Cytological diagnosis of follicular dendritic cell sarcoma: A case report and review of literature

Abstract

atypical ones were noted. On immunohistochemistry, the tumour cells were diffusely positive for CD21, CD23 and vimentin and focally positive for SMA while, were negative for cytokeratin (AE1/ AE3), EMA, p63, CK8/18, PAX-8, S-100, CD68, desmin, CD31, CD30, Alk-1, CD1a, CD20, MUM1, LCA (CD45) and synaptophysin and CD43. Immunohistochemistry with CD21 and CD23 performed on cell block retrospectively also showed diffuse positivity (Figure 2C,D). Based on the histomorphological and immunohistochemical findings, a diagnosis of FDCS was rendered.The smears from the left thyroid showed cytomorphological features consistent with benign follicular nodule. | 465 neoplastic cells intimately admixed with mature lymphocytes is also the tell-tale feature of FDCS on FNA. However, other neoplasms that share this feature are thymoma, lymphoepithelioma-like carcinoma, seminoma, lymphoma, nasopharyngeal carcinoma and medullary carcinoma of breast. Presence of neoplastic cells in syncytial aggregates and singly dispersed, coupled with oval to spindled morphology brings in the differentials of melanoma, gastrointestinal stromal tumour and ectopic meningioma (if they show whorling pattern), but these lack the lymphocytic infiltrate. Another distinctive cytological feature highlighted by few reports is the presence of cytoplasmic processes. 2,8,12,13,15,19,21 Cytoplasmic processes are seen in many tumours, such as nerve sheath tumours, smooth muscle tumours, gastrointestinal stromal tumour and fibrosarcoma, are usually bipolar, while, multipolar interconnecting processes characterise FDCS. 13,15,17,21 However, this feature was lacking in the present case. Cells resembling Reed Sternberg (RS) cells were noted in some reports leading to consideration of lymphoma. 10,17,20 The present case did show multinucleated giant cells but lacked RS cells. The cytological appearance of interdigitating reticulum cell sarcoma and fibroblastic reticular cell tumour are similar to FDCS, thus making it impossible to differentiate. Since cytomorphology alone is often misleading, immunocytochemistry or immunohistochemistry on cell blocks play a crucial role in the diagnosis. Follicular dendritic cell sarcoma cells are typically positive for CD21, CD23, CD35, clusterin, c-synuclein, CXCL13 and podoplanin (D2-40). They also stain for vimentin, EMA, S100 and CD68, which can lead to diagnostic errors if the dendritic cell markers are not performed. They are negative for cytokeratin, CD1a, Lysozyme, MPO, CD34, CD3, CD79a, HMB45, CD34, CD30, HMB-45 and Desmin. 1,24 Aberrant expression of TTF-1, neuroendocrine markers and cytokeratin have also been reported. 25 Recently, two novel, highly sensitive and specific markers for FDCS, Follicular dendritic cell secreted protein and serglycin have been identified. 26 The inflammatory pseudotumour-like FDCS is a distinct variant of FDCS which mimic inflammatory pseudotumour and has a predilection for involvement of intra-abdominal sites. They have spindled tumour cells with a dense lymphoplasmacytic infiltrate in the backg...

Follicular dendritic cell sarcoma in the right chest wall

“…FDCS occurs typically in young to middle-aged patients (average age: 44 years) with no gender distinction. [ 1 ] It can be easily confused with other diseases, such as inflammatory pseudotumor, angiosarcoma, hemangioendothelioma, metastatic carcinoma, and malignant fibrous histiocytoma. [ 10 ] Tumor size and growth patterns are closely related to the disease site.…”

“…Follicular dendritic cell sarcoma (FDCS), also known as dendritic cell sarcoma with unclear pathogenesis, is a relatively rare malignant tumor originating from follicular dendritic cells (FDC) at both nodal and extra-nodal sites FDC. [ 1 ] FDC are located in the germinal centers of primary and secondary lymphoid follicles and play an important role in antigen presentation to B cells to promote their maturation. [ 2 ] Seventy percent of FDCS tumors occur in mediastinal or axillary lymph nodes.…”

“…[ 3 ] The remaining 30% develop in other areas, such as the thyroid, breast, retroperitoneum, oral cavity, nasopharynx, parotid gland, lung, liver, spleen, pancreas, gastrointestinal tract, and intracranial areas. [ 1 ] FDCS arising from the chest wall is extremely uncommon and only 2 cases have been reported to date. [ 4 , 5 ]…”

Role of Adjuvant Chemotherapy in Extranodal Follicular Dendritic Cell Sarcoma

“…However, one-third of cases are extranodal in origin, mainly involving the head and neck sites, gastrointestinal tract, soft tissue, and mediastinum. 4,15…”

“…Recently, 2 novel, highly sensitive and specific markers for FDCS, follicular dendritic cell–secreted protein and serglycin, have been identified. 15…”