Comparision Of Clinical And Pathological Features Between SPT And PET And The Significance Of Secretagogin In Differential Diagnosis

Purpose:To explore clinical, histological and immunohistochemical essential points in diagnosis between solid pseudopapillary tumor of pancreas(SPT) and pancreas endocrine tumor (PET), discuss the diagnostic value of the various markers and the significance of secretagogin(SCGN) immunoreactivity in differential diagnosis. And, we wish to provide a rational approach to the immunohistochemical work-up and diagnosis of the two tumors. Finally, to investigate the ultrastractural features of the SPT and to explore its cell origin.Methods:We summarize and analyze 51 patients with SPT and 52 patients with PET who were treated at the first affiliated hospital of school of medicine, Zhejiang University from 2001 to 2010 retrospectively on clinical, imaging and pathological characteristics, therapeutic approach and prognosis were also studied. We performed immunohistochemical analysis using multiple antisera including E-ca,β-catenin, CgA, Syn, CD56 and so on, and to clarify the diagnostic usefulness of these markers in differentiating SPT from PET. We analyzed the expression of SCGN in SPT and PET by immunohistochemistry(IHC) and RT-PCR. One case of SPT was investigated by electron microscopy.Results:1. SPT may show clinical, histological and immunohistochemical overlap with PET.2. Larger tumor size, young adult, female preponderance, pseudopapillay pattern and the degenerative changes are helpful to differentiate SPT from PET.3. The immunohistochemical expression of CK-pan, Vim, PR, CD10, Gal-3, CyclinDl, CgA and Syn showed statistically difference between the two tumors but none of them is specific. A combination of various markers is useful. Diffuse positive expression of Vim, PR, CD 10, Gal-3, CyclinDl, and focal positive or negative for CK-Pan, CgA and Syn support the dignosis of SPT. While strong and diffuse staining for CK-pan, CgA and Syn support the dignosis of PET.4. Loss of membrane staining for E-ca and nuclear expression of (3-catenin is specific for SPT while PET usually shows membrane staining for E-ca and no nuclear expression ofβ-catenin.5. SCGN was negative in all SPT but was cytoplasmic and nuclear expressed in all PET and co-localized with the neuroendocrine markers CgA, Syn and CD56.6. Ultrastructrurally, the cytoplasm of SPT contained abundant mitochondria, rough endoplasm reticulum and large zymogen type granules but no neurosecretory granules.Conclusions:1. Sexuality, age with disease, tumor size and the immunohistochemical expression of CK-pan, Vim, PR, CD 10, Gal-3, CyclinDl, CgA and Syn showed statistically difference between the two tumors, but none of them is specific. A combination of various markers is useful.2. We prove that SCGN is a sensitive and specific marker for PET by immunohistochemistry and RT-PCR and it shows significant value of differential diagnosis of SPT and PET.3. A combination of various markers, including SCGN, CgA, Syn, CD56, E-ca and β-catenin could distinguish SPT and PET even in small biopsy material. Abnormal staining of E-ca andβ-catenin combined with CD56 positivity and SCGN negative can make a diagnosis of SPT, and normal staining of E-ca andβ-catenin combined with CD56 and SCGN positive can make a diagnosis of PET.4. Our immunohistochemical and ultrastructrural analysis proved the multidirectional differentiation of SPT, it may originate from a multipotenitial primordial cell, and neuroendocrine differentiation should be regarded as one of the potential lines of tumor differentiation.