Uncommon tumors and pseudotumoral lesions of the pancreas

Pancreatic islet cell tumors in adolescents and young adults

BACKGROUND

Pancreatic islet cell tumors are rare in adolescents, and most studies published to date focus on older patients. We utilized a national database to describe the histology and clinical pattern of pancreatic islet cell tumors in adolescent and young adult (AYA) patients, and to compare AYAs to older adults. We hypothesized that AYAs with pancreatic islet cell tumors would have better overall survival.

METHODS

The National Cancer Data Base (NCDB, 1998-2012) was queried for AYA patients (15-39 years) with a pancreatic islet cell tumor diagnosis. Demographics, tumor characteristics, treatment modalities, and outcomes were abstracted and compared to adults (≥40 years).

RESULTS

383 patients (56.4% female, 65% non-Hispanic Whites) were identified, with a median age of 27 (IQR 16-34) years. Islet cell carcinoma was the most common histology. Of patients with known stage of disease, 49% presented with early stage (I or II). Seventy percent of patients underwent surgical resection, including local excision 44%, Whipple procedure 37.5%, or total pancreatectomy 19%. Chemotherapy was utilized in 27% and radiotherapy in 7%. All-cause mortality was 36%. AYA patients underwent more extensive resections (p = 0.001) and had lower mortality rates (p < 0.001), with no differences in tumor stage or use of adjuvant therapies, when compared to adults.

CONCLUSIONS

AYA patients with pancreatic islet cell tumors had comparable utilization of adjuvant therapies but underwent more extensive resections and demonstrated a higher overall survival rate than adult counterparts. Further investigation into approaches to earlier diagnosis and tailoring of multimodality therapy of these neoplasms in the AYA population is needed.

LEVELS OF EVIDENCE

Prognostic Study, Level II - retrospective study.

Mimics of pancreatic ductal adenocarcinoma

Several uncommon primary pancreatic tumors, inflammatory conditions, metastasis to the pancreas and peripancreatic masses can mimic the appearance of pancreatic ductal adenocarcinoma (PDA). Differentiation between these lesions and PDA can be challenging, due to the overlap in imaging features; however, familiarity with their typical imaging features and clinical presentation may be helpful in their differentiation, as in some cases, invasive diagnostic tests or unnecessary surgery can be avoided. The different pathologies that can mimic PDA include inflammatory conditions such as the various forms of pancreatitis (chronic-focal mass-forming, autoimmune and groove pancreatitis), pancreatic neuroendocrine tumors, solid pseudopapillary tumors, metastasis (solid non-lymphomatous and hematologic), congenital variants (annular pancreas), as well as peripancreatic lesions (accessory spleen, adrenal masses, duodenal masses, lymph nodes and vascular lesions), and certain rare pancreatic tumors (e.g., acinar cell tumors, solid serous tumors, hamartoma and solitary fibrous tumors). The clinical presentation and imaging features of the most commonly encountered mimics of PDA are discussed in this presentation with representative illustrations.

Clinical and CT imaging features of pancreatic acinar cell carcinoma

PURPOSE

This study was undertaken to analyse the clinical characteristics and computed tomography (CT) imaging features of patients with pancreatic acinar cell carcinoma and to clarify characteristic imaging features.

MATERIALS AND METHODS

Clinical and CT imaging records of ten patients with pancreatic acinar cell carcinoma (three women and seven men; mean age, 58 years) examined using multidetector CT scanners were retrospectively studied. CT features emphasised included lesion location, size, shape, margin, solid or cystic component, density and enhancement. Imaging results were correlated with intraoperative surgical and pathological results.

RESULTS

Lesions were distributed throughout the pancreatic head (n=3), body (n=3), tail (n=2) and both body and tail (n=2). The average diameter was 6.1 cm, varying from 2.3 cm to 15.8 cm. The tumours were round or oval (n=7) or lobular (n=3). Seven tumours appeared as enhanced solid pancreatic masses, with the large masses having hypodense areas; three had >75 % cystic component; seven (70%), including four solid and three cystic masses, had well-circumscribed or partially well-defined thin, enhanced encapsulation. After contrast injection, the masses presented heterogeneous enhancement.

CONCLUSIONS

Acinar cell carcinoma should always be considered when a large pancreatic mass with typical imaging is found in solid masses with variably sized central cystic areas or cystic masses.