Fine-needle aspiration of intra-abdominal desmoplastic small cell tumor

The cytologic features of four cases of histologically confirmed intra-abdominal desmoplastic small cell tumor (DSCT) that occurred in males between 18-27 yr of age are presented. Smears showed small cells with scant cytoplasm which were primarily arranged in loosely cohesive clusters. Nuclei were oval to round with evenly distributed, finely granular chromatin and inconspicuous nucleoli. As is typical of DSCT, the cells strongly expressed keratin and desmin in all cases. In the one case studied by electron microscopy, it was demonstrated that the cells were joined by small junctions and contained paranuclear aggregates of intermediate filaments. The absence of the characteristic desmoplastic stroma in DSCT aspirates and the nonspecific cytologic features of this small round-cell tumor (SRCT) made cytologic interpretation difficult. Cytopathologists should be aware of this entity so that DSCT is included in the differential diagnosis of SRCTs that occur in intra-abdominal sites. A panel of markers that includes keratin and desmin should be used to assist in the identification of DSCT.