**Core Concept**
The Lighthouse sign is a radiological finding associated with a specific condition, which is characterized by a unique appearance on imaging studies. This sign is relevant to the diagnosis and management of a particular disease process.

**Why the Correct Answer is Right**
The Lighthouse sign is seen in the context of a pancreatic pseudocyst, where it is observed as a thin, linear or curved wall of a pseudocyst that is adjacent to the pancreatic duct. The pseudocyst wall appears as a bright, thin structure on imaging, resembling the beam of a lighthouse, which is a characteristic feature of this condition. This sign is often seen on CT scans or MRI.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the Lighthouse sign is not associated with a pancreatic abscess, which would have a different appearance on imaging.
**Option B:** This option is incorrect because the Lighthouse sign is not seen in the context of a pancreatic tumor, where the appearance would be different and not resemble a lighthouse beam.
**Option C:** This option is incorrect because the Lighthouse sign is not associated with a pancreatic cyst, which would have a different imaging appearance.

**Clinical Pearl / High-Yield Fact**
The Lighthouse sign is an important radiological finding that can help diagnose pancreatic pseudocysts, which are a common complication of pancreatitis. It is essential to recognize this sign to avoid misdiagnosis and ensure appropriate management.

**Correct Answer:** C.