Keywords

Clinical History

30-year-old man with history of cystic fibrosis.

Imaging Findings

Axial contrast-enhanced CT image demonstrates diffuse fatty attenuation of the pancreatic parenchyma (Fig. 1a, thick white arrow). The pancreatic duct can be appreciated (Fig. 1a, thin arrow). There is heterogeneous appearance of the liver with multiple mass-like areas of low attenuation (Fig. 1a, black arrow). On a non-contrast CT image, the multiple mass-like areas of low attenuation (Fig. 1b, arrows) measure about 1 HU (range, −25–10 HU).

figure 1

Fig. 1

Differential Diagnosis

Cystic fibrosis, Shwachman-Diamond syndrome, post steroid therapy, Cushing’s syndrome, and Johanson-Blizzard syndrome.

Diagnosis

Diffuse fatty replacement of the pancreas secondary to cystic fibrosis.

Discussion

The pancreas is the most common organ in the abdomen involved in cystic fibrosis, which can present as complete fatty replacement of the organ. Reduced flow in the pancreatic duct caused by inspissated secretions leads to fibrofatty replacement of the organ. Ductal stenosis can also lead to cyst formation [1]. The mean age at which pancreatic fatty replacement is diagnosed is 17 years and correlates with exocrine insufficiency of the organ [2, 3]. Exocrine insufficiency affects about 90% of patients with cystic fibrosis and can, in turn, lead to steatorrhea due to fat malabsorption. Residual pancreatic exocrine function may cause acute recurrent pancreatitis, and acute pancreatitis, on rare occasions, may be the initial presentation of cystic fibrosis [4]. Secretin-stimulated MRI/MRCP has shown high diagnostic accuracy for diagnosing exocrine insufficiency in patients with cystic fibrosis [5]. Endocrine insufficiency is less common, affecting about 30–40% of patients with cystic fibrosis, and can lead to a combination of type 1 and 2 diabetes mellitus [6].

On CT, the attenuation of the pancreas in diffuse fatty replacement of the pancreas secondary to cystic fibrosis is similar that of the mesenteric fat (Fig. 1a). The contour of the pancreas can be appreciated and the pancreatic duct may be visualized within area of lipomatous change (Fig. 1). Cystic change may also occur and when it does the cysts are usually unilocular (Fig. 2). Other imaging findings include partial fatty replacement [7], pancreatic parenchymal calcifications, and diffuse pancreatic atrophy without fatty replacement [8]. The radiographic severity of acute pancreatitis in patients with cystic fibrosis is usually less severe than patients without cystic fibrosis.

Fig. 2
figure 2

Companion case. 42-year-old man with cystic fibrosis. Axial contrast-enhanced CT demonstrates complete fatty replacement of the pancreas (Fig. 2, thick arrow) and a retention cyst in the pancreatic head (Fig. 2, thin arrow)

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Hepatic steatosis is seen in about 23–67% of patients with cystic fibrosis and is the most common finding in the liver [9]. Fatty replacement may have a mass-like appearance presenting as multiple pseudomasses in the liver [10] (Fig. 1b).

Similar diffuse fatty replacement of the pancreas is also seen in patients with Shwachman-Diamond syndrome (Fig. 3). However, unlike cystic fibrosis, calcifications and cyst formation do not occur in Shwachman-Diamond syndrome [11]. Other rare causes of fatty infiltration of the pancreas are steroid therapy, Cushing’s syndrome, and Johanson-Blizzard syndrome [12].

Fig. 3
figure 3

Companion case. 20-year-old woman with Shwachman-Diamond syndrome. Axial contrast-enhanced CT demonstrates complete fatty replacement of the pancreas (arrow)

Full size image

Confirmatory test for cystic fibrosis may be made with genetic testing for cystic fibrosis transmembrane conductance regulator (CFTR) gene. The survival of patients with cystic fibrosis has improved over the years with lung transplantation, better nonsurgical therapies, and nutrition supplementation.

Teaching Point

The pancreas is the most common organ involved in cystic fibrosis in the abdomen and presents as complete fatty replacement and cyst formation with or without calcifications.