Which lesion is not encapsulated?

Which lesion is not encapsulated?

• A. Focal Nodular Hyperplasia (FNH)
• B. Hemangioma
• C. Infantile Hemangioendothelioma
• D. Kasabach-Merritt syndrome

Answer: (A)

The main idea here is how a lesion’s border appears on imaging and whether there is a true capsule surrounding it. Focal nodular hyperplasia is classically non-encapsulated: its border blends with the surrounding liver parenchyma, and its defining features include a central scar and a mosaic of hepatocytes and abnormal vessels rather than a distinct fibrous capsule. Because there isn’t a true fibrous capsule encasing FNH, it is described as not encapsulated. In contrast, the other vascular liver lesions are typically seen as well-defined masses with a capsule or capsule-like rim, which helps separate them from the surrounding tissue on ultrasound. Kasabach-Merritt syndrome describes a coagulopathy associated with certain vascular tumors rather than a single encapsulated lesion, and infantile hemangioendothelioma and hemangioma usually present as discrete, well-demarcated lesions with capsule or capsule-like borders.

The main idea here is how a lesion’s border appears on imaging and whether there is a true capsule surrounding it. Focal nodular hyperplasia is classically non-encapsulated: its border blends with the surrounding liver parenchyma, and its defining features include a central scar and a mosaic of hepatocytes and abnormal vessels rather than a distinct fibrous capsule. Because there isn’t a true fibrous capsule encasing FNH, it is described as not encapsulated.

In contrast, the other vascular liver lesions are typically seen as well-defined masses with a capsule or capsule-like rim, which helps separate them from the surrounding tissue on ultrasound. Kasabach-Merritt syndrome describes a coagulopathy associated with certain vascular tumors rather than a single encapsulated lesion, and infantile hemangioendothelioma and hemangioma usually present as discrete, well-demarcated lesions with capsule or capsule-like borders.