ASSESSMENT OF PERIPHERAL BLOOD TUMOUR BURDEN IN MYCOSIS FUNGOIDES AND SÉZARY SYNDROME

Background: Peripheral blood involvement is recognised as an adverse prognostic factor in Mycosis Fungoides (MF) & Sézary Syndrome (SS) which is reflected in the revised staging for MF/SS using blood (B) classification. Various methods exist to assess B classification. Objective: To assess peripheral blood involvement in MF/SS using T-cell receptor (TCR) analysis, lactate dehydrogenase levels and flow cytometric immunophenotyping. Methods: 57 consecutive patients with MF/SS assessed at our Cutaneous Lymphoma Centre, University Hospital Birmingham, UK between 2011 and 2014 were identified: 30 with early stage (I-IIA) and 27 with advanced disease (IIB-IV). Results: In early stage disease, 2/30 (7%) had identical TCR clones in skin and blood compared to 14/27 (52%) in advanced disease (p<0.001). Abnormal immunophenotyping was found in 7/27 patients (26%) with advanced disease (p=0.003) which included 6/14 (43%) erythrodermic patients but none in early stage disease. Elevated LDH was the most frequent abnormality occurring in 60% including 39% with early stage disease. Conclusion: This represents the first study of all stages of MF/SS analysed for peripheral blood involvement. Abnormal immunephenotying is unusual in early or tumour stage disease. TCR gene analysis provides a sensitive detection rate of low level blood involvement in early MF but lacks specificity hence improved sequencing techniques is required such as next generation sequencing. We suggest that standardised TCR gene analysis can be used as a screening tool in all stage MF/SS patients and those with identical clonality or advanced disease patients can be further tested with immunophenotyping