Clinicopathological Characteristics and Clinical Course of CD8 Expressing Primary Cutaneous Peripheral T-Cell Lymphomas (CTCL) - Retrospective Case Study

CD8-positive primary cutaneous T cell lymphomas (CTCL) are rare disorders and mainly include primary cutaneous CD8-positive aggressive epidermotropic cytotoxic T-cell lymphoma (AECTL) and CD8+ variant mycosis fungoides (MF). In contrast to primary cutaneous CD8+ AECTL, which frequently exhibits strikingly aggressive and unfavorable clinical behavior, CD8+ MF shows debatable clinical course, from an indolent to aggressive behavior. As previously reported, the indolent subtype CD8+ MF occur more frequently in pediatric group, while both clinical subtypes have been observed in adults. Albeit single case studies or small case series have been reported in the literature, it still lacks a large scale of study to enlighten the clinicopathological aspects of CD8+ primary CTCLs, in order to develop the appropriate therapeutic strategies. This study aims to retrospectively review these two entities to demonstrate their clinicopathologic characteristics and to correlate them with the clinical outcome.

The hematopathology files from H. Lee Moffitt Cancer Center & Research Institute (PATHNET) and Tianjian Cancer Research Institute were retrieved. The patients with a primary diagnosis of CD8 expressing primary CTCLs, diagnosed and treated between January 2004 and June 2011, were included. Cutaneous involvement by systemic peripheral T-cell lymphoma, primary cutanous gamma delta T-cell lymphoma, and subcutaneous panniculitis-like T-cell lymphoma were excluded. The corresponding patient demographics, laboratory datas, therapeutic strategies and the clinical outcomes were reviewed. All available histology slides, along with all of the ancillary study results were reviewed and correlated with the clinical outcome.

Total of 10 cases were included based on the confirmed histomorphological diagnosis. Cases were divided into two groups: 1) CD8+ MF (n=5) and 2) CD8+ non-MF (n=5) including 2 cases with definitive diagnosis of AECTL and 3 cases diagnosed as CD8-positive primary cutaneous T cell lymphoma, not further classifiable. Clinicopathological characteristics including patients' demographic data, diagnosis, site of involvement, treatment, duration of follow up and clinical outcomes are summarized in table 1. The overall survival time for CD8+CTCLs, non-MF type (excluding 1 patient with lost follow up) varied from 5 to 90 months (averaging 20.5 months) while it was shorter in CD8+ MF, 12.6 months (5 to 23 months). Of note, 1 patient with AECTL expired shortly after diagnosis, within 3 months, however; the other one received allogeneic hematopoietic stem cell transplant (allo-HSCT) and has been alive up to date.

CD8-positive CTCLs remain a diagnostic challenge. CD8+ MF in adults exhibit dual growth patterns: localized or systemically disseminated disease. The latter could have a very short median overall survival regardless of the aggressive therapies. Allo-HSCT might be beneficial to those with AECTL. Larger series of CD8+ MF should be investigated for molecular gene profiling in order to establish genetic, molecular and phenotypic parameters not only to separate the indolent form from the aggressive subtype, but also to distinguish it from primary cutaneous CD8-positive AECTL.

No relevant conflicts of interest to declare.