Differential Diagnosis for a 12-year-old boy with a left neck mass
- Single most likely diagnosis
- B. Branchial cleft cyst: This is the most likely diagnosis due to the presence of a cystic neck mass, a small pit anterior to the sternocleidomastoid muscle, and leakage of mucopurulent fluid. The history of a recent upper respiratory tract infection and the development of a painful lump in the neck also supports this diagnosis, as branchial cleft cysts can become infected and present with these symptoms.
- Other Likely diagnoses
- A. Actinomyces lymphadenitis: This is a possible diagnosis, given the patient's history of a recent infection and the presence of a neck mass with mucopurulent drainage. Actinomyces infections can cause abscesses and sinus tracts, which could explain the leakage of fluid from the pit.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Tuberculous lymphadenitis: Although not listed among the options, tuberculous lymphadenitis is a critical diagnosis to consider in a patient with a neck mass and a history of infection. It can present with similar symptoms, including a painful mass and drainage, and is a potentially life-threatening condition if left untreated.
- Malignancy (e.g., lymphoma): Although less likely, malignancy is always a concern in a patient with a persistent neck mass, especially if there are systemic symptoms such as fever or weight loss.
- Rare diagnoses
- C. Cystic hygroma: This is a congenital anomaly that typically presents at birth or in early childhood, making it less likely in a 12-year-old boy.
- D. Laryngocele: This is a rare condition that typically presents with a neck mass and respiratory symptoms, such as stridor or dyspnea, which are not mentioned in the case.
- E. Thyroglossal duct cyst: This is a congenital anomaly that typically presents as a midline neck mass, which does not match the patient's presentation of a left-sided mass.