Elsevier

Clinical Imaging

Volume 37, Issue 6, November–December 2013, Pages 1054-1060
Clinical Imaging

Original Article
Contrast-enhanced multiphasic CT and MRI findings of adenosquamous carcinoma of the pancreas

https://doi.org/10.1016/j.clinimag.2013.08.002Get rights and content

Abstract

Objective

The objective was to retrospectively study computed tomography (CT) and magnetic resonance imaging (MRI) findings of adenosquamous carcinoma of the pancreas (PASC).

Materials and Methods

Twelve patients (six women and six men; mean age, 61.3 years; range, 47–78 years) who presented with PASC as documented by pathologic examination underwent CT (n= 10) or both CT and MRI (n= 2) examination. Two radiologists evaluated the images and determined the location, size, margin, internal attenuation or signal intensity, contrast enhancement, and pattern for each tumor. Additionally, the presence of poorly enhanced areas, upstream main pancreatic duct (MPD) dilatation, pancreatic atrophy, and peripancreatic tissue metastasis were evaluated. Images were cross-referenced to surgical and pathologic findings.

Results

Masses were distributed throughout the pancreas (head, n= 6; body, n= 1; and tail, n= 5). The tumor size ranged from 2.4 to 5.5 cm with an average size of 3.7 cm. Eight (66.7%) masses were ill defined, and seven (58.3%) were partially exophytic. Twelve (100%) masses showed heterogeneous and poorly enhanced areas. The lesions showed weak (n= 5), moderate (n= 5), or intense (n= 2) progressive enhancement. The diameter of MPD in six patients ranged from 3.0 to 5.0 mm with an average of 3.7 mm. Pancreatic atrophy was not found. In 10 patients (83.3%), masses invaded the peripancreatic tissues. Two patients had metastatic liver disease at presentation.

Conclusion

PASC typically presented as an ill-defined, hypovascular mass with a poorly enhanced area, exophytic tendency, and peripancreatic tissue invasion. Lack of pancreatic atrophy and mild MPD dilatation were also distinct from common duct pancreatic adenocarcinoma.

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.

Section snippets

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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