[Clinicopathological characteristics of indeterminate dendritic cell tumor of four cases]

Objective: To investigate the clinicopathologic features, diagnosis, differential diagnosis and molecular pathological characteristics of indeterminate dendritic cell tumor (IDCT). Methods: Four cases of IDCT were collected at Peking Union Medical College Hospital (3 cases) and Fujian Provincial Hospital (1 case). The 4 cases were analyzed, with focus on morphology, immunohistochemistry and BRAF V600E detection. Related literature was reviewed to reveal the characteristics of this tumor. Results: There were 2 males and 2 females aged 30-52 years (mean=40 years). Histopathological characteristics of the tumor cells were round, polygonal. The nuclei were round, with rich eosinophils cytoplasm. The tumor cells arranged in diffuse, sheet, whorl, and fascicle patterns. Mitosis was variable [generally(1-3)/10 HPF] and nucleoli were obvious. Lymphocytes, plasma cells and other infiltrates could be seen in the stroma. Immunohistochemically, tumor cells were positive for S-100 (4/4), CD1a (4/4), CD68 (4/4) and cyclin D1 (3/3), while CD207/Langerin, CKpan, CD21, HMB45, ALK and actin were negative. Ki-67 index was 5%-30%. Gene detection showed BRAF V600E mutations were not present in any of the four cases. Conclusions: IDCT is a rare type of dendritic cell tumor. There are no specific morphology characteristics. The diagnosis depends on clinical, histopathological and immunophenotype. Thus, electron microscopy and molecular testing are helpful if necessary.