Intra-abdominal follicular dendritic cell sarcoma with marked pleomorphic features and aberrant expression of neuroendocrine markers: report of a case with immunohistochemical analysis.

Follicular dendritic cell sarcoma (FDCS) is a very rare malignant tumor arising most frequently in lymph nodes with only few reports of extranodal locations. We report the case of a 35-year-old man with a large retroperitoneal mass. Histologically the tumor was composed of highly pleomorphic cells exhibiting some uncommon features such as an epithelioid appearance, cystic spaces, and multinucleated cells with morphologic features of emperipolesis. Immunohistochemically the neoplastic cells were immunoreactive for CD21, CD23 and CD35. A previously unreported expression of neuroendocrine markers (Synaptophisyn and Neuron-Specific-Enolase) was present. Ultrastructurally no neuroendocrine secretory granules were detected. FDCS can mimic a wide variety of other malignant tumors, and a correct diagnosis requires exclusion of other neoplasms and immunohistochemical confirmation.

Washed-biopsy cytology of abdominal lesions.

The accuracy of an alternative method of preparing cytologic smears from material collected under laparoscopic examination was studied. "Washed-biopsy" cytology was performed by saline solution lavage of the fragments using a cytocentrifuge. Rich and well-preserved cellularity was obtained. Among 51 cases, cytology revealed 12 benign, 3 suspicious and 36 malignant cases, including 9 true negatives, 3 false negatives and 36 true positives. Suspicious cases were excluded from the analysis. The sensitivity, specificity, positive and negative predictive values, and efficiency, when comparing the cytologic to the definitive diagnoses, were, respectively, 92.3%, 100.0%, 100.0%, 75.0% and 93.7%. We recommend the routine use of the washed-biopsy method in laparoscopic examinations to improve the accuracy of cytologic investigations.