Acinar cell cystadenoma of the pancreas: A retrospective analysis of ten-year experience from a single academic institution

Diffuse acinar cystic transformation of the pancreas: a rare case in a young male patient

We present the case of a 17-year-old male who presented with pancreatic enlargement and abdominal discomfort. Imaging showed diffusely distributed cystic lesions in the pancreas, which led to the diagnosis of a case of Acinar Cystic Transformation, a rare cystic lesion of the pancreas.

Cell of Origin of Pancreatic cancer: Novel Findings and Current Understanding

ABSTRACT

Pancreatic ductal adenocarcinoma (PDAC) stands as one of the most lethal diseases globally, boasting a grim 5-year survival prognosis. The origin cell and the molecular signaling pathways that drive PDAC progression are not entirely understood. This review comprehensively outlines the categorization of PDAC and its precursor lesions, expounds on the creation and utility of genetically engineered mouse models used in PDAC research, compiles a roster of commonly used markers for pancreatic progenitors, duct cells, and acinar cells, and briefly addresses the mechanisms involved in the progression of PDAC. We acknowledge the value of precise markers and suitable tracing tools to discern the cell of origin, as it can facilitate the creation of more effective models for PDAC exploration. These conclusions shed light on our existing understanding of foundational genetically engineered mouse models and focus on the origin and development of PDAC.

Rare Pancreatic/Peripancreatic Cystic Lesions Can Be Accurately Characterized by EUS with Through-the-Needle Biopsy-A Unique Pictorial Essay with Clinical and Histopathological Correlations

Due to their aspecific macroscopic appearance, uncommon pancreatic cystic lesions (PCLs) are often misdiagnosed as mucinous lesions and improperly resected. We aimed to evaluate the endoscopic ultrasound (EUS)-guided through-the-needle biopsy (TTNB) capacity of the preoperative diagnosis of uncommon PCLs. Overall, 136 patients with PCLs who underwent EUS-TTNB between 2016 and 2022 were retrospectively identified. Common histotypes (e.g., IPMN, serous cystadenoma, and mucinous cystadenoma) were excluded and 26 (19.1%) patients (15 female, mean age 52.9 ± 10.4) were analyzed. The EUS findings, adverse events (AEs), and TTNB outcomes in uncommon PCLs were evaluated. The cysts histotype was accurately diagnosed by TTNB in 24/26 (92.3%) cases (seven cystic neuroendocrine tumors, four squamoid cysts, three acinar cells cystadenomas, two lymphoepithelial cysts, two mucinous non-neoplastic cysts, two bronchogenic cysts, two cystic lymphangiomas, one solid-pseudopapillary neoplasm, and one schwannoma). In the remaining two cases, lymphangioma was eventually diagnosed after resection. Surgery was performed in 15/26 (57.7%) patients. The mean follow-up of non-surgical patients was 32.5 months. One severe acute case of pancreatitis (3.8%) that required surgery occurred after EUS-TTNB. Uncommon pancreatic/peripancreatic lesions represent the 19.1% of PCLs in our series, with mainly benign histotypes. TTNB demonstrated a high diagnostic performance with a low rate of AEs in this setting, representing a reliable tool with which to avoid useless surgery.

Comprehensive characterisation of acinar cystic transformation of the pancreas: a systematic review

AIMS

Acinar cystic transformation (ACT) of the pancreas is a rare pancreatic cystic lesion. Owing to its rarity, comprehensive histomolecular characterisation of this entity is still lacking. We aim to perform a systematic review on this controversial entity.

METHODS

We searched PubMed, SCOPUS and Embase through May 2023 to identify all studies on ACTs. Clinicopathological, immunohistochemical (IHC) and molecular data have been extracted and analysed.

