Original ArticleContrast-enhanced multiphasic CT and MRI findings of adenosquamous carcinoma of the pancreas
Introduction
Adenosquamous carcinoma of the pancreas (PASC) is a rare histological subtype of pancreatic adenocarcinoma, which comprises only l%–4% of exocrine pancreatic malignancies [1], [2], [3], [4]. Histologically, PASC is distinguished from ductal adenocarcinoma of the pancreas (PDAC) by the presence of 30% or more malignant squamous cells [1], [2]. Clinically, the prognosis of this rare tumor is less favorable than PDAC, with few patients surviving more than 1 year after surgical resection [3]. Adjuvant chemoradiation may markedly improve survival rates of PASC as shown by others [2]. Therefore, preoperative diagnosis of PASC may be important for optimal therapeutic planning.
PASC is recognized as a distinct clinic pathological entity. However, to the best of our knowledge, a comprehensive analysis of PASC by computed tomography (CT) and magnetic resonance imaging (MRI) has not been previously reported. Some case reports have described CT features of PASC as large infiltrative pancreatic tumors with central necrosis [5], [6]. However, for this cohort, the size of this central necrosis relative to the overall size of the tumor seen in PASC was relatively large. In addition, MRI findings of this rare tumor have not been previously reported in the literature. Therefore, the objective of this study was to describe both CT and MRI findings in PASC.
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Patients
The current study was a retrospective analysis, which was approved by the institutional review boards of two hospitals, wherein the requirements for informed consent were also waived. We reviewed the surgery, pathology records, and radiologic studies of two premier hospitals in China over a 12-year period (2000–2012) and identified 25 patients with pathologically proven PASCs. The picture archiving and communication system was well established in our hospital and had been applied since 2009. We
CT findings
CT findings of PASC are summarized in Table 1. PASC presented with a mean dimension of 3.7×2.9 cm (with a range of 2.4×2.0 cm to 5.5×4.1 cm). PASC was found to be located in the pancreatic head (n= 6), tail (n= 5), and body (n= 1). In addition, 83.3% (10/12) of the patients presented with tumors larger than 3 cm. Tumors were ill defined in eight (8/12, 66.7%) cases and well defined in the remaining four cases (4/12, 33.3%; Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5). The shape of the PASC was found to
Discussion
To our knowledge, comprehensive reports describing CT and MRI features of PASC are not currently available. The imaging features of PASC illustrated in previously published case reports have been variable [5], [6], [8], [9], [10]. The aim of the current study was to describe the imaging features of a series of pathologically proven PASC cases. PASC is also variously referred to as adenoacanthoma, mixed squamous and adenocarcinoma, and mucoepidermoid carcinoma and accounts for 1%–4% of exocrine
Conclusion
We found that PASC typically presented as an ill-defined, hypovascular mass with PEA, exophytic tendency, and peripancreatic tissue invasion by either CT or MRI. Lack of pancreatic atrophy and mild pancreatic duct dilatation were also distinct from those seen in PDAC. Further research with larger cases is clearly needed for this rare type of pancreatic carcinoma.
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