A retrospective analysis of six patients has detailed the clinicopathological features of an extremely rare cancer: follicular dendritic cell sarcoma (FDCS) arising in the setting of Castleman disease, a lymphoproliferative disorder. The study, published open access in Diagnostic Pathology, reports that five of the six patients developed paraneoplastic pemphigus, an autoimmune blistering disease, and that clinical outcomes in the cohort were poor, with four deaths within five years.
The researchers retrospectively analyzed six cases of FDCS arising in the context of Castleman disease, evaluating clinical presentations, histopathological characteristics, and immunophenotypic profiles. The cohort comprised three male and three female patients aged 31 to 79 years. All tumors originated within lymph nodes, with two located in the mediastinum, two in the retroperitoneum, one in the axilla, and one in the pelvic cavity.
Under the microscope, the tumors showed a characteristic fascicular, whorled, or diffuse proliferation of spindle to oval cells forming nodular structures within markedly enlarged lymph nodes. Adjacent to the sarcomatous lesions, the investigators identified residual features of Castleman disease, including atrophic lymphoid follicles and hyalinized vascular proliferation. One case demonstrated extensive plasma cell infiltration in the interfollicular regions.
Immunohistochemical staining supported the diagnosis. The neoplastic cells showed variable expression of the follicular dendritic cell markers CD21, CD23, and CD35. Epidermal growth factor receptor (EGFR) was strongly positive in all five cases tested.
Five of the cases were classified as hyaline-vascular type Castleman disease with concurrent FDCS. One of these patients recurred as FDCS 31 months after surgery. The remaining case was initially diagnosed as multicentric plasma cell type Castleman disease complicated by FDCS, and the plasma cell type disease recurred seven months postoperatively. These recurrence patterns underline that the underlying lymphoproliferative disease can re-emerge even after resection of the sarcoma.
Paraneoplastic pemphigus was observed in five of the six cases. The near-universal occurrence in this small series reinforces that link.
Follow-up data painted a sobering picture. Four of the six patients died within five years, one was lost to follow-up, and one remained alive without disease. The authors conclude that, in their cohort, FDCS arising from Castleman disease was frequently associated with paraneoplastic pemphigus and demonstrated poor clinical outcomes, suggesting this subset represents a high-risk population.
The investigators caution that these observations are limited by the small sample size and require external validation. Even so, they argue that enhancing pathologists’ awareness of this distinctive association remains an essential step toward earlier diagnosis and optimized patient care, since recognizing residual Castleman disease features next to a spindle cell tumor, and confirming follicular dendritic cell differentiation immunohistochemically, can secure the diagnosis in this rare and aggressive entity.
Subject of Research: Clinicopathological features and outcomes of follicular dendritic cell sarcoma arising in association with Castleman disease
Article Title: Follicular dendritic cell sarcoma in association with Castleman disease complicated by paraneoplastic pemphigus: a retrospective analysis of six cases
Article References: Wu, H., Zhang, Z., Chen, G., Yang, M., Bian, L., & Li, Z. (2026). Follicular dendritic cell sarcoma in association with Castleman disease complicated by paraneoplastic pemphigus: a retrospective analysis of six cases. Diagnostic Pathology. https://doi.org/10.1186/s13000-026-01854-z
Image Credits: AI Generated
DOI: 10.1186/s13000-026-01854-z
Keywords: follicular dendritic cell sarcoma, Castleman disease, paraneoplastic pemphigus, retrospective study, immunohistochemistry, PD-L1, EGFR, hyaline-vascular Castleman disease, lymph node tumor, recurrence, pathology, rare cancer
News Source: Nathaniel Bowman. (October 29, 2026). Rare Sarcoma Arising From Castleman Disease Tied to Pemphigus and Poor Survival. Scienmag.
