Abdominal pain is the predominant and, sometimes, the only symptom present. The pain may be associated with a palpable abdominal mass, anorexia, or weight loss, but any of these signs may occur in isolation. The appearance of an abdominal mass is not considered to be a symptom. Rather, these patients usually complain of a full sensation and abdominal discomfort, and only on examination can a mass be appreciated, especially in the left upper quadrant. The simultaneous presence of pain and an abdominal mass does not suffice to confirm the pancreatic origin of the lesion.

The non-specific clinical features and the young mean age at the time of presentation are frequent reasons for the tendency to underestimate this tumor, by patients and doctors. For the latter, it could be useful to divide these patients based on the anatomical location of the lesion. In our experience, abdominal pain is more often present when the tumor is located in the bodytail of the pancreas, and in some cases is related to weight loss and abdominal discomfort, when a mean tumor diameter of 8.8 cm is reached. Fewer symptoms occur with tumors with a mean diameter of 5.4 cm and located in the head of the pancreas; in such cases, jaundice is seen in 4% of patients and gastrointestinal discomfort in 8%. Thus, it can be assumed that symptoms, in particular abdominal pain, are related to the size and behavior of the tumor, which involves near-by structures. This is different from the abdominal pain associated with ductal carcinoma of the pancreas, which is due to retroperitoneal nerve infiltration. The difference between the sizes and symptoms of SPNs are probably due to their slow evolution and low grade of malignancy.

Laboratory data are not significant in these tumors due to the lack of a specific tumor marker. Chromogranin A, which has a higher sensitivity for endocrine tumors (68%), could be useful in the differential diagnosis between non-functioning endocrine neoplasms and SPNs [12], although the literature reports a positive result in the absence of an endocrine tumor in 19% of cases [13]. In our experience, the chromogranin A test was always negative in SPNs.

Solid papillary neoplasms are well-vascularized and encapsulated masses with definite margins [14] (Fig. 4.3). Calcifications and septa may be seen inside the mass but they are not pathognomonic. Instead, the distinctive findings of these tumors are the alternation of solid and cystic areas, in which a necrotic hemorrhagic component may be present [15] (Fig. 4.4a, b). These findings may be seen in the same lesion, possibly with differences in the proportions of the two components.

The lesions are sometimes reported as cystic even though the finding of a rich vascularization could lead to their being mistaken for neuroendocrine tumors.

Surgical treatment must be considered in all the patients diagnosed with SPNs, based on the still unknown biological behavior and potential malignancy of these tumors. The laparoscopic approach has been shown to be safe and feasible, if expertise is available; the median follow-up is 47 months (range 5–98). Care must be taken during surgery to prevent specimen rupture [16]. Metastatic disease is not considered a contraindication to surgery, as survival after the resection of liver metastases exceeds 5 years (range 6 months to 17 years). Recurrences are seen mainly in malignant SPNs but the long-term survival of these patients has been reported if they are treated [17–19].