RESULTS

Overall, there were 121 cases of ACTs in the literature. ACT had a female predominance (65.3% of patients), and a mean size of 4.8 cm. ACT was more often unifocal (71.9%) and multiloculate (61.2%). Histologically, the cysts were lined by an acinar epithelium, sometimes harbouring ductal-like areas (18.2%). In five cases (4.1%), an intralesional pancreatic intraepithelial neoplasia (PanIN) was reported. Preoperative diagnosis is challenging. After surgical resection, all patients were alive and disease free during follow-up except one patient who developed a second ACT after resection. By IHC, all lesions were positive for acinar markers; cytokeratin 7 and 8/18/19 were usually positive, and Ki-67 was invariably ≤3%. At the molecular level, three cases demonstrated genetic alterations: one showed multiple chromosomal gains, and other two harboured somatic mutations of KRAS and SMO genes (one mutation per case).

CONCLUSIONS

Globally considered, our findings demonstrated that ACT is a benign entity, without the need of surgical resection with the exception of symptomatic lesions. The rare occurrence of intracystic PanINs and driver mutations suggest considering follow-up if a preoperative diagnosis of ACT can be made.

Real-Life Management of Pancreatic Cysts: Simplified Review of Current Guidelines

Pancreatic cysts are becoming a popular diagnostic tool due to the increased availability of high-quality cross-sectional imaging. Pancreatic cystic lesions constitute closed, liquid-containing cavities, which are either neoplastic or non-neoplastic. While serous lesions often follow a benign course, mucinous lesions can hide carcinoma and, therefore, require different management. Moreover, all cysts should be considered mucinous until proven otherwise, thus limiting the errors in managing these entities. Due to the need for high contrast soft tissue imaging, magnetic resonance imaging represents an elective, non-invasive diagnostic tool. Endoscopic ultrasound (EUS) has started gaining more prominence with regard to the proper diagnosis and management of pancreatic cysts, offering quality information with minimal risks. Enabling both the acquisition of endoscopic images of the papilla and the endosonographic high-quality evaluation of septae, mural nodules along with the vascular patterns of the lesion contribute to a definitive diagnosis. Moreover, the possibility of obtaining cytological or histological samples could become mandatory in the foreseeable future, allowing for more precise molecular testing. Future research should focus on detecting methods to quickly diagnose high-grade dysplasia or early cancer for patients with pancreatic cysts, thus allowing time for appropriate treatment and avoiding surgical overtreatment or over surveillance in selected cases.

Acinar Cystic Transformation of the Pancreas: Histomorphology and Molecular Analysis to Unravel its Heterogeneous Nature

Acinar cystic transformation (ACT) of the pancreas, previously called acinar cell cystadenoma, is a poorly understood and rare entity among pancreatic cystic lesions. This study aims to clarify its real nature. This research cohort included 25 patients with pancreatic ACT, representing the largest series in the literature. We describe their clinicopathological features and molecular profile using next-generation sequencing. ACT arose more often in women (F/M≃2:1), in the body-tail region, with a mean size of ~4 cm. At the latest follow-up, all patients were alive and disease free. Histologically, a typical acinar epithelium lined all cysts, intermingled with ductal-like epithelium in 11/25 (44%) cases. All the cases lacked any evidence of malignancy. Three ACT showed peculiar features: 1 showed an extensive and diffuse microcystic pattern, and the other 2 harbored foci of low-grade pancreatic intraepithelial neoplasia (PanIN) in the ductal-like epithelium. Next-generation sequencing revealed the presence of 2 pathogenic/likely pathogenic mutations in 2 different cases, 1 with ductal-like epithelium and 1 with PanIN, and affecting KRAS (c.34G>C, p.G12R) and SMO (c.1685G>A, p.R562Q) genes, respectively. The other case with PanIN was not available for sequencing. Overall, our findings support that ACT is a benign entity, potentially arising from heterogeneous conditions/background, including: (1) acinar microcysts, (2) malformations, (3) obstructive/inflammatory setting, (4) genetic predisposition, (5) possible neoplastic origin. Although all indications are that ACT is benign, the potential occurrence of driver mutations suggests discussing a potential role of long-term surveillance for these patients.

