A Study of the Efficacy and Safety of Apremilast (CC-10004) in Subjects With Moderate to Severe Plaque Psoriasis of the Scalp

The study will consist of four phases: * Screening Phase - up to 35 days * Double-blind Placebo-controlled Phase- Weeks 0 to 16 Subjects will receive treatment with one of the following: * apremilast 30 mg tablets orally BID or * placebo tablets (identical in appearance to apremilast 30 mg tablets) orally BID * Apremilast Extension Phase - Weeks 16 to 32 * All subjects who had received placebo during the placebo-controlled phase will be switched to apremilast 30 mg BID (or continue with) apremilast. At Week 16, all subjects will maintain this dosing through Week 32. * Observational Follow-up Phase * Four-week Post-Treatment Observational Follow-up Phase for all subjects who complete the study or discontinue from the study early.