Abstract 4129: Descriptors of primary cutaneous follicular helper T-cell lymphoma (PCFHTCL): Analysis of a pooled database of a rare entity

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Abstract Introduction: Primary Cutaneous Follicular Helper T-cell Lymphoma (PCFHTCL) is a rare cutaneous T-cell lymphoma that was recently described. PCFHTCL is comprised of small to medium lymphocytes that express CD4, CD19, Bcl6, PD1, ICOS, CXCR5, and CXCL13. While it tends to have mostly an indolent course, occasionally PCFHTCL may display a more aggressive pattern. We conducted this analysis to explore the key clinicopathologic characteristics of this rare and little-known entity. Methods: In order to study the demographic characteristics, molecular and immunohistochemical signatures, therapeutic interventions, survival, and prognostic factors, we compiled a pooled database of 57 cases. Kaplan-Meier survival curves were constructed. Cox proportional-hazards model and Log-rank tests were used to assess the influence of demographic and clinicopathologic factors on overall survival and disease-free survival. Results: A total of 57 patients with confirmed PCFHTCL were identified. The median age was 57 years with a peak incidence between ages 53 and 64. There was a male predominance with an M:F ratio of 1.25. PCFHTCL commonly involved the head (54%), followed by the torso (24%) and limbs (12%). Sixteen percent of the lesions were solitary and mostly involved the head. The most common pattern was nodular/tumorous. Histologically, PCFHTCL involved mainly the dermis with occasional focal epidermotropism (27%), folliculotropism (43%), syringotropism (7%), and subcutaneous extension (14%). Extracutaneous involvement comprised lymph nodes (11%), bone marrow (4%), and the peripheral blood (2%). The median duration of symptoms prior to diagnosis was 5 months. The six-year disease-free survival is around 85%. Surgical resection alone resulted in durable remission in 40% of the cases. Recurrent disease was successfully salvaged with re-resection, radiation, and chemotherapy. While solitary lesions tended to have a better disease-free survival, it did not reach statistical significance. Conclusions: This study represents the largest cohort of this rare cutaneous T-cell entity. It describes the demographic and clinical patterns of disease presentation and provides a detailed update on the clinicopathologic features PCFHTCL. Citation Format: Philip A. Haddad, Dalia Hammoud, Kevin Gallagher. Descriptors of primary cutaneous follicular helper T-cell lymphoma (PCFHTCL): Analysis of a pooled database of a rare entity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4129.