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CASE REPORT |
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| Acinar cystic transformation of the pancreatic body and tail in an elderly male patient: A case report |
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Anubhav Narwal1, Rajesh Panwar2, Kumble S Madhusudhan3, Sujoy Pal2, Prasenjit Das1
1 Department of Pathology, All India Institute of Medical Sciences, New Delhi, India
2 Department of Gastrointestinal Surgery, All India Institute of Medical Sciences, New Delhi, India
3 Department of Radiology, All India Institute of Medical Sciences, New Delhi, India
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| Date of Submission | 29-Dec-2021 |
| Date of Decision | 08-Dec-2022 |
| Date of Acceptance | 10-Dec-2022 |
| Date of Web Publication | 03-Feb-2023 |
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 Abstract | | |
Acinar cystic transformation (ACT) is a rare benign cystic lesion of the pancreas reported in elderly women. ACT can be easily confused with other cystic lesions of the pancreas, such as intraductal papillary neoplasm and serous and mucinous neoplasms, on imaging, especially when detected radiologically in a male patient as the index case. A preoperative histological examination can establish a diagnosis and avoid extensive surgical resection. We hereby report a case of ACT in a 69-year-old male patient that affected the body and tail region of the pancreas.
Keywords: Acinar, cyst, male, neoplasm, pancreas, transformation, trypsin
How to cite this URL:
Narwal A, Panwar R, Madhusudhan KS, Pal S, Das P. Acinar cystic transformation of the pancreatic body and tail in an elderly male patient: A case report. Indian J Pathol Microbiol [Epub ahead of print] [cited 2023 Dec 1]. Available from: https://www.ijpmonline.org/preprintarticle.asp?id=369083 |
| Introduction | |  |
Acinar cystic transformation (ACT) is an extremely rare benign cystic lesion of the pancreas, first described in 2002 as an acinar cystadenoma,[1] and included in the WHO classification of tumors in 2010. In the 2019 WHO classification of tumors, this entity was named ACT and categorized under non-neoplastic cystic lesions. Seventy-six cases have been reported in the literature, the majority in females [54/76 (71%)] with a mean follow-up of 37.4 months, occurring in all parts of the pancreas, while half of the cases are in the pancreatic head.[2],[3] The main issue in diagnosis is its similarity to other cystic pancreatic tumors, and preoperative diagnosis is elusive.[2],[3] We describe a case of ACT in a 69-year-old man highlighting its extreme rarity to occur at this age and the absence of classical radiological findings to differentiate it from other cystic pancreatic lesions.
| Case Report | | |
A 69-year-old male, known hypertensive and having hypothyroidism, developed abdominal distension and bloating over the last five years. He had no history of weight loss, appetite, jaundice, melena, or hematemesis. The general physical and abdominal examination was unremarkable. An ultrasound abdomen showed a cystic lesion in the body and tail of the pancreas, which on magnetic resonance imaging, appeared as a large multi-septate cystic mass with enhanced internal septations without mural nodules or calcifications [Figure 1]. The main pancreatic duct was compressed and dilated in the distal body and pancreatic tail, while the proximal pancreatic duct was normal [Figure 1]. A clinic-radiological diagnosis of mucinous neoplasm of the pancreas was made, and intraoperatively, a 5 × 4 cm cystic mass was identified in the distal body of the pancreas, abutting and compressing the splenic vessels; hence, a distal pancreatosplenectomy was performed. | Figure 1: (a) Axial T2-weighted and (b) contrast-enhanced T1-weighted. MR images show a multiseptated cystic lesion (arrows) in the body and tail of the pancreas (asterisk) showing septal and peripheral enhancement (b)
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The sample measured 14.5 × 9 × 4 cm, comprising the distal pancreas measuring 10 × 5.5 × 3 cm and the spleen measuring 9 × 6.8 × 4 cm and weighing 121.6 g. In serial sectioning, multiple communicating thin-walled cysts involving the body and tail of the pancreas, situated 2 cm from the pancreatic resected margin, measuring 3.5 × 3 × 2 cm [Figure 2]a. The spleen was unremarkable. Microscopic examination revealed variably sized cysts lined by low columnar to cuboidal cells with moderate granular eosinophilic cytoplasm and focal mucinous metaplasia. The nuclei in these cells were located basally, with focal nuclear pseudo-stratification [Figure 2]b, [Figure 2]c, [Figure 2]d. In the wall, interconnected groups of pancreatic acini were identified. Minute foci of calcification and residual islets of Langerhans were noted in the cyst wall with extensive fibrosis and mild chronic inflammatory cell infiltrate. The cyst-lining epithelium was positive for CK7 and trypsin while negative for CK20, CDX2, and chromogranin. Ki-67 labeling index was <1% [Figure 2]e, [Figure 2]f, [Figure 2]g, [Figure 2]h. Hence, the diagnosis of ACT of the pancreas was made. Eleven lymph nodes were isolated, which on microscopy, showed features of reactive follicular hyperplasia, free of tumor. The resected margin shows normal pancreatic parenchyma. Sections examined from the spleen showed subcapsular and red pulp congestion. | Figure 2: A gross photomicrograph of the central pancreatectomy specimen shows multiple thin-walled cysts (a, arrows). Microscopic examination showed thick fibrous cyst walls lined by a layer of low columnar epithelium showing eosinophilic granular cytoplasm (b × 40, c × 100, d × 200, arrows). These epithelial cells are positive for CK7 (e × 100, arrow) and trypsin stains (g × 400, arrows), while negative for chromogranin staining (f × 200). Ki67 labeling index was low (h × 200)
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The postoperative course was uneventful, and the patient was discharged on the 7th postoperative day. The patient was recovering well and was asymptomatic at six weeks of follow-up.
