Cutaneous lymphomas: a proposal for a unified approach to classification using the R.E.A.L./WHO Classification

Area of Science:

• Hematology
• Oncology
• Dermatopathology

Background:

• The classification of cutaneous lymphomas remains controversial.
• The European Organisation for Research and Treatment of Cancer (EORTC) proposed a unique system for cutaneous lymphomas.
• Conventional classification schemes have been deemed unsuitable for cutaneous lymphomas.

Purpose of the Study:

• To review the suitability of the R.E.A.L. Classification for cutaneous lymphomas.
• To compare the R.E.A.L. Classification with the proposed EORTC system.
• To advocate for a unified classification system for all lymphomas.

Main Methods:

• Review of the R.E.A.L. Classification principles and their adoption by the World Health Organization (WHO).
• Comparison of the R.E.A.L. Classification with the EORTC proposed system for cutaneous lymphomas.
• Integration of morphology, immunophenotypic and genetic features, clinical presentation, and course in disease definition.

Main Results:

• Organ-specific classification systems may obscure common disease features across different anatomic sites.
• The EORTC Classification for cutaneous lymphomas, while addressing dermatologists' needs, could lead to confusion by introducing multiple systems.
• Cutaneous lymphomas may exhibit more indolent behavior than nodal lymphomas, potentially requiring distinct therapeutic strategies.

Conclusions:

• Organ-specific classification schemes for cutaneous lymphomas are unnecessary and may hinder recognition of shared disease characteristics.
• A unified R.E.A.L./WHO Classification system should be adopted for all lymphomas, irrespective of their site of origin.
• Clinical features, including systemic spread and site of origin, are crucial for prognosticating and guiding therapy for cutaneous lymphomas.