Atypical cutaneous lymphocytic infiltrate and a role for quantitative immunohistochemistry and gene rearrangement studies

Aim To help clarify the significance of the T-cell receptor (TCR) gene rear rangement and its relationship to the immunophenotyping of histologically a typical cutaneous T-cell lymphoid infiltrates (ACLIs). Materials and methods One hundred and twenty-four patients presented with l esions clinically suspicious for cutaneous T-cell lymphoma (CTCL). The aver age age was 55.8 years with a mean follow-up duration of 26.2 months. Cases were classified as malignant (64 cases), inflammatory dermatosis (28 cases ), and indeterminate (32 cases), based on follow-up data and histopathology . Quantitative immunophenotyping with computer-assisted imaging was perform ed using immunohistochemical stains of anti-CDS, CD4, CD5, CD7, CD8, CD20, CD30, CD56, CD68, Bcl-2, p53, and proliferating cell nuclear antigen (PCNA) . Results Abnormal immunophenotypic expression in 87.5% of the malignant case s, including CD4 or CD8 predominance (67%), deletion of pan-T-cell antigens (16.1%), and activation of antigen/oncogene expression (47%), was observed . In addition, 36 clinically malignant cases displayed rearranged bands by polymerase chain reaction (PCR) with TCR beta and gamma. Two benign cases d isplayed abnormal immunophenotype and two others showed rearranged bands. A ll of these patients responded to topical steroid therapy with complete res olution. Nineteen indeterminate cases displayed either rearranged bands or immunophenotypic abnormalities, 15 of which were reclassified as malignant. All but three patients improved after CTCL treatment. Conclusion Quantitative immunophenotyping and gene rearrangement analysis c an provide detailed information for classifying ACLIs with 91% diagnostic s ensitivity and 87% specificity.