Background Neoplasms of histiocytic and dendritic cell origin, including follicular dendritic cell sarcoma (FDCS), histiocytic sarcoma (HS) and interdigitating dendritic cell sarcoma (IDCS), are extremely rare, and data on their natural history and treatment outcomes are sparse. We evaluated the impact of surgery, radiation and systemic therapies on overall survival (OS). Methods We conducted a retrospective chart review of patients with FDCS, IDCS and HS treated at Memorial Sloan Kettering Cancer Center between 1995 and 2014. Results We identified 31, 15 and 7 patients with FDCS, HS and IDCS, respectively. Median age was 48.7, 42.3 and 58.8 years for FDCS, HS and IDCS, respectively. Only a slight disparity in gender distribution existed for FDCS and HS; however, IDCS predominantly affected males (6:1). The most common sites of presentation were abdomen and pelvis (42%), extremities (33%) and head and neck (57%) for FDCS, HS and IDCS, respectively. At diagnosis, 74%, 40% and 86% of patients presented with localised disease in FDCS, HS and IDCS, respectively. Patients with localised disease had significantly improved OS than those with metastatic disease in FDCS (P = 0.04) and IDCS (P = 0.014) but not in HS (P = 0.95). In FDCS and HS, adjuvant or neo-adjuvant therapy was not associated with improved OS compared with observation. In IDCS, surgery alone provided a 5-year overall survival rate of 71%. Conclusions Adjuvant or neo-adjuvant treatment in FDCS and HS did not affect OS. Patients with IDCS had an excellent outcome with surgery. In the metastatic setting, chemotherapy and small molecule inhibitors may provide benefit.

Two important factors stood out as representing an atypical presentation. First, this patient lacked any of the high-risk features of myelodysplastic syndrome that typically portend transformation. In addition, his progression to acute leukemia in 28 days from the time of diagnosis was far more rapid than the 274-day median previously described in the literature. We theorize that the presence of Sweet syndrome may have served as a predisposing factor to transformation. This finding may offer benefit to physicians to potentially better predict this outcome and pursue more aggressive treatment measures earlier in the course of the disease in such a setting.

Clinically significant RVT in patients with glomerulopathy appears to be a rather rare entity, occurring predominantly in patients with severe nephrotic syndrome due to idiopathic membranous nephropathy and membranous nephropathy secondary to autoimmune disease.