Imaging description

The term malignant masquerade [1] refers to benign idiopathic fibroinflammatory stricturing of the common hepatic duct confluence that is clinically and radiologically (Figure 23.1) indistinguishable from hilar cholangiocarcinoma (Klatskin tumor).

Importance

While, virtually by definition, malignant masquerade cannot be diagnosed by imaging alone, recognition of this pseudotumor emphasizes the importance of offering surgery to all patients with what appears to be a resectable hilar cholangiocarcinoma. Palliative treatment of these patients, particularly with metallic endobiliary stenting, is rarely appropriate without a histological diagnosis because the assumption of malignancy may be incorrect and because such treatment may complicate or preclude subsequent surgery.

Typical clinical scenario

Studies have consistently shown that 5 to 10% of patients with a presumptive preoperative diagnosis of hilar cholangiocarcinoma are ultimately found to have an idiopathic benign stricture at final histopathological review [2].

Differential diagnosis

Benign idiopathic fibroinflammatory strictures of the common hepatic duct confluence appear to represent several different histopathological entities, including lymphoplasmacytic sclerosing pancreatitis and cholangitis, primary sclerosing cholangitis, granulomatous disease, non-specific fibrosis and inflammation, and occult stone disease [2].Lymphoplasmacytic sclerosing pancreatitis and cholangitis is a distinct and relatively recently recognized autoimmune disorder [3] which may primarily manifest in the pancreas (where it is also known as lymphoplasmacytic sclerosing pancreatitis or autoimmune pancreatitis) but can also primarily affect the biliary system [4].