Fine-needle aspiration cytology of pancreatic somatostatinoma: the importance of immunohistochemistry for the cytologic diagnosis of pancreatic endocrine neoplasms

Performance of endoscopic ultrasound-guided fine needle aspiration in diagnosing pancreatic neuroendocrine tumors

Background:

Pancreatic neuroendocrine tumors (PNETs) are rare tumors of the pancreas, which are increasingly diagnosed by endoscopic ultrasound-guided fine needle aspiration (EUS-FNA). In this retrospective study, we assessed the performance of EUS-FNA in diagnosing PNETs.

Materials and Methods:

We identified 48 cases of surgically resected PNETs in which pre-operative EUS-FNA was performed. The clinical features, cytological diagnoses, and surgical follow-up were retrospectively reviewed. The diagnostic performance of EUS-FNA was analyzed as compared to the diagnosis in the follow-up. The cases with discrepancies between cytological diagnosis and surgical follow-up were analyzed and diagnostic pitfalls in discrepant cases were discussed.

Results:

The patients were 20 male and 28 female with ages ranging from 15 years to 81 years (mean 57 years). The tumors were solid and cystic in 41 and 7 cases, respectively, with sizes ranging from 0.5 cm to 11 cm (mean 2.7 cm). Based on cytomorphologic features and adjunct immunocytochemistry results, when performed, 38 patients (79%) were diagnosed with PNET, while a diagnosis of suspicious for PNET or a diagnosis of neoplasm with differential diagnosis including PNET was rendered in the 3 patients (6%). One case was diagnosed as mucinous cystic neoplasm (2%). The remaining 6 patients (13%) had non-diagnostic, negative or atypical diagnosis.

Conclusions:

Our data demonstrated that EUS-FNA has a relatively high sensitivity for diagnosing PNETs. Lack of additional materials for immunocytochemical studies could lead to a less definite diagnosis. Non-diagnostic or false negative FNA diagnosis can be seen in a limited number of cases, especially in those small sized tumors.

Pancreatic somatostatinoma with obscure inhibitory syndrome and mixed pathological pattern

Somatostatinoma is a very rare neuroendocrine tumor that originates from D cells and accounts for less than 1% of all gastrointestinal endocrine tumors. The duodenum is the most frequent site for this tumor, followed by the pancreas. We here describe a 46-year-old Chinese woman who developed pancreatic somatostatinoma presenting with the characteristic "inhibitory" syndrome, but the symptoms were obscure and seemingly uncorrelated. This case is also unique for its large tumor size and mixed pathological pattern. Distal pancreatectomy was performed, and the patient has remained well since operation. As the syndromes of somatostatinoma may be obscure and atypical, clinicians should review all clinical findings to obtain an accurate diagnosis. Aggressive surgery is preferred to improve the survival.

FNAC diagnosis of pancreatic somatostatinoma

Somatostatinomas are rare pancreatic endocrine neoplasms (PEN). We present a case of a PEN in a 63-year-old lady having diabetes mellitus, cholelithiasis, steatorrhea, weight loss, indigestion, nausea and fatigue. Ultrasonography revealed a large calcified mass occupying the liver, pancreas and emboli in the splenic vein. Fine needle aspiration cytology (FNAC) of the metastatic mass in the liver showed features of neuroendocrine tumor. Correlating the clinical picture, computed tomography and cytological findings, a diagnosis of pancreatic somatostatinoma was suggested. Serum somatostatin levels and biopsy findings confirmed the same. The patient was put on chemotherapeutic agents and octreotide and is doing well after two years of follow-up. We discuss the FNAC findings of pancreatic endocrine tumors and its differentiating features from hepatoma and other small round cell tumors.

