Neoplasms of reticular dendritic origin are extremely rare and include the follicular dendritic cell sarcoma (FDCS) and the interdigitating reticulum (or dendritic) cell sarcoma (IDCS). In this article, we review the literature pertaining to the two diseases and describe clinical observations and salient pathologic features, including information provided by authors of FDCS and IDDCS reports. We performed a computerized database search for published articles regarding FDCS and IDDCS. The articles were evaluated critically by the authors. Simple descriptive statistics were used to analyze the data. There are 51 cases of FDCS and 21 cases of IDDCS that are well documented in the literature. The pathologic diagnosis of FDCS and IDDCS is often challenging and requires morphologic, immunophenotypic, cytochemical, and electron-microscopic analysis. Patients with FDCS usually present with cervical or axillary lymphadenopathy, but extranodal disease has been described. In at least some patients, preexisting Castleman's disease has been recognized. Resected localized disease may be prevented from recurrence by consolidative radiotherapy. Chemotherapy regimens have shown nondurable antitumor activity in FDCS. Patients with IDDCS usually present with lymphadenopathy. The clinical course of IDDCS has been variable, but it seems to be more aggressive than that of FDCS. Variable degrees of remission may be achieved with chemotherapy. FDCS and IDDCS are rare neoplasms that may pose difficulty in pathologic diagnosis. IDDCS seems to display a more aggressive behavior than FDCS. Patients with IDDCS and FDCS can eventually die of disease progression. The role of chemotherapy and radiotherapy is not clearly defined.