Journal of Cancer Research and Therapeutics

: 2012  |  Volume : 8  |  Issue : 2  |  Page : 306--307

Follicular dendritic cell sarcoma: A diagnostic challenge !

Ajay Malik1, Ajit Veniyoor2, Barnard Fanthome3, Vibha Dutta1,  
1 Department of Pathology, AFMC, Pune, India
2 Medical Oncologist, Oman
3 Consultant Onco-Surgery, Mumbai, India

Correspondence Address:
Ajay Malik
Department of Pathology, AFMC, Pune


Follicular dendritic cell sarcoma (FDCS) is a spindle cell neoplasm of histiocytic-dendritic cells origin. It is known to occur in lymph nodes and rarely has been reported in extranodal tissues like head and neck, mediastinum and gastrointestinal tract. We herein report the first FDCS arising from anal canal in a 56-year-old man. The tumor was composed of bland short spindle cells in focal whorl formation with interspersed few lymphocytes. The tumor cells were classically positive for CD21, CD23, CD35 and vimentin. Despite its misleading morphology, immunohistochemistry helped us to reach a conclusive diagnosis for relevant therapy.

How to cite this article:
Malik A, Veniyoor A, Fanthome B, Dutta V. Follicular dendritic cell sarcoma: A diagnostic challenge !.J Can Res Ther 2012;8:306-307

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Malik A, Veniyoor A, Fanthome B, Dutta V. Follicular dendritic cell sarcoma: A diagnostic challenge !. J Can Res Ther [serial online] 2012 [cited 2021 Dec 1 ];8:306-307
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Follicular dendritic cells, also called dendritic reticulum cells, are seen forming the network in the germinal centers of the lymph nodes. They present antigens to the B lymphocytes so that the memory B cells and plasma cells can be generated. [1],[2] The tumors of these cells are called follicular dendritic cell sarcomas (FDCS), which are rare and also low compared to intermediate grade neoplasms, which may recur after the surgery. These tumors not only can arise mainly in head and neck region but also in any visceral organ. [3],[4],[5] To add to the existing available literature, we present here a case of FDCS of anal canal, with complaints of constipation and bleeding per rectum.

 Case Report

Clinical Features

An averagely built, 56-year-old male reported to the hospital with constipation, dull aching sensation in the perineum and recurrent mild bleeds while defecating. In addition, a history of weight loss of 5 kg over last six months was elicited. He was admitted to the hospital with above complaints. On physical examination, he was found to be mildly anemic.

Pathological Features

We received an abdominoperineal resected specimen with a bulging submucosal growth in the lower anal canal, measuring 7 × 4 cm in size. The growth specimen was bisected and revealed a fleshy pinkish white, lobulated cut surface with nodule formation and an occasional area of hemorrhage [Figure 1]a. The tumor appeared to have a capsule focally. Histopathological examination of tissue from the tumor revealed a nodular architecture pattern. The nodules were separated by thin, incomplete fibrovascular septae. The nodules showed presence of whorls and fascicles of short spindle to blunt ovoid cells with eosinophilic cytoplasm, oval to spindle shaped nuclei with thin nuclear membrane and the inconspicuous nucleoli [Figure 1]a. In between the nodules of tumor cells, focal mild lymphocytic infiltrates were noted. Few lymphocytes were also seen in between tumor cells in the nodules and perivascular location [Figure 1]b. An occasional mitotic figure could be appreciated. Focal tissue breakdown and small areas of necrosis were also seen. {Figure 1}

Immunohistochemistry Findings

The tumor cells showed a diffuse cytoplasmic positivity to follicular dendritic cell markers, namely, CD21, CD23, CD35 and vimentin (all from DAKO) as shown in [Figure 1]. The tumor cells were strongly positive for CD21, CD23 and vimentin but focally positive for CD35. The tumor cells lacked cytokeratin, S-100, p63, smooth muscle actin (sma), CD3, CD20, CD34, CD45, CD68 and CD117. Infiltrating lymphocytes were mainly positive for CD20.


FDCS is a rare tumor of dendritic-histiocytic cell origin. Monda et al first described FDCS in 1986 and Chan et al reported the first extranodal tumor in 1994. [1],[2],[4] Since then the tumor has been reported in various sites like palate, tonsils, stomach, mesocolon, pancreas, breast, small intestine. [1],[2],[4],[5],[6],[7] The morphology of our case is typical of FDCS, although various studies have reported atypical presentations in the form of multifocal disease, increased mitoses, giant cell transformation and wide areas of necrosis. [1],[2],[3],[4],[5],[6],[7],[8]

The tumor is considered to be a low grade neoplasm with a tendency to recur. More aggressive behavior has been noted by some, when the tumor is found in the intra-abdominal location. The explanation given is that here tumors may grow larger than their counterparts elsewhere without detection, have a high mitotic rate, pronounced cellular atypia, and cell necrosis. [3] Current therapeutic protocols dictate that the best course for a FDCS is surgery without any chemotherapy or radiotherapy.

The diagnosis was challenging as the neoplasm looks very similar to other tumors of the gastrointestinal tracts like gastrointestinal stromal tumor (GIST), solitary fibrous tumor, inflammatory myofibroblastic tumor, smooth muscle and fibrous tumors, fibrohistiocytic tumor, metastatic sarcoma, undifferentiated carcinoma and also melanoma at times. The problem multiplies when the tumor in question is situated or is arising in extranodal tissues. Wang et al found that more than half of the reported cases fall in extranodal group. [2] They also tried looking for presence of / association with EBV in extranodal group of tumors. However, this has not been substantiated till date. On morphology, we initially thought it to be a GIST and investigated on those lines. GIST cells are a little less eosinophilic and may show differentiation towards smooth muscle cells, epithelioid or neurogenic appearance. GISTs may also show background myxoid change. To our surprise, finally it turned out to be a FDCS, after the detailed immunohistochemistry markers were studied. Immunohistochemical study in our case was helpful as FDCS is consistently negative for CD34, CD117 (positive in GIST), S-100 (positive in Melanoma and interdigitating reticulum cell tumors), cytokeratin (positive in sarcomatoid carcinoma), CD45, CD68 (positive in histiocytic tumors), p63 and sma (positive in smooth muscle tumors).

On considering the possibility of a FDCS, the diagnosis requires the application of immunohistochemistry with antibodies to CD21, CD23, and CD35. These antibodies are hardy and work well on heat induced antigen retrieval technique using microwave on paraffin sections. These three are said to be relatively specific markers for follicular dendritic cells along with podoplanin and clusterin. [8]

To summarize, we have described a rare and unusual case of an FDCS presenting as an anal canal submucosal lobulated tumor in a 56-year-old man. We have also demonstrated that FDCS should be considered in cases of CD34 and CD117 negativity in a spindle cell tumor of the anal canal. An extensive panel of antibodies should be done in such cases. Additional studies for a racial / genetic etiology are needed especially to look for the role of EBV.


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