A Cytological Review of Follicular Dendritic Cell-Derived Tumors with Emphasis on Follicular Dendritic Cell Sarcoma and Unicentric Castleman Disease

Cytological diagnosis of follicular dendritic cell sarcoma with a unique pattern of D2-40 immunoexpression

Fine needle aspiration procedure is routinely used for cytological diagnosis of nodal or extra nodal lesions. Follicular dendritic cell sarcoma (FDCS) is a rare mesenchymal neoplasm arising from follicular dendritic cells of lymphoid follicles at nodal and extranodal sites. Multimodal therapies have emerged for FDCS, necessitating its accurate pathologic diagnosis with additional ancillary testing for directing clinical management. By immunohistochemical analysis, FDCS is positive for the complement receptors CD21, CD23, and CD35. In addition, D2-40 is reported to be highly sensitive for FDCS with a strong membranous pattern of expression. In this study, we present the cytological diagnosis of a case of FDCS in retroperitoneal lymph nodes with an emphasis on a unique staining pattern of D2-40 which showed a strong nuclear pattern in tumor cells comparable to the membranous pattern of D2-40 on the control tissue and other surgical cases of FDCS in our comparative study.

Follicular Dendritic Cell Sarcoma of the Parotid Gland: A Case Report and Review of Literature

Follicular dendritic cell sarcoma of the parotid gland is an extremely rare tumor, with only six cases reported in the literature. A 51-year-old female had a 3.0 cm tumor resected from the right parotid gland. The tumor exhibited solid sheets, whorls, fascicular pattern, and syncytium appearance with an indistinct cell border. The lymphocytic infiltrate was sprinkled throughout the neoplasm, with focal prominent perivascular cuffing. Immunohistochemically, it was positive for follicular dendritic cell markers CD21, CD23, and CD35. We aim to enhance the understanding of this neoplasm and alert pathologists to this rare entity in this region to avoid misdiagnosis.

Fine-Needle Aspiration of Sarcomas Metastatic to Lymph Nodes: A Cytomorphologic Study over a 10-Year Period

INTRODUCTION

Metastasis of sarcomas to lymph nodes is an uncommon event in its natural history. We aimed to present our experience with fine-needle aspiration (FNA) of metastatic sarcomas to lymph nodes over a 10-year period.

MATERIAL AND METHODS

The cytopathology archives were searched for FNA of lymph nodes involved by metastatic sarcomas. Available clinicopathologic data were recorded. All slides were retrieved and reviewed.

RESULTS

Thirty-three lymph nodes, from 30 patients, with metastatic soft tissue sarcomas were identified. The lymph node metastases occurred in 16 males and 14 females (median age, 56 years). The size of the lymph nodes ranged from 1.2 to 7.5 cm (median size, 2.9 cm). The inguinal lymph nodes were the most commonly involved nodes, followed by thoracic and cervical neck nodes. The most common metastatic soft tissue sarcoma encountered was Kaposi sarcoma (n = 7, 23.3%), followed by angiosarcoma (n = 6, 20%) and rhabdomyosarcoma (n = 6, 20%). The most common site of primary soft tissue sarcoma was the head and neck (n = 8, 26.6%), followed by lower extremity (n = 7, 23.3%). The initial diagnosis of sarcoma was established in 6 cases. Seventen patients had metachronous involvement of lymph nodes, while the remaining patients had synchronous involvement. Seventen patients died of disease, and the survival after lymph node metastasis ranged from 1 to 43 months.

CONCLUSION

FNA is an accurate and effective method in the diagnosis of metastatic sarcoma to lymph nodes. Knowledge of clinical findings and primary tumor diagnosis along with careful assessment of the cytomorphology is extremely helpful for an accurate diagnosis of metastases.

A stepwise approach to fine needle aspiration cytology of lymph nodes

The cytological diagnosis of lymph node lesions is extremely challenging because of the diverse diseases that cause lymph node enlargement, including both benign and malignant or metastatic lymphoid lesions. Furthermore, the cytological findings of different lesions often resemble one another. A stepwise diagnostic approach is essential for a comprehensive diagnosis that combines: clinical findings, including age, sex, site, multiplicity, and ultrasonography findings; low-power reactive, metastatic, and lymphoma patterns; high-power population patterns, including two populations of continuous range, small monotonous pattern and large monotonous pattern; and disease-specific diagnostic clues including granulomas and lymphoglandular granules. It is also important to remember the histological features of each diagnostic category that are common in lymph node cytology and to compare them with cytological findings. It is also essential to identify a few categories of diagnostic pitfalls that often resemble lymphomas and easily lead to misdiagnosis, particularly in malignant small round cell tumors, poorly differentiated squamous cell carcinomas, and nasopharyngeal undifferentiated carcinoma. Herein, we review a stepwise approach for fine needle aspiration cytology of lymphoid diseases and suggest a diagnostic algorithm that uses this approach and the Sydney classification system.