Acinar Cell Carcinoma with Morphological Change in One Month

A case of pancreatic acinar cell carcinoma implantation in multiple branches of the pancreatic duct without main tumor continuity: a rare case report

Background

Pancreatic acinar cell carcinoma (PACC) is a rare subtype of pancreatic cancer and the clinicopathological behavior of PACC is not yet fully understood. PACC rarely invades the main pancreatic duct (MPD), which causes intraductal growth. Thus, herein, we have reported a rare case of PACC that invaded the MPD and disseminated to the branches of the pancreatic duct (BDs) without exhibiting any continuity with the main tumor.

Case Description

A 60-year-old man was found to have a hypo echoic pancreatic head mass on abdominal ultrasonography during a routine medical checkup. In computed tomography, a 30-mm hypo-dense mass was found in the pancreas head. An endoscopic retrograde pancreatography was performed to collect pancreatic juice for cytological examination. MPD was narrowing in pancreatic head and caudal MPD was slightly dilated. Although no malignant cells were detected, a pancreaticoduodenectomy was performed. Histological examination of the excised specimen confirmed the diagnosis of PACC with MPD invasion. Furthermore, tumor implantation was detected in multiple BDs that were downstream of the main tumor, without any continuity with the main tumor.

Conclusions

PACC can metastasize and get implanted in multiple BDs. Thus, post-surgical relapse can occur due to metastatic lesions implanted in the remnant pancreas.

Comprehensive review of pancreatic acinar cell carcinoma: epidemiology, diagnosis, molecular features and treatment

Pancreatic acinar cell carcinoma is a rare form (0.2-4.3%) of pancreatic neoplasm with unique clinical and molecular characteristics, which largely differ from pancreatic ductal adenocarcinoma. Pancreatic acinar cell carcinoma occurs more frequently in males and can occur in children. Serum lipase is elevated in 24-58% of patients with pancreatic acinar cell carcinoma. Pancreatic acinar cell carcinomas tend to be large at diagnosis (median tumour size: ~5 cm) and are frequently located in the pancreas head. Radiologically, pancreatic acinar cell carcinoma generally exhibits a solid appearance; however, necrosis, cystic changes and intratumoral haemorrhage can occur in larger lesions. Immunostaining is essential for the definitive diagnosis of pancreatic acinar cell carcinoma. Compared with pancreatic ductal adenocarcinoma, pancreatic acinar cell carcinoma has a more favourable prognosis. Although radical surgery is recommended for patients with pancreatic acinar cell carcinoma who do not have distant metastases, the recurrence rate is high. The effectiveness of adjuvant therapy for pancreatic acinar cell carcinoma is unclear. The response to FOLFIRINOX is generally favourable, and some patients achieve a complete response. Pancreatic acinar cell carcinoma has a different genomic profile compared with pancreatic ductal adenocarcinoma. Although genomic analyses have shown that pancreatic acinar cell carcinoma rarely has KRAS, TP53 and CDKN2A mutations, it has a higher prevalence of homologous recombination-related genes, including BRCA1/2 and ATM, than pancreatic ductal adenocarcinoma, suggesting high sensitivity to platinum-containing regimens and PARP inhibitors. Targeted therapies for genomic alternations are beneficial. Therefore, genetic testing is important for patients with pancreatic acinar cell carcinoma to choose the optimal therapeutic strategy.

Rare Non-Neuroendocrine Pancreatic Tumours

The most common tumour of the pancreas is ductal adenocarcinoma (PDAC). It remains one of the most lethal non-neuroendocrine solid tumours despite the use of a multi-approach strategy. Other, less-common neoplasms, which are responsible for 15% of pancreatic lesions, differ in treatment and prognosis. Due to the low incidence rate, there is a lack of information about the rarest pancreatic tumours. In this review, we described six rare pancreatic tumours: intraductal papillary mucinous neoplasm (IPMN), mucinous cystadenoma (MCN), serous cystic neoplasm (SCN), acinar cell carcinoma (ACC), solid pseudopapillary neoplasm (SPN) and pancreatoblastoma (PB). We distinguished their epidemiology, clinical and gross features, covered the newest reports about courses of treatment and systematised differential diagnoses. Although the most common pancreatic tumour, PDAC, has the highest malignant potential, it is still essential to properly classify and differentiate less-common lesions. It is vital to continue the search for new biomarkers, genetic mutations and the development of more specific biochemical tests for determining malignancy in rare pancreatic neoplasms.

Pancreatic mixed acinar-neuroendocrine carcinoma in a patient with a germline BRCA2 mutation: a case report

Loss of function in the BRCA2 gene exacerbates ovarian, breast, and pancreatic ductal cancer risk. Despite being implicated in the pancreatic ductal epithelium carcinogenesis, the involvement of a germline BRCA2 mutation in acinar and endocrine cells is less reported. A 45-year-old woman with a history of breast cancer was referred to our hospital for a detailed examination of epigastric pain. Her father had pancreatic cancer, and her paternal aunt had a history of breast cancer. Contrast-enhanced computed tomography revealed a round tumor with a contrast effect in the pancreatic head. The patient underwent pancreaticoduodenectomy, and postoperative pathology and genetic testing revealed amphicrine-type mixed acinar-neuroendocrine carcinoma with a germline BRCA2 mutation. Recent studies have reported the BRCA2 mutation in genome sequencing of pancreatic acinar cell carcinoma and neuroendocrine tumor; perhaps, genetic testing for the BRCA2 mutation is feasible for patients with mixed neuroendocrine-non-neuroendocrine neoplasm.