**Core Concept**
The earliest radiological change in acute osteomyelitis is related to the inflammatory response and bone destruction. **Osteomyelitis** is an infection of the bone, usually caused by bacteria, and the initial changes can be subtle.

**Why the Correct Answer is Right**
The correct answer is related to the soft tissue changes and the initial bone resorption that occurs before more pronounced bone destruction is visible on radiographs. In the early stages of osteomyelitis, there might not be significant changes visible on plain X-rays, but **soft tissue swelling** and **periosteal reaction** can be early indicators.

**Why Each Wrong Option is Incorrect**
**Option A:** This choice is incorrect because it refers to a later stage of bone infection.
**Option B:** This is also incorrect as it is not the earliest change.
**Option C:** Similarly, this option does not represent the initial radiological finding in acute osteomyelitis.
**Option D:** This choice is incorrect as well because the earliest changes are more related to soft tissues and initial bone reaction rather than the formation of a distinct entity.

**Clinical Pearl / High-Yield Fact**
An important point to remember is that early diagnosis of osteomyelitis often relies on clinical suspicion and laboratory findings, as radiological changes may lag behind the onset of symptoms.

**Correct Answer:** D. Soft tissue swelling