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.