The occurrence of hepatocellular carcinoma (HCC) is closely associated with viral hepatitis or alcoholic hepatitis. Although active surveillance is ongoing in Korea, advanced or metastatic HCC is found at initial presentation in many patients. Metastatic HCC presents with a hypervascular intrahepatic tumor and extrahepatic lesions such as lung or lymph node metastases. Cases of HCC presenting as carcinoma of unknown primary have been rarely reported. The authors experienced a case of metastatic HCC in a patient who presented with a metastatic bone lesion but no primary intrahepatic tumor. This case suggests that HCC should be considered as a differential diagnosis when evaluating the primary origin of metastatic carcinoma. (Korean J Gastroenterol 2015;66:50-54)

Atypical antipsychotics, which have better efficacy and fewer side effects compared to first-generation antipsychotics, are being used increasingly for the treatment of schizophrenia. However, adverse events such as weight gain, diabetes mellitus and abnormal lipid profile have been reported in patients treated with these agents. Diabetic ketoacidosis (DKA) is a rare side effect of atypical antipsychotics, but deserves attention due to its severity. Although various atypical antipsychotics have been reported as causing DKA, there have been no reports showing an association with DKA and paliperidone, which is a recently developed antipsychotic agent. Here, we report two cases of DKA in patients with paliperidone therapy. Both cases had no history of diabetes before use of paliperidone, and DKA was manifested within 2 years of starting paliperidone therapy. Like other atypical antipsychotics, use of paliperidone warrants monitoring for metabolic derangements including DKA.