[Diagnosis and classification of cutaneous pseudolymphoma. Historical review and perspectives]

Cutaneous pseudolymphomas are benign hyperplastic lymphoproliferative reactions that simulate cutaneous malignant lymphomas clinically and/or histologically. The differentiation between cutaneous pseudolymphomas and primary cutaneous lymphomas is often very difficult, but is important because it may have therapeutic consequences. The term pseudolymphoma does not refer to a specific disease, but to a heterogeneous group of pseudo-B-cell lymphomas and pseudo-T-cell lymphomas. In this review the definitions and classification of cutaneous pseudo-B-cell lymphomas and pseudo-T-cell lymphomas will be discussed, with emphasis on the changing concepts that have resulted from the introduction of new diagnostic methods. The various differential diagnostic criteria that have resulted from these concepts will be presented.