Introduction:
Follicular dendritic cell sarcomas are cancerous tumors arising from the follicular dendritic cells. They are immune cells involved in antigen presentation and are formed in the lymphoid tissues, unlike the dendritic cells formed from the bone marrow. It has a rare occurrence and a high potential for recurrence and metastasis (spread of cancer to a distant location).
Microscopically follicular dendritic cell sarcoma is similar to other connective tissue cancers like melanoma, non-Hodgkin's lymphoma, undifferentiated carcinomas, and diseases of dendritic cells. Thus a differentiation based on the histological picture is difficult for these diseases. Therefore, diagnosis of follicular dendritic cell sarcoma is based on the morphology of cells and immunohistochemical assay (lab tests that use antibodies to identify specific antigen markers for confirming diseases).
Patients with localized follicular dendritic cell sarcomas are often treated with radicular resection. Radiotherapy on the lesions did not show any significant survival outcomes. In unresectable tumors and metastasis, chemotherapy is indicated. An optimal chemotherapeutic regimen has yet to be determined for the treatment of follicular dendritic cell sarcoma. The agent used for treating malignant lymphoma and soft tissue sarcoma is also used here.
What Are the Morphological Characteristics of the Cells in Follicular Dendritic Cell Sarcoma?
The follicular dendritic cells are spindle or ovoid-shaped cells arranged into whorls, fascicles, nodules, or diffuse sheets. The tumor tissue often contains lymphoplasmacytic infiltrates. The cancer cells in follicular dendritic cell sarcoma present markers like
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CD21 (a protein involved in the complement system and expressed in normal and abnormal follicular dendritic cells).
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CD23 (it acts as a protein receptor for IgE antibodies).
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CD35 (expressed by follicular dendritic cells and anti-CD35 is a marker for follicular dendritic cell sarcoma).
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Clusterin (a protein associated with apoptosis and clearance of cellular debris).
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Fascin (it is an actin-building protein).
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Podoplanin (a protein expressed by lymphatic endothelial cells).
What Are the Common Locations for Follicular Dendritic Cell Sarcoma in Human Body?
The follicular dendritic cell sarcoma commonly develops in the lymphoid tissues and lymph nodes and is referred to as nodal cancer. However, 30 out of every 100 cases show tumorous growth elsewhere in the body, such as
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Head and neck region.
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Digestive system (stomach and bowel).
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Spleen.
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Skin.
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Lungs.
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Liver.
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The central area of the chest.
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Mediastinum (space between the lungs).
The tumors that grow outside the lymph nodes are called extranodal follicular dendritic cell sarcomas.
What Are the Causes of Follicular Dendritic Cell Sarcomas?
The exact cause of follicular dendritic cell sarcoma is unknown to date. In addition, the rare incidence of the disease leaves only a few case reports and data, which makes it challenging to find a common link. Some studies have linked the development of the tumor to Castleman's disease, in which a non-cancerous benign tumor develops in the lymph nodes. Some other studies have revealed the role of the Ebstein-Barr virus in developing follicular dendritic cell sarcomas in the liver and spleen. However, the exact mechanism needed to be clarified.
What Are the Clinical Features of Follicular Dendritic Cell Sarcomas?
The symptoms presented by the affected patients depend upon the location of follicular dendritic cell sarcomas. The most commonly seen sign is the painless swelling of the lymph glands of the neck. A swelling can develop in any part of the lymphatic system, but the neck is the common site. The tumors are described as indolent, meaning they are slowly growing tumors. The commonly observed symptoms are
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Cough.
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Difficulty in swallowing.
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Malaise (tiredness).
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Weight loss.
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Abdominal pain.
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Painless swellings.
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Fever with high temperature.
Patients with tumors outside the head and neck region show organ-specific symptoms.
How Is Follicular Dendritic Cell Sarcoma Diagnosed?
A definite diagnosis is made by biopsy of a segment of the tumor. Microscopic examination of the tumor cells' morphological features will help diagnose to some extent. However, the histological feature of the cancer is quite similar to that of lymphomas and connective tissue sarcomas, which makes the diagnosis difficult. Numerous tests can be employed to diagnose the tumor. These include
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Computed tomography (CT) scan.
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Positron emission tomography (PET scan).
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Blood Tests
Immunohistochemical staining of the tumor samples will help in identifying the tumor markers. Specific proteins like CD21, CD23, and CD35 are the most commonly observed markers in follicular dendritic cell sarcomas. Additional proteins observed include fascin, clusterin, and podoplanin. Therefore, identification of the tumor markers will help in diagnosing the disease.
What Are the Treatment Approaches for Follicular Dendritic Cell Sarcoma?
The treatment approach selected by the physician depends on certain factors like
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The size of the cancerous growth and the extent of spread to other parts of the body.
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The rate of growth of the tumor.
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General health and fitness of the patient.
After evaluating the factors, the physician will determine whether the patient requires surgical excision of the tumor, followed by chemotherapy and radiotherapy. Patients treated with surgery alone showed a high rate of recurrence of the tumor.
Chemotherapeutic agents used are the ones employed in the treatment of similar neoplasms like malignant lymphomas and other soft tissue neoplasms. Using a chemotherapeutic regimen for another disease was considered a doubtful way to treat the condition. Further studies suggested that surgical excision followed by cytotoxic drugs yielded better outcomes. All the advances in the management of follicular dendritic cell sarcomas come from the development of better treatment modalities for other similar cancers.
Conclusion:
The above review shows that follicular dendritic cell sarcoma is an uncommon neoplasm of unknown etiology. It has microscopic features similar to other connective tissue tumors. However, it can be differentiated by immunohistochemical analysis to identify protein markers. The tumor has a high incidence of recurrence after surgical excision and has a high metastasizing capacity. Since the reported cases of follicular dendritic cell sarcomas are very few in the medical literature, an optimal chemotherapeutic regimen could not be evaluated exclusively for the tumor. Further studies and research are needed to identify the exact cause and mechanism of the neoplasm and find the best medical intervention possible to yield better outcomes.
