UCD with MCD-like inflammatory state: surgical excision is highly effective.

Unicentric Castleman disease (UCD) is a rare lymphoproliferative disorder presenting as a single nodal mass with characteristic histopathology. Patients with UCD are typically asymptomatic with normal laboratory markers, whereas patients with multicentric Castleman disease (MCD) demonstrate multicentric lymphadenopathy and cytokine storm-induced systemic inflammatory symptoms. This retrospective analysis of 116 UCD cases identified 19 (16.4%) cases with an MCD-like inflammatory state (UCD-MIS). We compared treatments and outcomes between cases of UCD-MIS and UCD-non-MIS to evaluate the role of surgery and illuminate biological behavior of UCD-MIS. There were differences in the distribution of histopathological subtypes (plasmacytic histopathology was more frequently seen, 52.6% vs 13.4%; P < .001) between the 2 groups. However, both groups demonstrated good responses to surgical treatment, suggesting that UCD-MIS in some patients still shared common biological behavior with UCD in other patients. Sixteen (94.2%) patients with UCD-MIS underwent complete surgical excision alone, and the systemic inflammation resolved completely in all of them. This high response rate suggests surgical treatment as a potential cure for this unique subset of patients. After a median follow-up duration of 64 months (range, 2-239 months), neither lymphadenopathy nor the inflammatory state recurred. However, inflammation may progress in patients with irresectable disease, and treatment options other than surgery should be considered in these patients.