Atypical presentation of a chondrosarcoma metastasis

Clinical History

We present a case of a 62-year old woman with a past history of a left thigh chondrosarcoma, surgically removed in 2010 and without signs of recurrence or metastatic disease. A follow-up abdominal-pelvic CT was performed.

Imaging Findings

A calcified nodule with a thin hypodense halo, measuring approximately 9 mm, was identified in the pancreatic tail (Figure 1). Retrospectively, this lesion was already present in previous CT studies from 2014 and 2015 (Figure 2), with obvious growth in the present study. Approximately four months after the last CT scan the patient underwent a MRI exam, that showed an apparent increase in dimensions of the pancreatic lesion (28 mm). This lesion was hypointense on T1-weighted MR-imaging and slightly hyperintense in T2- weighted images (Figure 3). At the periphery of the nodule there was enhancement after contrast administration (Figure 4) and abnormal diffusion restriction (high signal on diffusion weighted images and low ADC-values) (Figure 5). A FDG-PET/CT scan was then performed, showing uptake in the pancreatic tail (Figure 6). The patient agreed to undergo surgery and pathology confirmed the diagnosis of a calcified chondrosarcoma metastasis.

Discussion

Pancreatic metastasis are rare, accounting for about 2% of all pancreatic malignancies [1] and found at autopsy in a minority (3-12%) of patients with widespread metastatic disease [2]. They usually are secondary to gastric, kidney, breast, lung, melanoma and colon cancer [3]. In the even rarer cases of metastasis calcification, patients usually have a past history of colonic cancer or renal cell carcinoma [3].
Most metastasis to the pancreas are asymptomatic and found incidentally [4], most commonly with small dimensions and without a predilection for any part of the pancreatic gland [3]. When large and located at the head or body of the gland, common bile duct and pancreatic ductal obstruction can occur, with resulting symptoms such as jaundice and weight loss [5].
Imaging findings are non-specific. In most cases (50-73%), pancreatic metastasis present in CT scans as a well circumscribed mass, iso to hypodense relative to normal pancreas before contrast administration [4]. Most pancreatic metastases exhibit heterogeneous enhancement [3], particularly when large, showing peripheral enhancement around a central hypodense area [4]. Metastasis calcification occurs in a minority of the cases [3].
Most pancreatic calcifications occur in association with chronic pancreatitis [6] (usually secondary to alcohol abuse), and can be found in 30-50% of these patients [7]. However, calcifications due to chronic pancreatitis are usually multiple, irregular and small, more commonly involving the pancreatic head than the tail [6]. Besides that, calcifications due to chronic pancreatic inflammation are usually accompanied by other pancreatic changes, namely dilation of the main pancreatic duct, glandular atrophy and pancreatic pseudocysts. Pancreatic ductal adenocarcinoma (the most common primary pancreatic tumor) can also appear with calcifications when the tumor develops in a pancreas with underlying chronic calcific pancreatitis [6]. However, typical findings of chronic pancreatitis were not present in our case.
Pancreatic serous cystadenoma most commonly occurs in females (especially over 60 years old) [6] and can present a central calcified scar as a result of the coalescence of multiple fibrous septa [8]. Still, these tumors usually occur in the pancreatic head and the central scar is surrounded by multiple tiny cysts, separated by peripheral calcified septations (the sunburst pattern) [6], findings also not obvious in the case we present.

Differential Diagnosis List

Final Diagnosis

Calcified chondrosarcoma metastasis in the pancreas.

URL:	https://eurorad.org/case/14964
DOI:	10.1594/EURORAD/CASE.14964
ISSN:	1563-4086