[Diagnosis of an accessory liver lobe established by magnetic resonance imaging-guided core biopsy]

An accessory liver is a rare developmental anomaly. There are two subtypes: the accessory liver lobe (ALL), which is connected to the liver and the true ectopic liver. An accessory liver is usually of no clinical relevance in spite of the very rare cases in which torsion or other complications may cause serious problems. This anomaly should not be misinterpreted as a malignant tumour. We report the case of an accessory liver lobe, located below the left diaphragm, which was misdiagnosed as a metastasis of a known malignant melanoma. The diagnosis ALL was established by a biopsy under guidance of magnetic resonance tomography (MRT). In our opinion, an accessory liver and its appearance should be known, to include this entity in differential diagnosis of perihepatic masses.