Sinusoidal Hepatic Growth Pattern of Metastatic DICER1-Mutated Urethral Sarcoma Mimicking Hepatocellular Carcinoma.

Although liver metastases from solid tumors are common and typically present as discrete masses, a sinusoidal pattern of hepatic involvement is rare, especially in sarcomas. We report a case of DICER1-mutated urethral sarcoma exhibiting this unusual metastatic pattern, with features mimicking hepatocellular carcinoma (HCC). Immunohistochemical analysis revealed focal nodular hyperplasia-like changes rather than HCC, attributed to tumor cell infiltration of hepatic sinusoids and consequent alterations in blood flow. Recognizing this distinct metastatic pattern is essential, as it can be overlooked on both imaging and histologic evaluation.