What is the most likely underlying cause of a 2-month-old girl's presentation with plagiocephaly (flatness of the back of the head), torticollis (abnormal neck posture), and a firm mass in the sternocleidomastoid muscle?

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Differential Diagnosis

  • Single most likely diagnosis
    • C. Postural deformity of the neck: The patient's presentation of flattening of the right occiput, anterior displacement of the right ear and forehead, and preference to tilt her head to the left while rotating the chin to the right is consistent with a postural deformity of the neck, also known as torticollis. The firm mass in the inferior portion of the left sternocleidomastoid muscle further supports this diagnosis, as it is likely a sternocleidomastoid tumor or fibromatosis colli, which is often associated with torticollis.
  • Other Likely diagnoses
    • D. Premature closure of a cranial suture: Although less likely, premature closure of a cranial suture (craniosynostosis) could cause asymmetrical head shape. However, the presence of a firm mass in the sternocleidomastoid muscle and the patient's preference for head positioning suggest that torticollis is a more likely cause.
  • Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
    • E. Tumor of the posterior fossa: Although rare, a tumor in the posterior fossa could cause torticollis and asymmetrical head shape. It is essential to consider this possibility, as it would require prompt diagnosis and treatment.
  • Rare diagnoses
    • A. Congenital lymphatic malformation: This condition could cause a mass in the neck, but it would not typically cause the patient's head to be tilted to one side or result in a firm mass in the sternocleidomastoid muscle.
    • B. Fracture of the clavicle: A fracture of the clavicle could cause discomfort and asymmetry, but it would not typically cause the patient's head to be tilted to one side or result in a firm mass in the sternocleidomastoid muscle.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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