Cholangiocarcinoma following orthotopic liver transplantation: A unique pattern of recurrence diagnosed using immunohistochemical stains

Tumor recurrence is an important complication following liver resection or transplantation for primary liver malignancy. We describe and immunohistochemically characterize a unique pattern of recurrent cholangiocarcinoma in a 45-year-old woman after orthotopic liver transplantation. In routine histologic sections, cytologically malignant cells infiltrated sinusoidal channels and occasionally simulated atypical Kupffer cells. Immunoperoxidase markers for low-molecular-weight cytokeratins highlighted these malignant cells and established their epithelial character. The presence of malignant cells within sinusoids may be subtle and requires careful evaluation of biopsy material. In appropriately selected cases, immunoperoxidase stains for cytokeratins may help in the detection of recurrent primary tumors of the liver.