|Year : 2018 | Volume
| Issue : 3 | Page : 219-222
Follicular dendritic cell sarcoma of axillary lymph node: A rare entity presenting with diagnostic challenge
Sandip Kumar Mohanty, Debahuti Mohapatra, Shirin Dasgupta, Pranita Mohanty, Kaushambi Chakraborty
Department of Pathology, IMS and SUM Hospital, Bhubaneswar, Odisha, India
|Date of Web Publication||17-Sep-2018|
Dr. Debahuti Mohapatra
Department of Pathology, IMS and SUM Hospital, Bhubaneswar, Odisha
Source of Support: None, Conflict of Interest: None
Follicular dendritic cell sarcoma (FDCS) originating from follicular dendritic cells is an uncommon proliferation of spindle to ovoid cells with morphological and immunophenotypic diversity. While most of the FDCSs are primary tumors of lymph nodes, at least one-third of them occur in extranodal sites. A 60-year-old male presented with right-side axillary swelling without systemic features; clinically and radiologically suspected as inflammatory lesion, but cytologically diagnosed as pleomorphic sarcoma. Microscopy revealed diagnostic challenge because of complex histomorphology and architecture which was pinpointed only after a battery of immunohistochemical (IHC) studies. Broad differential diagnosis both clinically and histomorphologically ranging from undifferentiated carcinoma, melanoma, to pleomorphic sarcoma creates diagnostic pitfall. Thus, IHC plays a major role in establishing this rare entity.
Keywords: Follicular dendritic cell sarcoma, lymph node, pleomorphic sarcoma
|How to cite this article:|
Mohanty SK, Mohapatra D, Dasgupta S, Mohanty P, Chakraborty K. Follicular dendritic cell sarcoma of axillary lymph node: A rare entity presenting with diagnostic challenge. J NTR Univ Health Sci 2018;7:219-22
|How to cite this URL:|
Mohanty SK, Mohapatra D, Dasgupta S, Mohanty P, Chakraborty K. Follicular dendritic cell sarcoma of axillary lymph node: A rare entity presenting with diagnostic challenge. J NTR Univ Health Sci [serial online] 2018 [cited 2019 Aug 17];7:219-22. Available from: http://www.jdrntruhs.org/text.asp?2018/7/3/219/241288
| Introduction|| |
Dendritic/reticulum cells are categorized into follicular dendritic cells, interdigitating dendritic cells, fibroblastic reticulum cells, and langerhans cells. Follicular dendritic cell sarcoma (FDCS) is a neoplastic proliferation of spindloid to ovoid cells morphologically and immunophenotypically showing features originating from follicular dendritic cells. FDCS was first described in 1986 by Monda et al. in a series of four cases with initial presentation of unilateral cervical adenopathy, as a nonlymphomatous primary lymph node malignancy. FDCS is classified under histiocytic and dendritic cell neoplasms by the World Health Organization Classification of Tumors. It accounts for only 0.4% of soft tissue sarcomas present in both nodal and extranodal tissues. It is an extremely unusual neoplasms presenting with clinical, diagnostic, and therapeutic challenge.
| Case Report|| |
A 60-year-old male patient presented with right-side hard, irregular, mobile axillary swelling measuring 6 × 5 cm since 5 months with no systemic manifestations. The overlying skin was unremarkable. Contrast-enhanced computed tomography scan showed a well-defined soft tissue density, necrotic mass in right axilla abutting pectoralis minor muscle and axillary vein.
Fine needle aspiration cytology revealed large, ovoid to spindle-shaped cells showing moderate to marked nuclear pleomorphism, irregular nuclear membrane, fine chromatin, moderate to abundant eosinophilic cytoplasm, and indistinct cell borders arranged in syncytial sheets, bundles, and fascicles [Figure 1]. Thus, diagnosis of pleomorphic sarcoma possibly rhabdomyosarcoma/poorly differentiated carcinoma was rendered.
|Figure 1: Cytomorphology of follicular dendritic cell sarcoma showing ovoid to spindle-shaped highly pleomorphic cells with admixture of binucleated R-S-like cells with moderate to abundant elongated cytoplasm (Diff Quik, ×400)|
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Wide local excision of the axillary tumor was done and sent for histopathology which revealed a single globular skin attached mass measuring (10 × 7 × 4) cm. Cut section showed a well-circumscribed grayish white, solid tumor measuring (7 × 5) cm with foci of hemorrhage and necrosis [Figure 2].
|Figure 2: Encapsulated specimen showing greyish white solid cut section with foci of hemorrhage and necrosis|
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Histopathology showed a thick fibrous capsule with a completely effaced lymph node architecture by tumor cells composed of oval to spindloid cells arranged in fascicles and diffuse sheets with extensive areas of necrosis. The spindloid cells exhibited moderate to marked nuclear pleomorphism, vesicular nucleus, prominent nucleoli in some with moderate to abundant eosinophilic cytoplasm having indistinct cell border. The mitosis was 9-10/10HPF. Admixture of lymphocytes, plasma cells, and histiocyte-like cells with few bi-nucleated and multinucleated R-S-like cells were also seen. Capsule and perinodal soft tissue were free of tumor [Figure 3].
