Primary Cutaneous Gamma-Delta T-Cell Lymphoma (PCGDTCL) Descriptors and Clinicopathologic Determinants of Survival: Analysis of a Pooled Database

Abstract

Introduction Primary Cutaneous Gamma-Delta T-cell Lymphoma (PCGDTL) is a rare clinical entity that represents <1% of all cutaneous lymphomas. It is characterized by clonal proliferation of mature, activated T-cells expressing the T-cell receptor (TCR) γ/δ and cytotoxic molecules. PCGDTL is often resistant to conventional chemotherapy and is usually associated with poor prognosis. We have conducted this pooled database analysis to delineate key disease characteristics and clinicopathologic determinants of survival in this rare cutaneous T-cell lymphoma. Methods To study the demographic characteristics, molecular and immunohistochemical signatures, therapeutic interventions, survival, and prognostic factors, we compiled a pooled database of 140 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 (OS). Results A total of 140 patients with confirmed PCGDTCL were identified. The median age was 54 years with peak incidence between ages 52 and 65 years. There was no sex preponderance. The median duration of symptoms prior to diagnosis was 9 months. Eighty percent of patients presented with >4 lesions with an average size of 3.4cm. The disease involved mostly the lower extremities followed by the upper extremities, trunk, and lastly the face. Almost all the lesions involved the dermis with 48% involving the epidermis. Twenty-four percent of the lesions presented with ulceration and 30% had fat necrosis. Patients presented with constitutional symptoms in 28%, splenomegaly 6%, lymphadenopathy 16%, and hemophagocytic syndrome (HPS) 13%. Compared to no treatment, combination chemotherapy and stem cell transplant (SCT) were statistically superior with median OS months of 2, 16, and not reached respectively (p<0.0001). Age inversely correlated with survival while time from symptoms to diagnosis has a positive correlation. CD30+ imparted a survival advantage while HPS was detrimental to OS, both at borderline significance. Visceral involvement was also associated with a worse median OS (9.5 vs 18 months). OS was not impacted by sex, size of the lesions, or subcutaneous involvement. While solitary disease and absence of constitutional symptoms and bone marrow involvement seemed to have better OS, they did not reach statistical significance. Conclusions This study presents an updated clinicopathologic data from a pooled cohort of patients with PCGDTCL. It details the features of this rare disease and identifies the clinical, immunohistochemical, and treatment modalities that are major determinants of OS.