Fine needle aspiration cytology of follicular dendritic cell sarcoma - Report of a case with cytologic detection in an extranodal site

BACKGROUND: Follicular dendritic cell sarcoma (FDCS) is a rare malignancy o f accessory immune cells that can present in both nodal and extranodal site s. Previous cytologic case reports of FDCS have focused on fine needle aspi ration (FNA) findings in nodal sites with low grade morphology and indolent clinical courses. CASE: A 33-year-old female presented with a three-month history of abdomina l distention, early satiety and nausea. Initial imaging studies showed a la rge abdominal mass, with subsequent studies showing lung, liver and lymph n ode metastases. Examination of primary and metastatic tumors by a combinati on of conventional histology, immunohistochemistry and FNA demonstrated an extranodal intraabdominal follicular dendritic cell sarcoma. CONCLUSION: FDCS demonstrates a characteristic cytologic picture on FNA, wi th important cytologic features, including both syncytial and discohesive l arge epithelioid to spindled malignant cells with intranuclear inclusions, nuclear grooves and a prominent, mature, lymphocytic inflammatory component . No evidence of morphologic tumor progression was noted in comparison of p rimary and metastatic tumors. To aid in the cytologic distinction of FDCS f rom other similar-appearing neoplasms, we recommend acquisition of material for immunohistochemical studies, recognition of diverse clinical presentat ions (including extranodal and aggressive) and acknowledgment of the range of tumor morphologic grades.