Endoscopic ultrasound-guided fine-needle aspiration diagnosis of clear-cell pancreatic endocrine neoplasm in a patient with von Hippel-Lindau disease: a case report

The cytologic findings of a clear-cell pancreatic endocrine neoplasm (PEN) diagnosed by endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) occurring in a 29-year-old man with von Hippel-Lindau (VHL) syndrome are described. Imaging studies showed multiple pancreatic masses and cysts, a single liver lesion, and pulmonary and renal cysts. Cytologic features of this clear-cell PEN included the presence of large sheets and rounded clusters of polygonal neoplastic cells with relatively abundant cytoplasm containing numerous, small, sharply-demarcated vacuoles that occasionally indented nuclei and gave the cells a "frothy" appearance. Mild anisonucleosis was present and nucleoli were visible. Rare single cells and stripped nuclei were seen. Small vessels transgressed tumor cell sheets. These cytologic findings are distinct from those of typical endocrine neoplasms, and bear resemblance to the cytologic features of renal cell carcinoma metastatic to the pancreas. To the best of our knowledge, this is the first detailed report of the EUS-FNA cytologic findings of a clear-cell PEN associated with VHL syndrome. We believe that the distinctive and characteristic cytologic features, together with immunohistochemical studies, can allow a preoperative cytologic diagnosis of this highly unusual pancreatic lesion and avoid possible confusion with other clear-cell neoplasms in the pancreas, particularly metastatic renal cell carcinoma.

Gastrointestinal neuroendocrine tumors: pancreatic endocrine tumors

Pancreatic endocrine tumors (PETs) have long fascinated clinicians and investigators despite their relative rarity. Their clinical presentation varies depending on whether the tumor is functional or not, and also according to the specific hormonal syndrome produced. Tumors may be sporadic or inherited, but little is known about their molecular pathology, especially the sporadic forms. Chromogranin A appears to be the most useful serum marker for diagnosis, staging, and monitoring. Initially, therapy should be directed at the hormonal syndrome because this has the major initial impact on the patient's health. Most PETs are relatively indolent but ultimately malignant, except for insulinomas, which predominantly are benign. Surgery is the only modality that offers the possibility of cure, although it generally is noncurative in patients with Zollinger-Ellison syndrome or nonfunctional PETs with multiple endocrine neoplasia-type 1. Preoperative staging of disease extent is necessary to determine the likelihood of complete resection although debulking surgery often is believed to be useful in patients with unresectable tumors. Once metastatic, biotherapy is usually the first modality used because it generally is well tolerated. Systemic or regional therapies generally are reserved until symptoms occur or tumor growth is rapid. Recently, a number of newer agents, as well as receptor-directed radiotherapy, are being evaluated for patients with advanced disease. This review addresses a number of recent advances regarding the molecular pathology, diagnosis, localization, and management of PETs including discussion of peptide-receptor radionuclide therapy and other novel antitumor approaches. We conclude with a discussion of future directions and unsettled problems in the field.

Liver metastases of pancreatic acinar cell carcinoma with marked nuclear atypia and pleomorphism diagnosed by EUS FNA cytology: a case report with emphasis on FNA cytological findings

Background

Acinar cell carcinoma of the pancreas is a rare neoplasm. Although this tumor has been well characterized histologically, the morphological patterns in Fine Needle Aspiration Cytology have not been well defined. Unlike ductal adenocarcinomas, endocrine tumors, and solid pseudopapillary tumors of the pancreas with their characteristic FNA cytological features, acinar cell carcinomas pose a particular diagnostic challenge by sharing many cytomorphologic features with endocrine tumors of the pancreas.

Case presentation

A 37-year-old man presented with lower chest and left upper quadrant abdominal pain. Computed tomography revealed a 7.8 × 7.3 cm irregular, partially cystic mass in the body and tail of the pancreas, and two lesions in the liver compatible with metastases. Subsequently, the patient underwent endoscopic ultrasound-guided fine needle aspiration on one of the two metastatic liver masses.

FNA cytology revealed abundant, loosely cohesive clusters of malignant epithelial cells with vaguely acinar and trabecular formations. The pleomorphic nuclei had fine granular chromatin and occasionally small nucleoli. There were scant to moderate amounts of cytoplasm. Scattered, strikingly large tumor cells with giant nuclei, prominent mitoses and associated necrosis were evident. A pancreatic endocrine tumor was suspected initially, but acinar cell carcinoma of the pancreas was confirmed by immunohistochemistry, cytochemical and ultrastructural studies.

Conclusion

We describe a case of pancreatic acinar cell carcinoma with unusual cytomorphologic features mimicking an endocrine tumor of pancreas, encountered in endoscopic ultrasound-guided fine needle aspiration of a metastatic liver mass and discuss the diagnostic approach for this unusual pancreatic tumor in fine needle aspiration cytology.