The patient received six courses of chemotherapy. A post-chemotherapeutic 18-FDGPET/CT performed six months after diagnosis showed a partial metabolic response and a macroscopic mass was still visible on CT after the first four cycles (Fig. 4A), and a complete metabolic and radiologic response at the end of the first line (Fig. 4B and C).
At nine months, recurrence was noted in the peripancreatic region on 18-FDGPET/CT. She was further treated by a second line chemotherapy with etoposide, cisplatine, ARA-C, and prednisone (ESHAP). The 18-FDGPET/CT performed after four courses showed a complete metabolic response. She received one more course of ESHAP followed by a bone marrow allotransplantation (BHS2 protocol).
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BHS2 is the reduced intensity conditioning regimen received by the patient consisted in (total lymphoid irradiations) TLI 8 Gy (80c Gy/day during 10 days) from day-11 to day-7 and from day-4 to day-0, and rabbit ATG (Thymoglobulin Genzyme) 1.5 mg/kg/day during five days from day-11 to day−7. GVHD prophylaxis consisted in cyclosporine (Neoral), six months post transplantation and mycophenolate mofetil acid, 1 gr bid (CellCept) during 45 days.21
At 24 months (eight months after bone marrow allotransplantation), another recurrence occurred at the same site on 18-FDGPET/CT. The patient received two lymphocytes infusions, from her previous donor, without therapeutic effectiveness.
Then, we proceeded by administration of a third line chemotherapy with gemcitabine, navelbine, and dexamethasone. The 18-FDGPET/CT performed after four courses showed a partial metabolic response. She received two additional courses in consolidation.
18-FDGPET/CT performed after six courses showed a complete metabolic response.
At the 29-month follow-up, she presented with a complete metabolic response.
Discussion
FDCS belong to dendritic cell sarcoma group with interdigitating dendritic cell sarcoma (IDCS) and fibroblastic reticular cell tumor (FRCT).
FDCS is a very rare neoplasm of antigen presenting cells of the B-cell follicles of lymphoid organs. FDCS affects mainly young adults without gender predilection.2 Recurrence is frequent with local recurrence and distant metastases reported in about 40% of patients.3 FDCS are probably underdiagnosed because of its rarity and uncommon histological features.
At histology, differential diagnoses are thymoma-like, meningioma-like tumors and malignant fibrous histiocytoma. Immunohistochemical analyses are fundamental to confirm the diagnosis. Tumor cells show phenotype of non neoplastic follicular dendritic cells and are thus positive for markers CD21, CD23, and CD35.2–4
In addition, they are usually positive for desmoplakin, vimentin, fascin, and HLA-DR. Tumors cells are variably positive for S-100-protein and CD68 and they are consistently negative for CD1a, lysozyme, myeloperoxidase, CD34, CD3, CD79a, CD30, HMB-45, and cytokeratins.
Most of the cases reported in the literature have involved lymph nodes of the neck, mediastinum, and axilla. Approximately one third of the cases were located in extranodal sites, such as liver, tonsil, and intra-abdominal soft tissue.4–8,13 Intra-abdominal location is associated with higher recurrence, metastasis, or mortality rate.2,3,13
