Peripheral T- cell lymphoma (PTCL) is a rare form of non-Hodgkin's lymphoma(NHL). Primary liver involvement in NHL is uncommon, and the most common histological type is diffuse large B- cell lympoma. Primary hepatic PTCL is exceedingly rare. We present a case of a 37-year old male with worsening juandice and abdominal pain, diagnosed with PTCL not otherwise specified (PTCL- NOS) primarily arising from liver with high Ki- 67 expression, suggesting a poor prognosis. A 37-year-old male with no significant medical history presented for persistent jaundice and right upper quadrant pain since 1 month. History was also positive for decreased appetite and weight loss of 10 lbs over the past two months. He denied alcohol abuse. Physical examination revealed mild icterus and abdominal distension. Laboratory results noted total bilirubin of 5.7 mg/dL, alkaline phosphatase 1005 IU/L, albumin 3.2 g/dL, and AST/ALT of 257/239 U/L. Viral hepatitis serology for A, B and C were negative. Anti nuclear antibody, anti mitochondrial antibody, and anti smooth muscle antibody were nonreactive. Epstein-Barr virus serology indicated past infection and CMV not detected. Serum ceruloplasmin, transglutaminase IgG and IgA, thyroid-stimulating hormone, alpha 1 antitrypsin were all normal. MRI abdomen showed mild intrahepatic biliary duct dilation. Common hepatic duct was normal in caliber. No discrete liver mass was visualized. Liver biopsy showed T-lineage lymphoma favoring PTCL- NOS with proliferation index of 70% by labeling for Ki-67/mib1 [Figure 1]. The patient was transferred to a tertiary care center for further management where he had a bone marrow biopsy, which was negative for malignancy, further supporting hepatic origin. He was started on chemotherapy but subsequently developed sepsis and expired. Primary hepatic PTCL is rare and aggressive form of NHL, which requires a robust treatment regimen. Patients usually present early with abnormal liver enzymes but diagnosis can be challenging due to the presence of multiple granulomas, histiocytosis, and focal neoplastic infiltrate. These tumors have been shown to respond well to chemotherapy. Early diagnosis and treatment is therefore critical for a favorable prognosis.Figure: A - Large dense clusters of atypical T-lymphocytes (20X). B - Atypical T-lymphocytes (100X). C - CD2 positive (40X). D - CD3 positive (20X). E - CD4 positive (20X). F - CD79a scantly positive (20X).