Clinical features, treatment options and outcomes in primary cutaneous B-cell lymphomas: a real-world, multicenter, retrospective study.

Background: Primary cutaneous B-cell lymphomas (PCBCLs) are rare cutaneous neoplasms with limited literature regarding treatment options and associated treatment outcomes. This study aimed to investigate and present real-world treatment outcomes in patients with PCBCLs.

Methods: All patients with PCBCL who were treated in five major referral centers for cutaneous lymphoma in Greece over 10 years were retrospectively included with their baseline characteristics and treatment-associated outcomes collected and analyzed.

Results: In total, 235 PCBCL patients, of whom 125 (53.2%) were females, were included. The median age at diagnosis was 60 years (IQR 47-72), and the median follow-up duration was 3 years (IQR 1.3-6.4). The most common subtype was primary cutaneous marginal zone lymphoma (PCMZL) (52.3%), followed by primary cutaneous follicle center lymphoma (PCFCL) (40.9%), and primary cutaneous large B-cell lymphoma, leg type (PCDLBCL, LT) with 16 (6.8%) cases. Complete responses (CRs) were observed in 77.3% after first-line treatment. Both radiotherapy (RT) and surgical excision (SE) achieved superior outcomes, with 88.9% and 89% achieving CR, respectively. Relapses occurred in 22.6% of initial complete responders. The median time to the next treatment (TTNT) for the PCMZL and PCFCL was 349 days. RT and topical/intralesional steroids demonstrated longer TTNT compared to SE (445 and 359 vs. 154 days). For PCMZL and PCFCL, the 1-year progression-free survival (PFS) was 84.2% (75.7-89.9) and 85% (75.1-91.2), and the 5-year PFS was 66.5% (55.2-75.5) and 58.8% (44.4-70.7), respectively.

Conclusions: PCBCLs have favorable outcomes. RT demonstrates significantly increased TTNT compared to SE, suggesting RT as the preferable option. After careful evaluation, "watch and wait" may be a reasonable option for asymptomatic patients.