P106 Mycosis fungoides with a CD56+ immunophenotype: report of 2 cases

Abstract

Introduction In patients with typical mycosis fungoides, proliferating lymphocytes show a characteristic CD3+CD4+CD8− phenotype, typical of T-helper lymphocytes. However, in some instances, T-suppressor/cytotoxic or aberrant T-cell phenotypes have been described. In contrast, the CD56+ cutaneous lymphomas reported in the literature generally do not present like MF and bear a poor prognosis. Methods We report two cases of MF with a CD56+ cytotoxic immunophenotype. Clinical features, treatment response and immunohistological findings are briefly described. Results The first patient was a 46 year old female with multiple poikilodermatous patches on the trunk and extremities as well as crusted papules on the extremities which spontaneously resolved and healed without scarring. Skin biopsies from two clinically different lesions were compatible with LyP type B (clinically crusted papule), and MF (clinically chronic, itching plaque). The lymphocytic population in both lesions had a similar immunophenotype (CD2+, CD3+, CD4−, CD7−, CD8+, CD30−, TIA+) with additional positivity for CD56 antigen and identical clonal rearrangements of the genes of TcRγ receptor detected by PCR analysis. Patient was treated with PUVA and the disease is under remission for 28 months. The second patient is a 53 year old female patient presented with erythematous patches on the buttocks and lower extremities as well as a tumorous lesion at the right buttock. Histology of the tumor was diagnostic for tumor stage MF. Neoplastic lymphocytes had a CD2+, CD3+, CD4+, CD7−, CD8−, CD30−, CD56+ immunophenotype whereas clonal rearrangement of the genes of TCRγ receptor were detected by PCR analysis. The tumor was treated with radiotherapy and the remaining disease was treated with PUVA plus interferon a-2b 3MU tiw. Our patient is under remission for 8 months. Conclusion Cases of MF with CD56+ immunophenotype are extremely rare. In contrast to blastic natural killer cell lymphoma and subcutaneous panniculitis-like T cell lymphomas where expression of CD56 is associated with a poor prognosis, in our cases the disease behaved in a manner similar to that predicted for MF with a normal immunophenotype. Recognition and proper classification of cases of mycosis fungoides with CD56+ phenotype is crucial in order to avoid unnecessary aggressive treatment for these patients.