Solid Pseudopapillary Tumor : Differential
Differential Diagnosis of Solid Pseudopapillary Tumor (SPT) of Pancreas: The complete differential diagnosis includes the entire spectrum of pancreatic neoplasms. Low-grade Neuroendocrine Tumor (NET): The main distinction to be made is from NET. Both SPT and NET have monomorphic cell populations. However, NET lack nuclear beta-catenin immunoreactivity and do not show the following morphologic features: hyalinized fibrovascular cores, foamy macrophages, longitudinal nuclear grooves, and eosinophilic globules. Acinar Cell Carcinoma (ACC): SPT with a predominant solid pattern may resemble ACC; however, acinar cells have prominent nucleoli and cytoplasmic zymogen granules. Trypsin and chymotrypsin are strongly positive in ACC and negative in SPT. In addition, ACC is more common in males. The image shows pseudopapillary structures with delicate branching vessels and loosely cohesive cells. Spaces between pseudopapillae may be acellular or contain red blood cells; blood lakes may be seen.