An angiosarcoma of spleen was initially suspected and a laparoscopic splenectomy was performed to confirm the diagnosis and clarify a treatment strategy. The macroscopic cut section showed an ovoid well circumscribed mass measuring 5.5 × 4.8 cm (Fig. 2A). The microscopic view showed relatively well circumscribed mass consisting of epithelioid or spindle shaped cells and infiltrated lymphoplasma cells with hemorrhage. The neoplastic spindle cells arranged in fascicled or whorling pattern with ovoid nuclei, delicate chromatin, small nucleoli and abundant eosinophilic cytoplasm (Fig. 2B–D). Immunohistochemical staining revealed focal positivity for cluster of differentiation 21 (CD21) (Fig. 2E), CD23 and positivity for Epstein-Barr virus (EBV) by in situ hybridization (Fig. 2F). These findings were consistent with inflammatory pseudotumor (IPT)-like follicular/fibroblastic dendritic cell (FDC) sarcoma.

FDC sarcoma is rare malignant tumor that can involve lymph nodes or extranodal sites. The neoplastic cells are predominantly positive for FDC markers such as cluster of CD21, CD23, CD35 and CNA.42. IPT-like FDC sarcoma cells are consistently associated with EBV, whereas conventional FDC sarcomas are negative for EBV, so EBV plays important role in the diagnosis of IPT-like FDC sarcoma. Radical surgical resection is the main therapy for IPT-like FDC sarcoma and the role of adjuvant chemotherapy is unclear. Annual surveillance is recommended, because of a certain risk of relapse after the initial therapy of IPT-like FDC sarcoma.