Excellent treatment outcomes from low dose radiation therapy for primary cutaneous CD4+ small/medium T-Cell lymphoproliferative disorder.

ABSTRACT

BACKGROUND AND PURPOSE: Primary cutaneous CD4 + small/medium T-cell lymphoproliferative disorder (PCSMLPD) is a benign behaving condition, typically manifesting as solitary head or neck papules, frequently creating cosmetic concerns. Optimal management of this rare disease is unclear. Herein, patterns of care and treatment outcomes are described, with particular focus on low-dose RT. MATERIALS AND METHODS: Eligibility required biopsy-proven PCSMLPD on central review, diagnosed between 2007-2022. Patterns of care, treatment responses and relapse patterns were assessed. Freedom-from-progression (FFP) was compared between RT and surgery. RESULTS: 41 patients were eligible. First-line treatments were RT, 19 (46.3 %); surgery, 17 (41.5 %) (3 received adjuvant RT); watchful waiting, 5 (12.2 %). Median follow-up was 37.7 months. Overall, 24 patients received RT (19 definitive first-line, 3 adjuvant, 2 second-line). 10 (42 %) received 4 Gy in 2 fractions (with no acute toxicities); 14 (58 %) received 20-40 Gy. Complete response rate was 100 %. No post-RT relapses observed. After first-line surgery alone (n = 14, 3 with positive margins), 4 (28.5 %) experienced relapse (2 local, 2 distant). Watchful-waiting (n = 5) led to partial resolution post-biopsy in 4 patients; no complete resolution seen. 3-year FFP for RT alone was 100 % vs 61 % for surgery alone (p = 0.12). CONCLUSION: RT is a successful, non-invasive option for PCSMLPD 100 % achieved complete response, with no relapses, and FFP appearing numerically superior to surgery in this cohort. In this first series of low-dose RT for PCSMLPD, 4 Gy in 2 fractions appears an excellent treatment option, offering durable disease control, no acute toxicities and convenient treatment time of only 2 days.