Cervical ultrasound pitfall

A 23-year-old female without relevant medical history. A cervical ultrasound was performed to rule out goiter.

A hypoechogenic well defined structure with striated appearance was demonstrated on grey-scale ultrasound with small air foci inside the lesion. The submandibular gland and mylohyoid muscle are unremarkable.

The palatine tonsils are part of the Waldeyer´s ring, lymphoid tissue located in the nasopharynx and oropharynx [1, 2, 3]. The Waldeyer´s ring is especially important in the pediatric population since they have more tendency to suffer from infectious or inflammatory processes [1]. When bigger than normal, they may be a cause of sleep apnea [1].

Ultrasound is an excellent imaging technique in the neck exploration of pediatric and young population because of its availability, the fact that it is a noninvasive technique and the lack of ionizing radiation, ionidated intravenous contrast or sedation necessity [1, 2, 3, 4].

On ultrasound a palatine tonsil is seen as a hypoechogenic well-circumscribed lesion [1,3-5] with a typical internal striated appearance. It is in the pharyngeal mucosal space, deep to the submandibular gland and the mylohyoid muscle [2, 3]. The characteristic internal striated appearance with alternating hypo- and hyperechogenic linear bands is due to the presence of tonsillar crypts [1 - 4]. Inside the crypts, small air foci can be also seen [2, 3].

When an inflammatory process is developing, such as tonsillar cellulitis or abscess, the striated appearance disappears [1]. In tonsillar cellulitis an enlarged tonsil with obscured borders may be visualized, while abscess is defined by an anechogenic cystic lesion inside the tonsil or in the paratonsillar tissue [2, 3, 5].

There are no differences in size between males and females [4] and there are also no commonly accepted normal values for the dimension of the palatine tonsils. Maximum size is usually during puberty [1- 4], up to 2 cm in longitudinal dimension [2, 3, 5].

Knowledge of the normal ultrasound characteristics and features of the palatine tonsil is mandatory for radiologists in order to avoid misdiagnosis [2, 3].