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Cytomorphology, ultrastructural, and cytogenetic findings in follicular dendritic cell sarcoma: a case report
Xiaohong I Wang1, Songlin Zhang, Jaiyeola O Thomas
1Department of Pathology, Louisiana State University Health Sciences Center, 1501 Kings Highway, Shreveport, Louisiana 71130, USA.
Insights
Follicular dendritic cell (FDC) sarcoma diagnosis is challenging via cytology alone. Immunohistochemistry and ultrastructural studies are crucial for accurate FDC sarcoma diagnosis, especially in rare neck masses.
Area of Science:
- Oncology
- Cytopathology
- Surgical Pathology
Background:
- Follicular dendritic cell (FDC) sarcoma is a rare neoplasm with an indolent course.
- Misdiagnosis of FDC sarcoma is common on initial aspiration cytology.
- Early and accurate diagnosis is critical for effective patient management.
Observation:
- A 26-year-old woman presented with a slow-growing neck mass.
- Cytology revealed epithelioid cells with lymphoid background.
- Immunohistochemistry confirmed tumor cells positive for CD21, CD35, CD23, and fascin.
Findings:
- Fine needle aspiration cytology findings for FDC sarcoma can be ambiguous.
- Immunohistochemistry is essential for confirming FDC sarcoma diagnosis.
- Ultrastructural studies can aid in definitive diagnosis.
Implications:
- Preoperative diagnosis of FDC sarcoma via cytology is difficult.
- Accurate diagnosis relies heavily on immunohistochemical markers.
- Integrated diagnostic approaches improve FDC sarcoma detection.
Background:
Follicular dendritic cell (FDC) sarcoma is a rare low-to-intermediate grade malignant dendritic cell neoplasm that often has an indolent clinical course. FDC sarcomas are often misdiagnosed on aspiration cytology.
Case:
A 26-year-old woman presented with a solid, slowly growing, painless mass in her right neck for 3 months. Computed tomography revealed a 3.6-cm, well-defined homogenous solid mass located posterior to the mandible and submandibular glands. Fine needle aspiration cytology revealed many large, spindle to ovoid epithelioid cells in singles, small clusters, and syncytial sheets with moderate to abundant cytoplasm, indistinct cell borders, irregular nuclear membrane, fine to vesicular chromatin, and conspicuous nucleoli. The background contained many small mature lymphocytes intimately mixed with large epithelioid tumor cells. Tumor cells were strongly positive for CD21, CD35, CD23, and fascin. Diagnosis of FDC sarcoma was rendered; follow-up surgical resection and ultrastructural study confirmed the diagnosis. The cytogenetic study showed a normal female karyotype 46,XX.
Conclusion:
Although the cytomorphology of FDC sarcoma is characteristic, a preoperative diagnosis of FDC sarcoma based on fine needle aspiration cytology is very challenging, if not impossible. Immunohistochemistry is always necessary for rendering and/or confirming the diagnosis, and ultrastructural studies are helpful.