|Figure 3: Photomicrograph showing sheets of pleomorphic spindloid to polygonal cells showing few bi- - and multinucleated R-S-like cells with admixture of lymphocytes and plasma cells (H and E, ×400)|
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Based on histomorphology, the diagnosis was malignant spindle cell neoplasm with possibilities of malignant peripheral nerve sheath tumor/malignant fibrous histiocytoma/amelanotic malignant melanoma suggested. Hence, battery of immunohistochemical (IHC) studies were carried out which showed strong positivity for vimentin, CD21, CD23, CD68, and S100; negativity for Desmin, MyoD1, HMB-45, high-molecular-weight cytokeratin, and EMA [Figure 4]. Thus, final diagnosis was high-grade nodal FDCS. After 1-year follow-up, no evidence of recurrence or metastasis was found.
|Figure 4: (a and b) The immunohistochemical markers shows diffuse strong cytoplasmic vimentin positivity (a) and CD21 positivity (b) (×400)|
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| Discusssion|| |
FDCS commonly presents as painless, asymptomatic, slowly growing cervical lymphadenopathy; characterized by female predominance often associated with systemic manifestation autoimmune diseases such as paraneoplastic pemphigus and myasthenia gravis. Most of them occur as nodal presentation, but approximately one-third occur in extranodal sites such as skin, mediastinum, gastrointestinal tract, and soft tissue. FDCS is frequently associated with complex cytogenetic abnormalities. Polymerase chain reaction studies showed strong BRAF V600E mutation in 40% cases of inflammatory pseudotumor such as FDCS and 18.5% in conventional FDCS.
Grossly, they are characterized by well-circumscribed/encapsulated bosselated masses that are solid with pink white to tan grey cut surface. The size varies from 1 to 20 cm, extranodal tumors being larger than nodal tumors with areas of hemorrhage and necrosis.
Histopathology sections demonstrate spindle cell proliferation with varied architectural pattern varying from storiform to whorled, bundles, fascicles, and sheets. Prominent lymphocytes are present between tumor cells which are predominantly B lymphocytes and scattered multinucleated cells. The tumor cells have elongated to ovoid nuclei with thin nuclear membrane, granular chromatin, and small nucleoli with mitotic figure (1-10/10HPF). Inflammatory pseudotumor such as follicular dendritic cell tumor is a variant of FDCS with distinct cytological features of fascicular arrangement of ovoid to spindle-shaped cells with vesicular nuclei, variable nuclear atypia, occasional R-S-like cells admixed with abundant lymphocytes and plasma cells, exclusively located in liver and spleen, showing EB virus positivity by fluorescence in situ hybridization study. Typical cytomorphology of FDCS is often difficult, which needs further confirmation by IHC studies. IHC shows strong positivity for CD21, CD23, vimentin, and EGFR. It is variably positive for EMA, S100, CD68, CD34, CD1a, CD3, CD30, CD20, and CD79a. HMB45, Desmin, and cytokeratin are negative. Ki67 ranges from 1% to 25%.
About 30%–58% of cases of FDCS are misdiagnosed due to varied histomorphology and IHC markers . Differential diagnoses include metastatic undifferentiated carcinoma, malignant melanoma, malignant peripheral nerve sheath tumor, and malignant fibrous histiocytoma. Follicular dendritic sarcoma is often confused with metastatic undifferentiated carcinoma because of spindle cell morphology and variable number of inflammatory cells, but is differentiated by EMA and CK positivity, and CD 21 negativity. Malignant melanoma especially amelanotic variant shows similar diverse morphology and architecture to FDCS but are HMB45-positive. Dedifferentiated Malignant peripheral nerve sheet tumor is confused with FDCS having similar morphology and S100 positivity but differentiated by CD 21 negativity. Thus, FDCSs have variable clinical course. Nodal tumors are indolent with low metastatic rate, whereas extranodal tumors are high grade often with metastasis to liver, lungs, and lymph nodes. Unfavorable prognostic factors are large tumor size >6 cm, coagulative necrosis, mitosis >5/10 HPF, significant cellular atypia with intra-abdominal location, and capsular invasion.,, The mortality is >20% after protracted course. Adequate surgery is the only treatment of early/low-grade FDCS, whereas the role of adjuvant therapy is indicated only in tumors with adverse pathological features and recurrent and unressectable tumors.
FDCS has variable behavior. Though previously known to be of low-grade malignancy, now based on prognostic factors the tumor can behave in an aggressive fashion showing recurrence, metastasis, and high mortality. Thus, the awareness of this rare entity showing clinical and histopathological diversity is often confirmed by battery of IHC markers supplemented with cytogenetic studies. This aids in solving the treatment variability depending on site, cell of origin, and various prognostic factors.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]