Malignant solid and pseudopapillary tumor of the pancreas - Clinicohistological, immunohistochemical, and flow cytometric evaluation

Background/Aims: Solid and pseudopapillary tumor of the pancreas is a benign and low malignant potential tumor. Prognosis is good after surgical resection but its malignant potential is usually defined after metastasis. We compared benign and malignant cases with clinicopathological, immunohistochemical and DNA flow cytometric studies. Methodology: From January 1991 to July 2004, seven patients were found to have solid and pseudopapillary tumor of the pancreas at Taipei Veterans General Hospital. The paraffin sections were reevaluated with hematoxylin & eosin stain, immunohistochemical stains, and DNA flow cytometric studies. Results: It included 6 benign and one malignant case. The progesterone receptor, vimentin, neuron-specific enolase, and chromogranin A showed diffused positive stain in all cases. Estrogen receptor and P53 stain were negative in all 7 patients. Synaptophysin stain was negative in 6 no recurrence patients, but was positive only in the patient who suffered from recurrence. DNA flow cytometry showed diploid results in six non-malignant tumors. In the malignant patient, the tumor in the first operation showed diploid result, but tumors in second and third operations showed aneuploidy. Conclusions: Solid and pseudopapillary tumor of the pancreas should be considered as a potentially malignant disease in all patients and regular follow-up is mandatory.