Asymptomatic huge spleen mass

A 69-year-old woman without any prior disease was referred to our clinic for splenic incidentaloma. She had no symptom like fever or weight loss. Laboratory tests including complete blood count, blood serum chemistry were within normal limits. A computed tomography revealed a 5.3 cm sized heterogeneously enhancing highly vascularized lesion in spleen (Fig. 1A, B). 18-fluorodeoxyglucose positron emission tomography scan revealed a hypermetabolic lesion with a maximum standardized uptake value 5.6 and internal photon defect area in spleen (Fig. 1C).

Figure 1

Computed tomography (CT) and 18-fluorodeoxyglucose positron emission tomography (18-FDG PET) images of splenic incidentaloma. (A) Axial image of CT and (B) Coronal image of CT revealed a 5.3 cm sized heterogeneously enhancing highly vascularized lesion in spleen. (C) Axial image of 18-FDG PET scan revealed a hypermetabolic lesion with a maximum standardized uptake value (SUVmax) 5.6 and internal photon defect area in spleen.

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.

Figure 2

Histological view of the tumor of spleen. (A) A macroscopic cut surface shows a large multinodular lesion with focal hemorrhage. (B) The tumor (left area) shows heterogeneous appearance with well circumscribed border (Hematoxyling and Eosin [H&E], ×12). (C) The tumor shows whirling and fascicular growth pattern (H&E, ×200). (D) Dispersed epithelioid spindle shaped cells admixed with lymphoplasma cells are seen (H&E, ×400). (E) Neoplastic spindle cells show focal positivity for dendritic cell marker (cluster of differentiation 21, ×200). (F) Neoplastic spindle cells are positive for Epstein-Barr virus in situ hybridization (EBER, ×400).

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.