Salivary Gland & Paranasal Sinuses Flashcards
Three major salivary glands
Parotid
Submandibular
Sublingual
Parotid gland anatomy
Are the largest of the salivary glands
Located behind the ramus of the mandible and covers the masseter muscle. Fills the space between the ramus and the anterior border of the sternocleidomastoid muscle.
Lymphatics of the parotid gland
Contain extensive lymphatic capillary plexus.
Lymphatics drain from laterally on the face, including eyelids, diagonally downward and posteriorly toward the parotid glands. As do the lymphatics from the frontal region of the scalp.
The parotid nodes then drain down along the retromandibular vein to empty into superficial lymphatics and nodes along the outer surface of the sternocleidomastoid muscle and into upper nodes on the deep cervical chain.
Lymphatics from the parietal region of the scalp also drain partly into the parotid nodes in front of the ear and the retro auricular nodes behind the ear before emptying into the upper deep cervical nodes.
Epidemiology of salivary gland tumours
Tumours of the salivary glands are rare and represent 3-4% of all cancers.
The parotid is the site with the highest incidence of salivary gland tumours (80-90%) and more than ⅔ are benign.
Tumours of the minor salivary glands represent 2-3% of these but are 65% are malignant.
Submandibular glands represent 10% of all these
Parotid gland tumours in children are much more likely to be malignant.
Malignant neoplasms occur in patients with an average age of 55
Benign tumours occur around age 40
The incidence in both genders is mostly equal with a slight male predominance
Etiology of salivary gland tumours
The cause is mostly unknown
Low-dose ionizing radiation in childhood may account for some cases of malignant tumours.
Females with a history of carcinoma in the salivary glands have eight times higher risk of breast cancer although the cause is unknown
Other risk factors may include dental radiographs
Clinical presentation salivary gland tumours
Presenting symptoms are localized swelling and pain
Facial palsy
Rapid growth
Radiation treatment of salivary gland tumours
Effective in cases of perineural involvement of nerves.
IMRT used sparing dose to the contralateral salivary gland, orbits, and brainstem.
The high-risk area can be treated with 200cGy/# and 180cGy/# can be treated to the surrounding area.
Pathology of salivary gland tumours
The most common cell types for malignant tumours are
Adenoid cystic
Mucoepidermoid
Adenocarcinoma
T1 stage salivary gland cancer
T1: Describes a small, noninvasive (has not spread) tumour that is 2 cm at its greatest dimension.
T2 stage salivary gland cancer
T2: Describes a larger, noninvasive tumour between 2 cm to 4 cm.
T3 stage Salivary gland cancer
T3: Describes a tumour that is larger than 4 cm but not larger than 6 cm and has spread beyond the salivary glands but does not affect the seventh nerve, the facial nerve that controls expression, such as smiles or frowns.
T4 stage salivary gland cancer
T4a: The tumour has invaded the skin, jawbone, ear canal, and/or facial nerve.
T4b: The tumour has invaded the skull base and/or the nearby bones and/or encases the arteries.
N1 stage salivary gland cancer
N1: Cancer has spread to a single lymph node on the same side as the primary tumour, and cancer found in the lymph node is 3 cm or smaller.
N2 stage salivary gland cancer
N2: Describes any of these conditions:
N2a: Cancer has spread to a single lymph node on the same side as the primary tumour and is larger than 3 cm but smaller than 6 cm.
N2b: Cancer has spread to more than 1 lymph node on the same side as the primary tumour, and none measures larger than 6 cm.
N2c: Cancer has spread to more than 1 lymph node on either side of the body, and none measures larger than 6 cm.
N3 stage salivary gland tumour
N3: Cancer found in the lymph nodes is larger than 6 cm.
Clinical presentation of the paranasal sinus cancer
History of sinusitis nasal obstructions and bloody discharge.
Tumours tend to invade the floor of the orbit causing eye displacement
Epidemiology of paranasal sinus cancer
Maxillary sinuses represent 80% of all sinus cancers.
2:1 male prevalence
Typical patients are older than 40
Etiology paranasal sinus cancer
Adenocarcinoma of the nasal cavity and ethmoid sinus is associated with wood dust exposure
SCC of the maxillary sinus and nasal cavity is associated with chemical agents found in nickel refining and leather tanning.
No association with smoking
Anatomy and physiology paranasal sinuses
The maxillary sinus is a pyramid-shaped cavity lined by ciliated epithelium bound by thin bone or membranous partitions.
The rough of the maxillary sinus is the floor of the orbit.
Radiation therapy for paranasal sinuses
IMRT allows for more conformal treatment and fewer long term side effects to the organs at risk than traditional methods.
Elective nodal irradiation is delivered to patients with T3/T4 SCC of the maxillary sinus
Standard fractionations:
High-risk PTV: 6600cGy in 220cGy/#
Standard risk PTV: 5400cGy to 6000cGy in 200cGy/#
Radiation can be used pre-op to create an easier resection for larger tumours
Radiation after surgery has the benefit of a full pathological review of all structures at risk.
Treatment volumes for paranasal sinus cancer
The nasal cavity, ethmoid sinuses and maxillary sinuses include both halves of the nasal cavity and the ipsilateral maxillary sinus.
Pathology of paranasal sinus cancers
SCC
T1 stage paranasal sinus
T1: tumour limited to maxillary sinus with no erosion or destruction of bone
T2 stage paranasal sinus
T2: tumour causing bone erosion or destruction including extension into the hard palate or middle nasal meatus, except extension to the posterior wall of the maxillary sinus
T3 stage paranasal sinuses
T3: tumour invades any of the following:
The bone of the posterior wall of the maxillary sinus
Subcutaneous tissue
Floor or medial wall of the orbit
Ethmoid sinuses
T4 stage paranasal sinus
T4a: moderately advanced local disease
Tumour invasive anterior orbital contents, the skin of the cheek, infratemporal fossa, cribriform plate, sphenoid or frontal sinus
T4b: very advanced local disease
Tumour invades the orbital apex, dura, brain, middle cranial fossa, cranial nerves or nasopharynx.
N1 stage paranasal sinus
N1: Unilateral metastasis in lymph nodes 6cm or less above the supraclavicular fossa, or unilateral or bilateral, retropharyngeal lymph nodes or less.
N2 stage paranasal sinuses
N2: Bilateral metastasis in lymph nodes, <6cm in the greatest dimension above supraclavicular fossa
N3 stage paranasal sinuses
lymph node >6cm in greatest dimension
