**Core Concept**
Non-bacterial thrombotic endocarditis (NBTE) is a form of endocarditis characterized by the deposition of sterile vegetations on heart valves, often associated with hypercoagulable states, malignancy, and systemic lupus erythematosus (SLE). The pathogenesis of NBTE involves the formation of sterile vegetations due to the interaction of platelets, fibrin, and endothelial cells.

**Why the Correct Answer is Right**
The correct answer is not commonly associated with NBTE because NBTE is typically seen in the context of malignancy, SLE, and hypercoagulable states, whereas the other options are more commonly associated with infectious endocarditis. The vegetations in NBTE are sterile and do not contain microorganisms, which distinguishes it from bacterial endocarditis.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because cancer is a known risk factor for NBTE, and the vegetations in NBTE are often associated with malignancy.
**Option B:** This option is incorrect because SLE is a systemic autoimmune disease that can cause NBTE due to the formation of antiphospholipid antibodies and hypercoagulability.
**Option C:** This option is incorrect because while it is true that NBTE can occur in the absence of a clear source of infection, this does not mean that it is not associated with NBTE.

**Clinical Pearl / High-Yield Fact**
NBTE is often seen in patients with malignancy, SLE, and hypercoagulable states, and the vegetations are typically sterile. It is essential to differentiate NBTE from bacterial endocarditis based on the absence of microorganisms in the vegetations.

**Correct Answer: D.**