**Core Concept**
Hepatocellular carcinoma (HCC) is a primary malignancy of the liver, often arising in the setting of chronic liver disease, cirrhosis, or hepatitis B/C infection. HCC is characterized by uncontrolled cell growth, invasion, and metastasis.

**Why the Correct Answer is Right**
HCC typically presents with a combination of clinical and radiological features, including weight loss, abdominal pain, jaundice, and a palpable liver mass. The most common histological features of HCC include hepatocyte dysplasia, atypical mitoses, and vascular invasion. Given the aggressive nature of HCC, it is rare for the tumor to remain entirely asymptomatic and small in size.

**Why Each Wrong Option is Incorrect**
**Option A:** HCC can indeed cause weight loss, but this is not the most unlikely feature. Weight loss is a common symptom of advanced HCC due to tumor-induced malnutrition and metabolic changes.
**Option B:** HCC often presents with a palpable liver mass, which is a key feature of this malignancy. Therefore, this option is not the most unlikely feature of HCC.
**Option C:** HCC can be associated with various systemic and paraneoplastic syndromes, including hypoglycemia, hypercalcemia, and erythrocytosis. While these syndromes are not universal, they are not the most unlikely features of HCC either.

**Clinical Pearl / High-Yield Fact**
A key aspect of HCC diagnosis is the presence of a characteristic pattern of vascular invasion, often seen on imaging studies. This feature can help differentiate HCC from other liver lesions, such as metastases or benign tumors.

**Correct Answer:** D.