Interdigitating dendritic cell sarcoma: Clinicopathologic study of 8 cases with review of the literature.

To investigate the clinicopathologic features and differential diagnoses of interdigitating dendritic cell sarcoma (IDCS), the clinical, morphological and immunohistochemical features of eight cases of IDCS were collected and analyzed. Three patients were males and five were females, the mean age and the median age were 56.5 years and 57 years respectively. Clinically, the majority of cases involved lymph nodes. Microscopically, neoplastic cells were spindle or ovoid, forming fascicles or whorls. Every case had active mitosis figures. Immunohistochemically, these neoplastic cells were consistently positive for S100, but negative for CD21 and specific B-cell and T-cell associated antigens. Follow-up results were available in 7 cases, of which 5 cases of localized lesions survived, 2 cases died of organ involvement. Interdigitating dendritic cell sarcoma is an extremely rare neoplasm, with inferior prognosis and without standard treatment regimen. IDCS has similar but unique clinicopathologic features and the differential diagnoses include other histiocytic and dendritic cell neoplasms and malignant melanoma.