera py, but relapsed quickly in the skin, between 4 and 28 months. Five patient s developed bone marrow involvement, with leukemia in three cases, and they died in 5-27 months. One patient died at 17 months with skin progression. The seventh patient is alive at 33 months, with cutaneous progression. The origin of these cells is unclear. Despite expression of CD4 or CD56, we fai led to demonstrate a T-cell, natural killer cell origin. However, CD4 and C D56 are not specific for T or natural killer lineages. Although these two m arkers are also known to be expressed by monocytic cells, classic myeloid a ntigens were negative. These seven cases, together with other rare similar cases already reported, seem to represent a distinct entity likely develope d from hematological precursor cells.