Unicentric castleman disease located in the left popliteal fossa: a case report

BACKGROUND: Castleman disease (CD) is a lymphoproliferative disease of unknown etiology, it can affect any lymph nodes of the body but rarely affects the popliteal fossa. CASE PRESENTATION: We present a 67-year-old woman with touching solitary painless mass in the left popliteal fossa for one week. Imaging showed multiple soft-tissue masses of different sizes in the left popliteal muscle space, the T1 weighted image showed hypointense to isointense, the fat-suppressed T2 weighted images showed subtle hypersignal intermingled with linear of hypointense,and displayed homogeneous contrast enhancement after administration of gadolinium. Complete surgical resection was performed. Pathologically demonstrated plasma cell type CD. CONCLUSION: We described a rare case plasma cell type of UCD located in the popliteal fossa which might help to enrich the clinical spectrum of this rare site and unique subtype of UCD. This case illustrates that CD should be considered in the differential diagnosis of every hypervascularity soft tissue tumor in any anatomic location, especially when they occur in the region of lymph node distribution.