Mediastinal follicular dendritic cell sarcoma: a rare, potentially under-recognized, and often misdiagnosed disease

Abstract

BackgroundMediastinal follicular dendritic cell sarcoma (FDCS) is extremely rare. Due to potential under-recognization of this disease, it happens to be misdiagnosed, especially on core needle biopsy. We report 3 cases of mediastinal FDCS and provide a literature review to improve better understanding of the tumor and to reduce misdiagnosis.MethodsThree cases of mediastinal FDCS in our clinic practice were studied, including their core needle biopsy and resected specimens, and those cases reported previously in English literature were retrieved and analyzed.ResultsThe core needle biopsy of case 1 showed a tumor reminiscent of classical Hodgkin’s lymphoma (CHL), while the resected mass was finally diagnosed with FDCS combined with hyaline-vascular Castleman’s disease. Both the biopsy and resected tissue of case 2 were constitutive of the clear epithelioid cells with marked atypia. In both cases, definitive diagnoses were not made on core needle biopsy. In case 3, there were some areas morphologically similar to CHL, and some areas contained ovoid to spindle-shaped tumor cells with fascicular pattern. The analysis of 43 cases of mediastinal FDCS showed the age of patients were from 16 to 76 years old, the male to female ratio was 1.5:1, the maximal tumor diameters were 3–17 cm. 18 cases were underwent preoperative biopsy, whereas 15 (83.3%) of which were misdiagnosed initially, often as lymphoma. 32 patients had available follow-up data, the rates of recurrence, metastasis, and mortality were 12.5, 18.8 and 28.1%, respectively. Current limited data suggested no statistical differences between adverse prognosis and gender, age, tumor size, necrosis, or different therapeutics, respectively.ConclusionsMediastinal FDCS is a rare malignancy that has yet not been fully understood and been often misdiagnosed, particularly when making a diagnosis on core needle biopsy. Increased awareness of this enigmatic tumor is crucial to avoid diagnostic pitfalls.

Nodal follicular dendritic cell sarcoma with four atypical histomorphologic features: an unusual case report

“…Most notably, this FDCS case demonstrates a spectrum of morphologies. The histomorphology of FDCS is usually heterogeneous and has been known to show epithelioid or pleomorphic tumor cells [5–8], myxoid stroma [9, 10], osteoclastic giant cells [11, 12], and CHL-like features [6, 13], among others. However, in this case, the four atypical histopathologic morphologies were all present within the same tumor, which has not been previously reported.…”

“…The first preoperative biopsy may have involved the resection of just the lymph node containing invasive epithelioid cell nests, which resulted in the initial misdiagnosis. The areas similar to ALCL or CHL but that were CD30-positive by IHC (it has been reported that a few FDCS could express CD30 [6, 13]) are another point of diagnostic importance. The treatment of FDCS is typically surgical resection, whereas lymphoma is treated with chemotherapy and radiation.…”

“…However, Spatola C et al [15] demonstrated that adjuvant therapy could strengthen the local control of the disease; Pang J et al [16] also showed that surgery alone was associated with higher rates of relapse than postoperative adjuvant therapy. Considering the adverse factors [2, 13] in our case including that the maximum tumor diameter was ≥6 cm and that coagulative necrosis, cells with marked atypia, and a focally high mitotic count (> 10/10 high-power fields (HPF)) were observed, the patient received chemotherapy and radiotherapy after radical resection. The patient’s condition was initially well controlled until premature discontinuation of chemotherapy resulted in relapse; subsequent radiation did not effectively control disease progression.…”

Clinicopathological characteristics of extranodal follicular dendritic cell sarcoma: A report of two cases

“…Histiocytic neoplasms are a type of tumor that arise from the monocyte-macrophage system, including dendritic cells (DCs), macrophages and sometimes histiocytes ( 1 , 2 ). DC tumors are associated with certain types of antigen-presenting cells ( 2 ).…”

“…FDCS consists of a neoplastic proliferation of spindled to ovoid cells exhibiting morphological and immunophenotypic features of FDCs ( 1 ). Misdiagnosis occurs frequently, due to the fact that it has the same micromorphology as other common neoplasms, such as other types of sarcoma and lymphoma ( 2 , 3 ).…”