Rare coexistence of mediastinal hepatoid adenocarcinoma, idiopathic azoospermia and horseshoe kidney: a case report and review of the literature.

Hepatoid adenocarcinoma (HAC) is the term proposed for a special type of extrahepatic tumors, which is similar to the hepatocellular carcinoma (HCC) both in the histopathology and immunohistochemistry. HAC has been observed in the stomach, colon, pancreas, gall bladder, lung and female genital tract, but rarely in the mediastinum. Now we describe a case of a 28-year-old Chinese male with primary mediastinal HAC with lung and liver metastasis. In this patient, HAC was associated with horseshoe kidney and idiopathic nonobstructive azoospermia. It seemed derivation abnormalities during organogenesis in the embryo stage played a significant role in the pathogenesis of HAC, horseshoe kidney and idiopathic nonobstructive azoospermia. Even the pathogenesis was still unknown; it may merit consideration of HAC together with horseshoe kidney and idiopathic nonobstructive azoospermia as a syndrome rather than as a spectrum of coincidental diseases. Furthermore, we found the HAC is a neoplasm with unfavorable outcomes despite aggressive and multi-protocol strategies. The serum alpha fetoprotein (AFP) should be regarded as a useful marker for diagnostic purposes and therapeutic response evaluation of HAC.