An unexpected diagnosis of ectopic liver diagnosed by fine needle aspiration.

The differential diagnosis of perigastric masses is broad, ranging from benign to malignant entities. Among the benign entities, accessory liver lobes and ectopic liver are unusual and often incidentally discovered. Here, we report a patient with malignant melanoma who was clinically suspected to have a perigastric metastasis or a gastrointestinal stromal tumor but was ultimately diagnosed by fine needle aspiration (FNA) to have benign ectopic liver. A 47-year-old male was diagnosed with malignant melanoma of the scalp in May 2015 at a tertiary care hospital. He was found to have a 2.6 cm enhancing mass adjacent to the fundus of the stomach and below the diaphragm by computed tomography imaging. To exclude metastasis, the patient was referred to endoscopy, and an endoscopic ultrasound-guided FNA was performed with rapid on-site evaluation (ROSE) by a cytopathologist. A relatively new FNA needle (Shark Core) was used, which produced useful core biopsy material. Cytopathology demonstrated flat sheets, single cells, and small clusters of polygonal cells. There was abundant granular cytoplasm, often containing pigment. Cells lacked pleomorphism. The smear findings appeared consistent with hepatocytes. The cell block demonstrated small core fragments of hepatic parenchyma with portal tracts. Immunohistochemistry for arginase-1 confirmed that this was hepatic tissue. ROSE was useful for communicating with the endoscopist that the mass was both far from, and not connected to, the liver. This is the first documented account of perigastric ectopic liver diagnosed by FNA. This entity should be considered in the differential of perigastric masses.