We report the case of a 66-year-old man with a cervical neck mass located behind the left sternocleidomastoid muscle. To exclude malignancy, a full workup, including clinical, radiological, and cytological examination, was performed but failed to provide a definitive diagnosis. Histological analysis following excisional biopsy revealed a benign epithelial cyst, consistent with an atypically located branchial cyst. We describe an approach to the management of these neck masses and discuss several theories of the etiology of branchial cysts and how they may come to be abnormally located.
A 66-year-old man was referred to our department with a 2-day history of a painless left cervical neck mass. He denied any other symptoms and reported that he only occasionally drank alcohol and had stopped smoking some 30 years ago with a total of 10 pack years. Clinical examination revealed a well-defined, painless neck lump, posterior to the sternocleidomastoid muscle close to the mastoid. The lump was some 5 centimeters in size, roughly oval, and not fixed to adjacent structures. There were no surrounding skin changes or other associated findings. Intraoral examination and transnasal fiber-endoscopy were normal. Cervical ultrasound showed an irregularly walled mass, 5 cm in diameter, with hyperechogenic reflections in an echo-poor center. The other neck structures were sonographically normal. Magnetic resonance imaging (MRI) showed a cystic lesion with an irregular wall lateral and posterior to the sternocleidomastoid muscle (neck level five; see Figures
Axial slides of T1-weighted MRI showing a hyperintense cystic lesion behind the left sternocleidomastoid muscle in the neck level five.
Axial slides of T2-weighted MRI showing a hyperintense cystic lesion behind the left sternocleidomastoid muscle in the neck level five.
In patients older than 40 years, especially with risk factors for malignant disease, it is prudent to consider all cystic lesions of the neck as malignant until proven otherwise. In patients younger than 40 years, clinicians should be aware of a metastasis of a papillary thyroid carcinoma [
In terms of malignant lesions, squamous cell carcinoma (SCC) of Waldeyer’s ring (e.g., palatine and lingual tonsils) and papillary thyroid cancers have a predilection for cystic lymph node metastases [
The aetiology of benign cervical cysts is also unclear. The most popular, but still controversial, theory is the branchial apparatus theory first described by Von Ascherson in 1832. Unfortunately, atypical locations of branchial cysts are poorly explained by this theory, and alternatives have been proposed such as the cervical sinus theory, the thymopharyngeal theory, and the inclusion theory [
Consequently, the thymopharyngeal theory indicates that lateral cervical cysts are a result of an incomplete obliteration of the thymopharyngeal duct [
Reporting a similar case to our own, Grignon et al. [
The diagnosis of a branchial cyst should—especially in patients older than 40 years—only be considered once malignancy has been excluded and should not be discounted because of an atypical location. Whilst in older patients metastatic SCC is more likely, in younger patients metastatic papillary thyroid cancer should be considered. Several theories exist as to the aetiology of branchial cyst formation, and some, such as the inclusion theory, are better able to explain abnormal locations.
The authors declare no conflict of interests.