The applicability and prognostic value of the new TNM classification system for primary cutaneous lymphomas other than mycosis fungoides and Sézary syndrome: results on a large cohort of primary cutaneous B-cell lymphomas and comparison with the system used by the Dutch Cutaneous Lymphoma Group.

BACKGROUND

Recently, a consensus proposal was published for a TNM classification system for all primary cutaneous lymphomas other than mycosis fungoides and Sézary syndrome, meant to document extent of disease in a consistent manner. The applicability and the prognostic significance of this system have not been investigated thus far.

OBJECTIVES

To test the applicability and prognostic relevance of the proposed TNM classification system on a cohort of primary cutaneous B-cell lymphomas (CBCL).

METHODS

The study group included 71 primary cutaneous marginal zone lymphomas (PCMZL), 171 primary cutaneous follicle centre lymphomas (PCFCL) and 58 primary cutaneous diffuse large B-cell lymphomas, leg type (PCLBCL, LT). As only patients with primary cutaneous lymphoma were included (T1-3, N0M0), only the T-rating was scored. The results were compared with the scoring as applied by the Dutch Cutaneous Lymphoma Group.

RESULTS

The system was easily applicable to all cases. In PCMZL and PCFCL no correlation was found between T-score and survival (5-year disease-specific survival: T1, 100% and 98%; T2, 94% and 93%; T3, 100% and 88%, respectively). In PCLBCL, LT there was a clear, although statistically not significant, association between increasing T-score and reduced survival (5-year disease-specific survival: T1, 75%; T2, 49%; T3, 0%; P = 0.077). Comparing the TNM system with the Dutch Cutaneous Lymphoma Group system, there was a discrepancy in the classification of 20 cases.

CONCLUSIONS

The new TNM system is a useful tool to document disease extent in patients with CBCL and provides prognostic information in the group of patients with PCLBCL, LT.