Chapter 17. Neck Swellings/Lumps: Midline Neck Swellings 173
FIGURE 17.1. Thyroglossal cyst in the midline.
17.2.2 Midline Dermoid Cyst
These are developmental abnormalities caused by abnormalities in midline fusion in the fetus. They appear clinically as midline lesions occurring at any level in the neck. They do not move on tongue protrusion.
17.2.3 Lymph Nodes
While lymphadenopathy in the neck is most commonly situated laterally, submental nodes especially may present in the midline.
17.2.4 Thyroid Nodule
Pyramidal lobe nodules or those occurring in the thyroid isthmus may present as a midline lump, although thyroid nodules occur most commonly laterally in the neck.
17.2.5 “Plunging” Ranula
A ranula is an extravasation pseudocyst caused by obstruction of a minor salivary gland in the floor of the mouth.
174 Neil Bateman
FIGURE 17.2. Ranula in the floor of the mouth.
Typically they present as a easily recognizable lesion in the mouth (Fig. 17.2). A “plunging” ranula is one which has become so large as to present in the neck. The diagnosis is usually apparent on intra-oral examination.
17.2.6 Investigations
In most children a presumptive clinical diagnosis can be confirmed with ultrasound. This can differentiate between cystic and solid lesions. While ultrasound is a highly user dependant modality it is often possible to positively identify lymph nodes using it as well as other common lumps such as lipomata. In the case of thyroglossal duct cysts ultrasound is also used to identify the presence of a normal thyroid gland. Occasionally other imaging modalities such as MRI can be helpful although these are more commonly used in larger, more complex neck masses.
Fine needle aspiration, while in adults the investigation of choice for many neck lumps, is very rarely helpful in investigating neck lumps in children.