| Discussion | | |
Here, we report a case of multicystic ACT involving the pancreatic body and tail in an elderly male patient, which was preoperatively suspected to be a mucinous cystic neoplasm because of its multicystic appearance. Pancreatic cystic lesions can be broadly grouped into pseudocyst, cystic degeneration of the solid neoplasms like solid pseudopapillary neoplasm, cystic adenocarcinoma, rarely cystic neuroendocrine tumors, or serous cystadenoma and mucinous cystadenomas.[4] Among these, all can be multi-cystic, though mucinous cystadenoma and cystic degeneration of malignancies can be unicystic. Serous cystadenoma characteristically shows multiple smaller cysts lined by flat to low cuboidal cells with a central fibrous scar, closely mimicking the histology of an ACT. However, the cyst lining epithelium differs in these two types of cysts. While the cyst lining epithelium in ACT shows zymogen granules and positivity for trypsin, chymotrypsin, or pancreatic lipase, the cyst lining in serous cystadenoma does not show the zymogen granules and is negative for trypsin stain. In the index case, zymogen granules were noted in the cyst lining epithelium with positivity for trypsin stain [Figure 2]. In both serous cystadenoma and ACT, no communication with the pancreatic duct is noted. Central fibrous scar, like that in a serous cystadenoma, is also not usually seen in ACT [Figure 1]. Though focal mucinous metaplasia can be seen in the cyst lining epithelium in an ACT, unlike the main duct or branch duct, IPMNs communication is not seen with the main duct or branch ducts, respectively. Like the main duct IPMN, the ovarian-like stroma is not seen below the cyst lining epithelium in the ACT.[5] Mural nodule, like in pancreatic SPEN, is also not common in the ACT.[6],[7],[8]
Till the early 2000s, all acinar neoplasm of the pancreas was considered malignant until 2002, when the term acinar cystadenoma was coined.[1] Most of them show a female preponderance (71%) with a mean age of presentation at 44.8 years, with abdominal pain as the main presenting symptom. ACT is distinctively uncommon in elderly male patients. Of the reported cases, 27 cases were reported in the pancreatic body or tail.[2] No specific diagnostic feature has been reported on imaging, including any specific pattern of calcification or communication with the pancreatic duct. Therefore, a confirmatory diagnosis can be established only on histological examination showing typical low cuboidal granular cytoplasm of the cyst lining epithelium, highlighted by CK7 and trypsin stains. Focally mucinous metaplasia of cyst lining can be seen, though rarely they are highlighted by CK20 stain. The presence of pancreatic acini in the cyst wall is a histological hallmark of this type of pancreatic cystic lesion. IHC stains in SPEN are characteristically positive for CD10, PR, and beta-catenin stains and negative for chromogranin stains. Chromogranin can highlight a cystic neuroendocrine tumor, another example of a cystic pancreatic tumor. There are no available reports of recurrence and metastasis in pancreatic ACT, as in the index case, regardless of the partial or total resection of the lesions.[2],[5] Rarely, an ACT can be complicated by coexisting pancreatic neuroendocrine tumors or IPMN.[2] In extreme cases, primary retroperitoneal ACT arising from ectopic pancreatic tissue or cystic transformation of pancreatic acini in a teratoma has been reported.[7]
The pathogenesis of ACT remains unclear. Multiple chromosomal gains involving 1p, 3p, 5q, 6p, 7q, 8, 10q, 11, 14, 20, and X in multi-cystic ACT with mural nodules have been reported, suggesting its neoplastic nature.[8] In contrast, others have shown random inactivation and lack of mutations in the KRAS, SMAD4, TP53, and beta-catenin genes without mural nodules.[9],[10] These suggest that ACT without mural nodule could be non-neoplastic dilation of the acinar and ductal epithelium. Though surgical resection seems sufficient,[3] considering the rarity of this lesion, the true malignant potential of this entity has not yet been established.
| Conclusion | | |
Most of the ACT has been reported in middle-aged to elderly women involving the pancreatic head. Our case is unique as it occurred in the pancreatic body/tail region in an elderly male patient, causing preoperative diagnostic difficulty and histological examination proved diagnostic. Although rare, ACT should be included in the differential diagnoses of cystic pancreatic neoplasms, especially of serous cystadenomas of the pancreas. A careful histological examination of pancreatic cystic neoplasms may prevent complications related to radical surgical procedures and establish the true nature of the lesion.
Authors' contributions
AN and PD made the histological workup and wrote the manuscript. RN and SP were responsible for the patient management and surgical procedure performed on this patient. KSM performed the radiological analyses. RP and KSM provided critical input in manuscript preparation. PD is the overall guarantor of this article.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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| 8. | Khor TS, Badizadegan K, Ferrone C, Fernández-del Castillo C, Desai GS, et al. Acinar cystadenoma of the pancreas: A clinicopathologic study of 10 cases including multilocular lesions with mural nodules. Am J Surg Pathol 2012;36:1579-91. |
| 9. | Singhi AD, Norwood S, Liu TC, Sharma R, Wolfgang CL, Schulick RD, et al. Acinar cell cystadenoma of the pancreas: A benign neoplasm or non-neoplastic ballooning of acinar and ductal epithelium? Am J Surg Pathol 2013;37:1329-35. |
| 10. | Bergmann F, Aulmann S, Welsch T, Herpel E, Werner J, Schirmacher P, et al. Molecular analysis of pancreatic acinar cell cystadenomas: Evidence of a nonneoplastic nature. Oncol Lett 2014;8:852-8. |
Correspondence Address:
Prasenjit Das,
Department of Pathology, All India Institute of Medical Sciences, New Delhi - 110 029
India
 Source of Support: None, Conflict of Interest: None DOI: 10.4103/ijpm.ijpm_1263_21
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