Differential Diagnosis for Hard Right Bony Prominence on Posterior Right Side of the Neck

Single Most Likely Diagnosis

• Cervical Rib: A cervical rib is an extra rib that forms above the first rib, which can cause a hard bony prominence on one side of the neck. It is a congenital anomaly and can be unilateral, explaining the asymmetry.

Other Likely Diagnoses

• Torticollis with Bony Deformity: Torticollis is a condition where the head becomes persistently turned to one side. Over time, it can lead to bony deformities, including a prominence on the affected side due to muscle and bone adaptations.
• Hemivertebra or Other Congenital Spinal Anomalies: These are congenital anomalies of the spine where one side of a vertebra fails to develop fully, leading to an abnormal lateral curvature of the spine (scoliosis) and potentially a noticeable bony prominence on one side of the neck.
• Fracture or Malunion of a Cervical Vertebra: A fracture that heals improperly (malunion) can result in a bony deformity or prominence, especially if it involves one of the cervical vertebrae.

Do Not Miss Diagnoses

• Meningocele or Myelomeningocele: Although rare, these conditions involve protrusions of the meninges or spinal cord through a defect in the spine. They can present with a bony prominence and are critical to diagnose early due to potential neurological implications.
• Osteomyelitis or Bone Tumor: Infections (osteomyelitis) or tumors of the bone in the cervical spine can cause a hard prominence. These conditions require prompt diagnosis and treatment to prevent serious complications.

Rare Diagnoses

• Klippel-Feil Syndrome: A rare congenital condition characterized by the fusion of any two of the seven cervical vertebrae, which can lead to a webbed neck and potentially a bony prominence.
• Sprengel's Deformity: A rare congenital anomaly where one shoulder blade sits higher on the back than the other, potentially causing a noticeable asymmetry and bony prominence in the neck area.

Each of these diagnoses has a different set of implications for patient care, ranging from observation for congenital anomalies to urgent intervention for infections or tumors. A thorough clinical evaluation, including imaging studies, is necessary to determine the cause of the bony prominence.