Background In the current version of the WHO classification of lymphoid tumors the term ‘grey zone lymphoma’ (GZL) was introduced for the first time. The cases of GZL with characteristics of Hodgkin lymphoma (HL) and Non-Hodgkin lymphoma (NHL) are poorly characterized in children and adolescents and need further improvement of diagnostic and treatment approaches. Patients and methods We evaluated patient’s characteristics, treatment and outcome of young GZL patients reported to the German Pediatric Hodgkin lymphoma study center and/or to the NHL-Berlin-Frankfurt-Muenster study center. Results Between 2003 and 2015, 27 children and adolescents with GZL, comprised of 22 boys and 5 girls, with a median age of 15 years, were identified. The GZL was identified at the time of initial diagnosis in 19 patients, in six patients the diagnosis was established at the time of relapse by comparing initial and relapse samples, and in two patients by a reference pathology panel which reviewed primary mediastinal B-cell lymphoma (PMLBL) cases. GZL between classical Hodgkin lymphoma (cHL) and diffuse large B-cell lymphoma (DLBCL) was diagnosed in eleven patients, GZL between cHL and PMLBL in three cases, GZL of lymphocyte predominant Hodgkin (LPHL) and T-cell rich B-cell lymphoma (TCBCL) in eleven and in two cases grey zone between LPHL and DLBCL. Fifteen patients received frontline treatment according to protocols for HL, ten patients had treatment for mature B-NHL and two had DA-R-EPOCH. Seventeen of the 27 patients relapsed. Among them, nine patients with cHL/DLBCL - four after HL treatment, four after B-NHL treatment and one after DA-R-EPOCH; both patients with cHL/PMLBL - one after HL and one after B-NHL treatment; and six with LPHL/TCRBCL - five after HL and one after B-NHL treatment. Five of the eleven patients with GZL between LPHL and TCRBCL stayed in remission after frontline treatment, compared to only three of fourteen patients with GZL between cHL and DLBCL or PMLBL. Both patients with GZL between LPHL and DLBCL stayed in remission after frontline treatment. Conclusion The diagnosis of GZL requires expert reference pathology and centralized review of staging and response evaluation. Since the relapse incidence of GZL is higher than in each of both “pure” entities HL and NHL, implementation of optimized treatment strategies for GZL is urgently needed. Therefore, global cooperative initiatives have to be undertaken, since GZL is a rare entity.
This abstract has been presented as Abstract Talk in “Grey Zone Lymphoma”