**Core Concept**
Mazabraud's syndrome is a rare genetic disorder characterized by the association of fibrous dysplasia with soft tissue tumors, typically myxomas. This condition is often linked to mutations in the GNAS gene, which plays a crucial role in cell growth and differentiation.

**Why the Correct Answer is Right**
The correct answer involves the understanding of Mazabraud's syndrome as a distinct clinical entity, where the presence of fibrous dysplasia is accompanied by the development of soft tissue tumors, particularly myxomas. This occurs due to the aberrant expression of the GNAS gene, which normally regulates cell growth and differentiation. The resulting myxomas are benign tumors composed of myxoid tissue, which can occur in various parts of the body, including the bone, muscle, and soft tissues.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because Mazabraud's syndrome is not primarily associated with osteogenesis imperfecta, a condition characterized by brittle bones and often linked to mutations in the COL1A1 and COL1A2 genes.

**Option B:** This option is incorrect because McCune-Albright syndrome is a distinct clinical entity characterized by the triad of polyostotic fibrous dysplasia, café-au-lait skin spots, and precocious puberty, often caused by mutations in the GNAS gene. While both conditions share some similarities, they are not the same.

**Option C:** This option is incorrect because Gorham-Stout disease is a rare condition characterized by the progressive replacement of bone with lymphatic tissue, leading to bone destruction and deformity. It is not directly associated with the development of soft tissue tumors.

**Option D:** This option is incorrect because this is a distractor and not a valid option.

**Clinical Pearl / High-Yield Fact**
Mazabraud's syndrome is a rare condition that highlights the importance of considering genetic mutations in the diagnosis of fibrous dysplasia. The presence of soft tissue tumors, particularly myxomas, should prompt further investigation into the underlying genetic cause of the condition.

**Correct Answer:** B.