Interdigitating Dendritic Cell Sarcoma and Indeterminate Dendritic Cell Tumor: Patient Characteristics, Prognostic Factors, and Survival Outcomes for Rare Dendritic Cell Neoplasms

• Published in: Blood 2023-11, Vol.142 (Supplement 1), p.5346-5346
• Main Authors: Fugere, Tyler, Fugere, Brad, Amisha, Fnu, Chen, Jim Zhongning, Mukherjee, Akash, Gaddam, Mamatha, Veeraputhiran, Muthu, Gentille Sanchez, Cesar Giancarlo
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2023-187700

Background Dendritic cells are nonlymphoid, nonphagocytic, antigen-presenting cells present in lymphoid and nonlymphoid tissue. There are 4 types of dendritic cells: follicular, interdigitating, Langerhans, and fibroblastic cells. The WHO 2022 classification system groups dendritic cell and histiocytic neoplasms into 3 categories: plasmacytoid dendritic cell neoplasms, Langerhans cell and other dendritic cell neoplasms, and histiocytic neoplasms. The 2nd category is subdivided into “Langerhans cells neoplasms” and “other dendritic cell neoplasms”, which contains indeterminate dendritic cell tumor (IDCT) and interdigitating dendritic cell sarcoma (IDCS). The 2022 classification eliminated follicular dendritic cell sarcoma (FDCS) as it is no longer thought to be of hematopoietic origin. A prior Surveillance, Epidemiology, and End Results (SEER) review published in 2013 by Perkins and Shinohara grouped FDCS and IDCS and included 20 cases of IDCS diagnosed between 2001 and 2008. To our knowledge, this is the first update of epidemiologic and survival data for non-Langerhans cell and non-plasmacytoid dendritic cell neoplasms since the WHO reclassification. Methods We used the SEER 22 database, which collects data from cancer registries covering approximately 47.9% of the U.S. population. We selected all patients with cancers falling in the “other dendritic cell neoplasms” category according to the WHO 2022 classification from 2000-2020 using International Classification of Diseases for Oncology edition 3 (ICD-O-3) code of 9757/3, which codes for IDCS but also includes IDCT. The Kaplan-Meier method was used to display the survival curves. The Cox proportional hazards model was used to determine p values. Results A total of 72 cases of IDCS/IDCT were identified. Median follow up was 19 months and median OS for the entire cohort was 24 months (95% CI 10-92 months). Of these patients, 61.1% (n=44) were White, 16.7% (n=12) were Hispanic, 13.8% (n=10) were Black, 5.6% (n=4) were Asian or Pacific Islander, and 2 patients were of unknown race. IDCS/IDCT was more common in males than females with a ratio of 1.77. The most common primary sites of involvement were connective tissue in 40.2% (n=29), head and neck in 16.7% (n=12), lymph nodes in 11.1% (n=8), and bone marrow in 8.3% (n=6). Patients with bone marrow involvement had a trend towards worse OS (median OS of 5 months). IDCS/IDCT is more common in adults but does occur in children and adolescents. Only 6 cases were