Obesity results in hepatic fat accumulation, i.e., steatosis. In addition to fat overload, impaired fatty acid β-oxidation also promotes steatosis. Fatty acid β-oxidation takes place in the mitochondria and peroxisomes. Usually, very long-chain and branched-chain fatty acids are the first to be oxidized in peroxisomes, and the resultant short chain fatty acids are further oxidized in the mitochondria. Peroxisome biogenesis is regulated by peroxin 16 (PEX16). In liver-specific PEX16 knockout (Pex16^Alb-Cre) mice, hepatocyte peroxisomes were absent, but hepatocytes proliferated, and liver mass was enlarged. These results suggest that normal liver peroxisomes restrain hepatocyte proliferation and liver sizes. After high-fat diet (HFD) feeding, body weights were increased in PEX16 floxed (Pex16^fl/fl) mice and adipose-specific PEX16 knockout (Pex16^AdipoQ-Cre) mice, but not in the Pex16^Alb-Cre mice, suggesting that the development of obesity is regulated by liver PEX16 but not by adipose PEX16. HFD increased liver mass in the Pex16^fl/fl mice but somehow reduced the already enlarged liver mass in the Pex16^Alb-Cre mice. The basal levels of serum triglyceride, free fatty acids, and cholesterol were decreased, whereas serum bile acids were increased in the Pex16^Alb-Cre mice, and HFD-induced steatosis was not observed in the Pex16^Alb-Cre mice. These results suggest that normal liver peroxisomes contribute to the development of liver steatosis and obesity.

Laryngeal lymphoepithelial carcinoma (LEC) is a rare and diagnostically complex malignancy, often overlooked due to its nonspecific presentation and common association with smoking. Prompt and accurate diagnosis is crucial for achieving optimal patient outcomes. A 63-year-old Chinese male with a two-year history of persistent hoarseness and throat discomfort initially diagnosed as chronic inflammation. However, further evaluation revealed vestibular fold swelling and right vocal cord thickening. Surgical resection confirmed laryngeal LEC with a Schmincke pattern, CD20+ B-cell infiltration, positive cytokeratin (CK) and p40 immunostaining, and negative Epstein-Barr virus-encoded RNA (EBER). Following radiotherapy, the patient experienced symptomatic improvement. Laryngeal LEC is often EBER-negative and challenging to diagnose. This case highlights the need to consider LEC even with benign-appearing findings. Accurate diagnosis relies on detailed histology and IHC, especially CK and p40.Radiotherapy is an effective treatment for EBER-negative laryngeal LEC. Laryngeal LEC is a smoking-associated, EBER-negative rare malignancy that typically responds well to radiotherapy, yielding a favorable prognosis. This case underscores the necessity of considering laryngeal LEC in similar clinical presentations to avoid misdiagnosis.