Acinar Cystic Transformation of the Pancreas: Report of Three Cases

Acinar cystic transformation (ACT) of the pancreas is a rare non-neoplastic cystic lesion. It is most frequently observed in the head of the pancreas. Despite advances in radiologic imaging methods, preoperative diagnosis of acinar cystic transformation is difficult, it is often confused with other cystic lesions. Here, we report three cases of acinar cystic transformation, one of which showed diffuse involvement of the pancreas, and the remaining two were multilocular localized cystic lesions. We analyzed their histomorphologic and immunohistochemical features. The patients' ages ranged between 15 and 43 years and the ratio of females to males was 2:1. On microscopic examination, the cysts were lined by a single layer of flattened-cuboidal or columnar epithelial cells. The epithelial cells were diffusely positive with trypsin and keratin 7, but patchy with keratin 19. Due to its rarity and lack of radiologic and clinical awareness compared with other pancreatic cystic lesions, preoperative diagnosis of acinar cystic transformation is difficult and not definitive. All cases reported to date have been clinically benign and there is no evidence of recurrence or malignant transformation. The optimal treatment and whether to perform surgery remain controversial.

Pancreatic Acinar Cell Cystadenoma Mimicking Pancreatic Serous Cystadenoma

Acinar cell cystadenoma, also known as an acinar cystic transformation of the pancreas, is an exceedingly rare but benign pancreatic lesion. A 51-year-old woman was transferred to Inje University Busan Paik Hospital because of an 8 cm-sized calcified, multiseptated, and multilocular cystic mass in the pancreatic tail observed during abdominal CT performed at another hospital. The patient did not complain of abdominal pain or other symptoms, and her laboratory findings were normal. MRI showed that the cyst was not connected to the main pancreatic duct. A pancreatic serous cystadenoma was suspected, and a laparoscopic distal pancreatectomy was performed. The resected mass was composed of variable sized multilocular cysts with incomplete septa and focally lined by epithelium with acinar differentiation. The patient was diagnosed with acinar cell cystadenoma and is currently being followed up regularly. No complications or recurrences have been observed.

Cystic pancreatic lesions: MR imaging findings and management

Cystic pancreatic lesions (CPLs) are frequently casual findings in radiological examinations performed for other reasons in patients with unrelated symptoms. As they require different management according to their histological nature, differential diagnosis is essential. Radiologist plays a key role in the diagnosis and management of these lesions as imaging is able to correctly characterize most of them and thus address to a correct management. The first step for a correct characterization is to look for a communication between the CPLs and the main pancreatic duct, and then, it is essential to evaluate the morphology of the lesions. Age, sex and a history of previous pancreatic pathologies are important information to be used in the differential diagnosis. As some CPLs with different pathologic backgrounds can show the same morphological findings, differential diagnosis can be difficult, and thus, the final diagnosis can require other techniques, such as endoscopic ultrasound, endoscopic ultrasound-fine needle aspiration and endoscopic ultrasound-through the needle biopsy, and multidisciplinary management is important for a correct management.

Fifteen-Year Follow-Up of a Patient with Acinar Cystic Transformation of the Pancreas and Literature Review

Acinar cystic transformation (ACT), also known as “acinar cell cystadenoma,” is a rare and newly recognized benign pancreatic cystic neoplasm. However, its true malignant potential remains unknown. Here, we report a case of ACT with 15-year follow-up. A 10-year-old female initially presented with abdominal pain and was found to have a cystic lesion in the region of pancreatic head on computed tomography scan. She underwent an exploratory laparotomy, and the intraoperative biopsy of the cyst wall showed a true pancreatic cyst without malignancy. Her symptoms subsequently resolved, and she was placed under close ultrasound surveillance. For the next fifteen years, the patient was asymptomatic without any complications and had a successful pregnancy. Surveillance showed the tumor grew in size from 4.2 cm to 6.2 cm in diameter. In the latest five months, she noted occasional abdominal pain. A pylorus-preserving pancreaticoduodenectomy was performed. The resected cystic lesion was multilocular and lined by a single layer of bland epithelium ranging from nondescript flat/cuboidal epithelium to apparent acinar cells which were strongly positive for trypsin, so the final diagnosis was confirmed to be ACT. The prior biopsy was retrospectively reviewed to reveal similar epithelial lining. To the best of our knowledge, this is the longest period of follow-up for ACT to date. Our findings suggest that ACT is a slow-growing neoplasm without malignant transformation after fifteen years. Therefore, we recommend biopsy for histologic diagnosis followed by close ultrasound surveillance without surgical intervention in asymptomatic or young ACT patients.

