Solid and Papillary Neoplasm and Nonfunctioning Islet Cell Tumor: Differential Diagnosis and Study of Histopathogenesis by Immunohistochemical Staining

ABSTRACT

PURPOSE: Solid and papillary neoplasms and nonfunctioning islet cell tumors are both rare pancreatic tumors, and their clinical and pathological features are similar which makes it hard to differentiate between them. Because both tumors have different prognoses, it is important to have precise diagnosis. The etiology of solid and papillary neoplasm is not precisely known. The role of sexual hormone has been debated as this tumor occurs mostly in women. METHODS: We retrospectively reviewed the medical records of 13 patients with solid and papillary neoplasm and 11 patients with nonfunctioning islet cell tumors who had been treated by surgical resection between October 1994 and May 1999 at Samsung Medical Center. Immunohistochemical stainings were performed for neuron-specific enolase (NSE), chromogranin, somatostatin, alpha 1-antitrypsin, estrogen (ER), and progesterone (PR) receptors. RESULTS: The average ages of the patients with solid and papillary neoplasms and nonfunctioning islet cell tumors were 39.5 and 47.8 respectively. The male to female ratio was 2 to 11 and 6 to 5, respectively and solid and papillary neoplasms were more common in women. CT showed a cystic mass in 76.9% (10/13) of the solid and papillary neoplasm patients and 20% (2/10) of nonfunctioning islet cell tumor patients. Lymphadenopathy was noted in 0% (0/13) of the solid and papillary neoplasm cases and in 50% (5/10) of the nonfunctioning islet cell tumor cases, and calcifications were present in 46.2% (6/13) and 0% (0/10) of those cases, respectively. The solid and papillary neoplasms were located most commonly inthe tail of the pancreas (7 cases), and nonfunctioning islet cell tumors were located most commonly in the head of the pancreas (5 cases). No malignancies were detected in the solid and papillary neoplasms. Seven cases of the nonfunctioning islet cell tumors (63.6%) were malignant. Both solid and papillary neoplasms and nonfunctioning islet cell tumors stained positive for NSE and alpha 1-antitrypsin in all cases and they were chromogranin positive in 25% (3/12) and 100% (10/10) and somatostatin positive in 25% (3/12) and 60% (6/10) of the cases, respectively. A solid and papillary neoplasm stained positive for ER in 1 case and for PR in 5 cases. However, only 1 case of a nonfunctioning islet cell tumor stained positive for PR. CONCLUSION: A nonfunctioning islet cell tumor is more malignant tumor than a solid and papillary neoplasm, and age, presence of cysts, lymphadenopathy, calcification, and chromogranin staining can all be used for differential diagnoses of these tumors. Both the solid and papillary neoplasms and the nonfunctioning tumors are thought to originate from a stem cell capable of differentiating into endocrine cells. The sexual hormone seems to have a role in the development of solid and papillary neoplasms.