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

Acinar cystic transformation of the pancreas: A rare case report

BACKGROUND

Acinar cystic transformation (ACT) of the pancreas is a rare non-neoplastic transformation of the pancreas. Adult women are the majority of patients with ACT, but few cases have been reported in pediatric patients. Given that there are currently no guidelines for the treatment of ACT, current treatment is based primarily on expert opinions and clinical experiences. Here, we report the case of the youngest child with ACT to date. Additionally, a literature review on pediatric ACT cases was performed to summarize previous clinical experience and treatment methods.

CASE SUMMARY

A 1-year-old Chinese girl presented with progressive abdominal distension for 6 months. A detailed consultation revealed an uneventful history. The patient showed no signs of fever or abdominal pain and had a good appetite and normal feces. A mass of about 20 cm × 10 cm × 10 cm in size was detected in the abdomen. Both abdominal ultrasound and computed tomography examination revealed a multilocular cystic mass about 21.7 cm × 16.8 cm × 8.9 cm in size. At first, due to the large size and the possible retroperitoneal origin of the cyst, a total resection of the lesion was not possible. A single-port laparoscopic lymphangioma puncture and Pingyangmycin injection were performed in March 2023. One month after surgery, the abdominal cyst rapidly enlarged to its pre-operative size. After consulting with the experts in the angiology department and interventional department, sclerotherapy combined with oral sirolimus was performed in May 2023. After confirming that the tumor was not sensitive to sclerotherapy combined with oral sirolimus, our surgical team performed tumor reduction in August 2023. This surgery confirmed that the polycystic mass originated from the head of the pancreas, and pathological and immunohistochemical findings diagnosed pancreatic ACT. The patient showed no signs of cyst lesions after 6 months of follow-up and remains in good health up to the time of this report.

CONCLUSION

ACT is a rare non-neoplastic transformation of the pancreas, more rarely seen in children. Manifestation and examinations show no specificity for diagnosis, and final diagnosis is mainly based on histological findings. To reach a specific diagnosis and rule out malignancy is a priority in clinical practice, and repeated biopsy or radical surgery should be considered before malignancy is ruled out. However, once a diagnosis of ACT is made, a conservative treatment with consecutive follow-up is recommended until symptoms present or obvious enlargement occurs because ACT is considered a slow-growing and benign tumor.

Rare pancreatic cystic neoplasms: A pictorial review

Since rare pancreatic cystic tumors may differ from common pancreatic cystic neoplasms in terms of treatment plan and prognosis, the differential diagnosis of these diseases is clinically relevant. Various imaging tests play an important role in the differential diagnosis of rare cystic pancreatic tumors, but accurately distinguishing these diseases solely on the basis of imaging findings is challenging. The purpose of this pictorial review is to present CT and in particular MR imaging features of rare pancreatic cystic tumors and discuss potential elements for differential diagnosis.

Diagnostic Pearls and Pitfalls in the Evaluation of Biopsies of the Pancreas

CONTEXT.—

The examination of small pancreatic biopsies is a difficult task for pathologists. This is due to the scant and fragmented material often obtained from diagnostic procedures as well as the significant overlap between different neoplastic and nonneoplastic entities. In the upcoming neoadjuvant era, biopsies could become even more important, representing the only possibility to look at the real histomorphology of tumors before chemotherapy-induced modifications.

OBJECTIVES.—

To summarize and discuss the state-of-the-art diagnostic workflow for small pancreatic biopsies, including the most important morphologic and immunohistochemical features and molecular alterations. The main diagnostic pearls and pitfalls of this challenging scenario are also discussed. The most important topics of this review are represented by: (1) pancreatic ductal adenocarcinoma, along with its main differential diagnoses, including autoimmune pancreatitis; (2) solid hypercellular neoplasms, including neuroendocrine neoplasms, acinar cell carcinoma, pancreatoblastoma, and solid pseudopapillary neoplasms; and (3) cystic lesions. Real-world considerations will also be presented and discussed.

DATA SOURCES.—

Sources included a literature review of published studies and the author's own work.

CONCLUSIONS.—

The correct diagnosis of pancreatic lesions is a crucial step in the therapeutic journey of patients. It should be based on robust, standardized, and reliable hallmarks. As presented and discussed here, the integration of morphology with immunohistochemistry, and, in selected cases, with molecular analysis, represents a decisive step in this complex scenario.

Reappraising imaging features of pancreatic acinar cystic transformation: be aware of differential diagnoses

OBJECTIVES

Imaging features of pancreatic acinar cystic transformation (ACT) have been published. We aimed to describe the clinical and radiological characteristics of patients with a presumed pancreatic ACT diagnosis, reappraising the value of these published imaging criteria.

MATERIALS AND METHODS

Single-center retrospective study (2003-2021) of consecutive patients with a presumed diagnosis of ACT as suggested by the local expert multidisciplinary case review board. Patients without available imaging (CT or MRI) for review were excluded. Patients were classified into "certain" ACT (if ≥ 2 imaging criteria and no differential diagnosis) or "uncertain" ACT (if ≥ 1 imaging criteria and suggested differential diagnoses).

RESULTS

Sixty-four patients (35 males, [55%]) were included. ACT was considered "certain" for 34 patients (53%) and "uncertain" for 30 patients (47%). The number of ACT criteria did not differ between groups, with 91.2% of patients with ≥ 3 ACT imaging criteria in the "certain" group vs 93.3% in the "uncertain" group (p = 0.88). In the "uncertain" group, the main suggested differentials were branch-duct intraductal papillary mucinous neoplasm (18/30 patients, 60%), calcifying chronic pancreatitis (8/30 patients, 27%), both (three patients, 10%) and serous cystadenoma (one patient, 3%). Calcifications were significantly more frequent in the "uncertain" group (89% vs 63% in the "certain" group, p = 0.02).

CONCLUSION

Published ACT imaging criteria are frequently associated with features suggesting differential diagnoses. They appear insufficient to reach a final diagnosis in a subset of patients.

CLINICAL RELEVANCE STATEMENT

ACT displays a heterogeneous morphological imaging presentation challenging the non-invasive diagnostic work-up. Physicians' and radiologists' awareness of this entity is important to better understand its natural history and improve non-invasive diagnostic criteria.

KEY POINTS

The criteria to help diagnose ACT are frequently associated with features suggestive of differentials. The main alternatives suggested when ACT diagnosis was "uncertain" were branch-duct intraductal papillary mucinous neoplasm and calcifying chronic pancreatitis. Published ACT diagnostic imaging criteria can be insufficient for a definite non-invasive diagnosis.

Acinar cystic transformation of the pancreas

Acinar cystic transformation (ACT) of the pancreas is a rare non-neoplastic cystic lesion. It is difficult to distinguish from more concerning pathology, particularly a side-branch duct intraductal papillary mucinous neoplasm (IPMN). All reported cases of ACT have been clinically benign with no evidence of recurrence or malignant transformation. The Fukuoka guidelines is a classification system designed to help guide the management of IPMNs and mucinous cystic neoplasms. We report a case of ACT that was preoperatively diagnosed as a suspected side-branch IPMN. Through the application of current guidelines, the patient underwent a Whipple's procedure. We highlight the difficulties in obtaining an accurate preoperative diagnosis in cases of ACT and the current radiological and cytological methods available to clinicians.