Acinar cystic transformation of the pancreas: Report of a case and a review of the literature

Acinar cystic transformation (ACT) is a rare cystic lesion of the pancreas lately reclassified as a non-neoplastic entity. This is a presentation of a case of ACT and a review of the literature. A systematic PubMed search was conducted, yielding a result of 24 publications. Including our case report, 75 cases of ACT have been reported in the literature. The patients are mainly females with initial symptoms of abdominal pain. The cysts are primarily located in the head of the pancreas and are often multilocular on cross section and have a mean size of 53.2 mm. Microscopically, the cysts are lined by an acinar epithelium with abortive acinar formations. The cells are immunohistochemically positive in stains for trypsin, chymotrypsin and CK7. The Ki67-index is low; 1-2 %. No genetic alterations indicative of a neoplastic pathogenesis have been found. The mean follow up time is 37.4 months and no malignant transformation has been observed. A preoperative diagnosis is difficult to establish, but microbiopsies seem a promising tool. The indication for surgical intervention should be founded on the symptoms of the patients since no malignant transformation has ever been reported.

The Unusual Suspects of the Pancreas-Understanding Pancreatic Acinar Cell Carcinomas and Adenomas

PURPOSE

Acinar cell carcinomas (ACC) and adenomas (ACA) of the pancreas are rare entities. Sufficient knowledge about occurrence and prognosis is scarce.

METHODS

A retrospective chart review of our database was performed for all patients who had undergone pancreatic surgery between 2006 and 2018. Results were compared to recent literature findings.

RESULTS

Nine patients were diagnosed with ACC and four patients with ACA of the pancreas in the study period. ACC patients were older and more often male than patients of the ACA group. ACC were mainly localized in the pancreatic head, whereas ACA were more often found in the distal pancreas. Tumor markers are not necessarily elevated, even in case of malignancy.

CONCLUSIONS

ACC and ACA are very rare pancreatic tumors. Both entities account for less than 1% of all pancreatic neoplasms. Diagnosis is challenging due to unspecific radiologic features and clinical symptoms. Nevertheless, a patient complaining of abdominal discomfort and an unclear hypodense pancreatic lesion should undergo surgical exploration.

Post-obstructive cyst formation in pancreas and cystic acinar transformation: Are they same?

Pancreatic "acinar cell cystadenoma" (PACA) is a rare benign pancreatic cystic lesion showing acinar cell differentiation. The neoplastic nature of PACA has been questioned and its exact pathogenesis remains unclear. To investigate that acinar cell differentiation is a non-specific metaplastic phenomenon that can occur in pancreatic ductal system, especially when chronically inflamed and dilated, and doesn't necessarily imply an acinar cell neoplasm, we retrospectively analyzed cases diagnosed as PACA and cases with post-obstructive cystic dilatation of pancreatic ducts for acinar cell differentiation using immunohistochemistry for trypsin. The etiology of obstruction was microscopic periductal pancreatic neuroendocrine tumors (PanNET) and pancreatic ductal adenocarcinomas (PDAC). All cases of post-obstructive cystic dilatation showed multiple varying sized cysts distal to the obstruction with histologic findings virtually identical to PACAs. The cysts in both conditions were lined by a single layer of non-dysplastic flattened to columnar ductal-type epithelium with areas of acinar cell differentiation. Trypsin immunohistochemistry confirmed presence of acinar cell differentiation in all cases of post-obstructive cysts and PACAs. Our results suggest that acinar cell differentiation is common in post-obstructive cyst formation, and changes are identical to PACAs. These findings further support the notion that PACA is a benign non-neoplastic cystic lesion with acinar cell differentiation. The findings also suggest that in cases with histology resembling "PACA" or showing diffuse ductal cystic dilation, careful gross examination should be carried out for a proximal obstructive lesion, which can be subtle and easily be missed on initial examination.