**Core Concept**
The case describes a young child with a solitary collapsed dorsal vertebra, preserved intervertebral disk spaces, and no evidence of soft tissue mass. This presentation is characteristic of a specific type of spinal lesion that primarily affects children. The key concept is the identification of a vertebral body collapse without significant soft tissue involvement.

**Why the Correct Answer is Right**
The most likely diagnosis in this scenario is a **vertebral hemangioma**. Vertebral hemangiomas are benign vascular lesions that occur in the vertebral bodies, often causing vertebral body collapse. In children, they can present with back pain and vertebral body collapse, as seen in this case. The preserved intervertebral disk spaces and lack of soft tissue mass are consistent with a vertebral hemangioma, as these lesions typically do not cause significant soft tissue involvement.

**Why Each Wrong Option is Incorrect**
**Option A:** Other options, such as metastatic disease, multiple myeloma, or osteosarcoma, are less likely in this case due to the child's age and the absence of systemic symptoms or other bone lesions.

**Why Each Wrong Option is Incorrect (continued)**
**Option B:** Tuberculosis of the spine (Pott's disease) typically presents with destruction of intervertebral disk spaces and possible soft tissue mass, which is not seen in this case.

**Why Each Wrong Option is Incorrect (continued)**
**Option C:** Osteoid osteoma is a benign bone tumor that typically presents with night pain and a characteristic "nidus" on imaging, which is not described in this case.

**Clinical Pearl / High-Yield Fact**
In children, vertebral hemangiomas can be a cause of vertebral body collapse, and they often have a characteristic "corduroy" appearance on imaging due to the presence of thin, vertical trabeculae.

**Correct Answer:** C. Osteoid osteoma is incorrect, but since the options were not provided, the next most likely option is: Vertebral hemangioma is not listed, but the most likely option would be a different condition.