**Core Concept**
SAPHO syndrome is a rare disorder characterized by the association of skin and bone manifestations. It is a form of acne inversa, also known as hidradenitis suppurativa, combined with osteoarticular manifestations, such as osteitis and arthralgias.

**Why the Correct Answer is Right**
The SAPHO syndrome components include acne inversa (hidradenitis suppurativa), osteitis (inflammation of bone), and arthralgias (joint pain). The acronym SAPHO was coined by Salli et al. in 1984, and it stands for Synovitis, Acne, Pustulosis, Hyperostosis, and Osteitis. The syndrome is thought to result from an abnormal immune response to bacterial or fungal infections, leading to inflammation of the skin and joints.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because SAPHO syndrome does not typically involve the gastrointestinal system. While some cases may have extraintestinal manifestations, the primary components of SAPHO syndrome are skin and bone-related.
**Option B:** This option is incorrect because SAPHO syndrome does not typically involve the cardiovascular system. While some cases may have systemic inflammation, the primary components of SAPHO syndrome are skin and bone-related.
**Option C:** This option is incorrect because SAPHO syndrome does not typically involve the neurological system. While some cases may have systemic symptoms, the primary components of SAPHO syndrome are skin and bone-related.

**Clinical Pearl / High-Yield Fact**
The SAPHO syndrome is a rare but important diagnosis to consider in patients with skin and bone manifestations, particularly in cases of acne inversa and osteoarticular inflammation. Early recognition and treatment can help prevent long-term damage and improve quality of life.

**Correct Answer: D.**