![]() ![]() More attention is being paid to ipsilateral and contralateral medial retropharyngeal lymph node during oncologic staging, as all lymphatic drainage of the head appears to pass through these nodes. The lateral retropharyngeal lymph node is small (less than 1 centimeter) and circular, and lies at the dorsal border of the mandibular salivary gland and beneath the caudal portion of the parotid gland. In approximately 33 percent of dogs, a lateral retropharyngeal node is present. In approximately 21 percent of dogs, two medial retropharyngeal nodes are present ipsilaterally. Figure 2: A single-incision approach as been described for removal of parotid, mandibular and medial retropharyngeal lymph nodes.5 A cadaver specimen shows the common lymph nodes and salivary glands of the neck. Care must be taken to avoid the structures medial to the node, including the common carotid artery, internal jugular vein, hypoglossal nerve, vagus nerve, and sympathetic trunk. It lies under the wing of the atlas in the triangle bounded by the digastricus cranially, musculus longus colli dorsally, and the larynx ventrally. It’s a long (approximately 5 centimeters in a large dog), relatively thin (approximately 2 centimeters in a large dog) node that sits caudal and medial to the mandibular salivary gland, just ventromedial to the brachiocephalicus and sternocephalicus muscles. The medial retropharyngeal node is the largest lymph node of the head. The parotid lymph node is about the size of a pea and sits rostral to the parotid salivary gland. The mandibular salivary gland is larger, softer, more caudal, deeper, and less freely movable than mandibular lymph nodes. ![]() When first developing the skills to palpate the neck, it can be difficult to distinguish the mandibular lymph node from the mandibular salivary gland. They can feel larger if two nodes are very close together or if the nodes truly are enlarged due to reactive or effaced nodes. In dogs, depending on patient size, the nodes range between the size of a black bean and a kidney bean. In cats, the mandibular lymph nodes are about the size of a small pea. The nodes normally are smaller and firm compared to the larger and more pliable mandibular salivary gland. The mandibular lymphocentrum (not submandibular, as referred to in humans) consists of one to five nodes that are nestled between the bifurcation of where the lingual and facial veins branch from the linguofacial vein, rostral and lateral to the mandibular salivary gland. There are three commonly described lymphocentrums of the head and neck. Therefore, rather than referring to a mandibular lymph node, for example, we refer to a mandibular lymphocentrum, which describes the region containing mandibular lymph nodes on one side of the body. Though we think of lymph nodes as being consistent from one animal to another, in reality, there is variation in number. These nodes also may be enlarged in cases of lymphoma. Careful aspiration, with particular attention to avoiding trauma to the eye if aspirating in an awake patient, can confirm the diagnosis of lymphoid hyperplasia or normal lymph node. These can be a normal finding in any dog, but they are easier to see and palpate in young, large-breed dogs with short hair. Their appearance, bilateral symmetry, and signalment suggested the most likely differential diagnosis to be buccal ( a.k.a. ![]() These swellings were well circumscribed and freely movable beneath the skin. Recently, a young Weimaraner presented for eyelid surgery through our ophthalmology department, and it was noticed that he had bilaterally symmetrical subcutaneous soft tissue swellings dorsal to the maxillary third premolar teeth (Figure 1). By John Lewis, VMD, FAVD, DAVDC Figure 1: A young Weinmaraner was presented with bilateral, freely movable subcutaneous swellings. ![]()
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