Evaluation of CD[7] T-cell deletion marker for diagnosis of mycosis fungoides

Clinical diagnosis of mycosis fungoides [MF] in its early stages can be difficult and requires biopsy confirmation of disease. Even with histological evaluation, early-stage MF is still difficult to distinguish from various benign inflammatory dermatoses [BID]. Recent attempts to enhance the diagnostic sensitivity and specificity have mainly focused on lymphocyte Immunophenotyping and genotyping [1, 2]. Our purposes in this study were clinical and histopathologic assessment of MF patients in addition to evaluate the diagnostic value of Immunophenotyping with special reference to CD7 deletion. The study was carried on 19 MF patients and 16 cases of BID as a control group. They were subjected to full clinical examination, routine laboratory investigations and chest x- ray. Skin biopsies were obtained from all MF cases and BID control group. The paraffin embedded skin specimens were stained with hematoxylin-eosin stain [H and E] and immunostains for CD3, CD4, CD8 and CD7. According to Smoller's [3] histological criteria, the diagnosis of MF was confirmed; showing various pathologic patterns including granulomatous MF in one case. Immunophenotyping results revealed that T-cells in all MF and BID specimens were predominantly expressed CD3+, CD4+ and negatively stained by CD8. Conversely, the mean CD7+ count as a percentage of total T-cells in MF specimens [16.8%] was significantly lower than those of BID [61.7%]. The sensitivity and specificity of CD7 deletion [expressed by <50% of T-cells] for diagnosis of MF was 89.5% and 93.75% respectively. CD4/CD8 ratios greater than 2:1 and 10:1 were noticed in 73.7% and 31.3% of MF biopsies. CD4/CD8 ratios more than 10:1 were specific for MF while ratios greater than 2:1 were also found in 15.8% of BID. We can conclude that MF may manifest a variety of histological forms. Expressions of conventional T-cell markers including CD3, CD4 and CD8- do not generally distinguish benign T-cell infiltrate from MF, however, deletion of CD7 [<50%] has demonstrated considerable usefulness in the diagnosis of MF [89.5%] and was occasionally found in BID [6.25%]