Clinicopathological and molecular study of primary cutaneous CD4+ small/medium-sized pleomorphic T-cell lymphoma

Background Primary cutaneous CD4+ small‐/medium‐sized pleomorphic T‐cell lymphoma (CD4+ PCSM‐TCL) is a rare lymphoproliferative disorder with a favorable prognosis. Distinguishing it from other cutaneous lymphomas is often a challenge. Methods We retrospectively collected CD4+PCSM‐TCL cases from two centers (MD Anderson Cancer Center, USA and University of Milan, Italy) and evaluated their clinicopathological features. Array‐comparative genomic hybridization (aCGH) analysis was performed on 11 cases. Results A total of 62 patients were identified. Single lesions were the most common clinical presentations (79%). Five patients (8%) showed multiple MF‐like plaques. All patients' disease had an indolent course. The infiltrate was nodular and diffuse, multinodular or superficial but in all cases, it was characterized by small/medium pleomorphic CD4+/CD279(PD1+) lymphocytes grouped in clusters and ‘pseudorosettes’ around B‐cells. aCGH analysis showed no significant genomic abnormalities. Single lesions were mainly treated with surgical excision (91%) and/or radiotherapy (95%) with low rate of relapse (12%). For multiple lesions, topical steroids, nitrogen mustard and phototherapy were mainly used but the rate of relapse was high (69%). Conclusions CD4+PCSM‐TCL is characterized by heterogeneous clinical presentations. The arrangement of atypical cells in clusters or pseudorosettes is a useful criterion for diagnosis. The absence of significant genomic alterations is in agreement with its indolent behavior.