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

To help clarify the significance of the T-cell receptor (TCR) gene rearrangement and its relationship to the immunophenotyping of histologically atypical cutaneous T-cell lymphoid infiltrates (ACLIs).

One hundred and twenty-four patients presented with lesions clinically suspicious for cutaneous T-cell lymphoma (CTCL). The average 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 performed using immunohistochemical stains of anti-CD3, CD4, CD5, CD7, CD8, CD20, CD30, CD56, CD68, Bcl-2, p53, and proliferating cell nuclear antigen (PCNA).

Abnormal immunophenotypic expression in 87.5% of the malignant cases, 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 displayed abnormal immunophenotype and two others showed rearranged bands. All of these patients responded to topical steroid therapy with complete resolution. 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.

Quantitative immunophenotyping and gene rearrangement analysis can provide detailed information for classifying ACLIs with 91% diagnostic sensitivity and 87% specificity.