Abstract: 【Abstract】 Objective To retrospectively analyze the clinicopathological features, treatment, and prognosis of patients with primary cutaneous T-cell lymphoma. Methods This retrospective cohort study included 80 patients aged ≥ 18 years who were diagnosed with primary cutaneous T-cell lymphoma in the Department of Dermatology, Peking University Third Hospital between January 2012 and June 2024. Demographic characteristics, laboratory findings, pathological data, treatment regimens, and prognosis up to December 31, 2024 were collected and analyzed. Patients were classified as mycosis fungoides or other subtypes of primary cutaneous T-cell lymphoma, and differences in clinicopathological characteristics and prognosis among subgroups were evaluated. Measurement data were analyzed using the t test or Wilcoxon rank-sum test, and categorical data were compared using the chi-square test or Fisher′s exact test. Cox regression models were used to evaluate the effect of disease subtypes or stages on prognosis. Survival curves were plotted using the Kaplan-Meier method, and compared between groups using the log-rank test. Results Among the 80 patients with primary cutaneous T-cell lymphoma, 48 （60.00%） were diagnosed with mycosis fungoides, 8 （10.00%） with primary cutaneous anaplastic large cell lymphoma, 8 （10.00%） with primary cutaneous peripheral T-cell lymphoma, not otherwise specified, 6 （7.50%） with lymphomatoid papulosis, 6 （7.50%） with primary cutaneous extranodal NK/T-cell lymphoma, and 4 （5.00%） with subcutaneous panniculitis-like T-cell lymphoma. The patients with mycosis fungoides included 35 （72.92%） males and 13 （27.08%） females, and were aged 50.50 ± 15.13 years; 38 （79.17%） were alive and 10 （20.83%） had died. Among patients with other non-mycosis fungoides subtypes, 19 （59.38%） were males, 13 （40.63%） were females, and 8 （25.00%） had died. Unfavorable prognostic factors in the mycosis fungoides group included advanced age, male gender, history of diabetes mellitus, and concomitant infections （all P < 0.05）; laboratory parameters associated with poor prognosis included lymphopenia, elevated lactate dehydrogenase levels, and increased β2-microglobulin levels （all P < 0.05）; pathologically, a high Ki-67 proliferation index was significantly associated with poor prognosis （P < 0.05）; in terms of treatment, combination chemotherapy was associated with poor outcomes （P < 0.05）. Prognostic analysis showed that patients with stage Ⅲ mycosis fungoides （HR = 4.60, 95% CI: 1.96 - 10.79） and stage Ⅳ mycosis fungoides （HR = 31.28, 95% CI: 4.35 - 86.26） had significantly higher mortality rates compared with those with stage ⅠA mycosis fungoides （HR = 1.00）; in addition, patients with primary cutaneous extranodal NK/T-cell lymphoma （HR = 18.50, 95% CI: 1.90 - 179.90） and primary cutaneous peripheral T-cell lymphoma, not otherwise specified （HR = 8.76, 95% CI: 1.11 - 68.94） had significantly higher mortality rates than those with mycosis fungoides （HR = 1.00） （all P < 0.05）. Conclusions Early diagnosis is crucial for primary cutaneous T-cell lymphoma. Multiple factors, such as lymphopenia, elevated lactate dehydrogenase levels, and increased β2-microglobulin levels, may be associated with poor prognosis. Patients with advanced-stage mycosis fungoides, primary cutaneous extranodal NK/T-cell lymphoma, and primary cutaneous peripheral T-cell lymphoma, not otherwise specified, seem to have higher mortality rates.

Key words: Lymphoma, T-cell, cutaneous, Kaplan-Meier estimate, Prognosis, Root cause analysis