B-cell lymphofollicular infiltrates in mycosis fungoides.

AIMS AND BACKGROUND The histopathological picture of mycosis fungoides can be characterized by heavy reactive infiltrates. These are rarely composed of B lymphocytes with formation of reactive follicles. METHODS AND STUDY DESIGN We collected three cases of mycosis fungoides with a reactive B-cell lymphofollicular reaction at the bottom of the epidermotropic infiltrate. RESULTS Case 1 showed flat lesions (patches) with a CD4+ neoplastic phenotype; case 2 presented infiltrated lesions (plaques) with a CD8+ immonophenotype; case 3 was characterized by nodular lesions (tumors) with a CD4+ neoplastic component. In all three cases, no clonal gene rearrangement was found with the polymerase chain reaction technique. CONCLUSIONS Among the protean clinicopathological features which mycosis fungoides can show, we underline that a B-cell lymphofollicular component can be encountered at the base of the epidermotropic infiltrate even in clinically flat ("patchy") lesions.