Salivary gland tumours epidemiology



Download 4.24 Mb.
Page1/2
Date22.04.2018
Size4.24 Mb.
  1   2
SALIVARY GLAND TUMOURS
EPIDEMIOLOGY



  • Primary neoplasms are uncommon

    • 3-5% of head and neck tumours

  • Salivary gland neoplasms most commonly appear in the sixth decade of life.

  • Patients with malignant lesions typically present after age 60 years, whereas those with benign lesions usually present when older than 40 years.

  • Benign neoplasms occur more frequently in women than in men, but malignant tumors are distributed equally between the sexes.

  • In children, 35% of salivary gland neoplasms are malignant. Hemangiomas are the most common benign tumor.

  • larger gland tumours are most common and most are benign tumours

  • Nearly 80% of these tumors occur in the parotid glands, 15% in the submandibular glands and the remaining 5% in the sublingual and minor salivary glands.

  • Benign neoplasms make up about 80% of parotid tumors, 50% of submandibular tumors and 10% of sublingual and 50% of minor salivary gland tumors.

  • palate is the most common site of minor salivary gland tumors

  • Most common benign major and minor salivary gland tumor is the pleomorphic adenoma, which comprises about 50% of all salivary gland tumors and 65% of parotid gland tumors

  • most common malignant parotid tumors in adults

  1. mucoepidermoid carcinoma (10% of all salivary gland neoplasms)

  2. adenoid cystic carcinoma

  3. malignant mixed tumor.

  • most common malignant parotid tumors in children:

  1. mucoepidermoid carcinoma

  2. acinic cell carcinoma

  3. undifferentiated carcinoma


AETIOLOGY

  • most unknown

  • associations:

    1. exposure to low dose ionizing radiation

    2. occupational exposure to rubber products manufacturing, asbestos mining, plumbing, and some types of woodworking

    3. smoking associated with Warthins tumor

  • 2 predominant theories:

    1. Bicellular stem cell theory

      • This theory holds that tumors arise from 1 of 2 undifferentiated stem cells, the excretory duct reserve cell or the intercalated duct reserve cell.

      • Excretory stem cells give rise to squamous cell and mucoepidermoid carcinomas

      • Intercalated stem cells give rise to pleomorphic adenomas, oncocytomas, adenoid cystic carcinomas, adenocarcinomas, and acinic cell carcinomas.

    2. Multicellular theory

      • each tumor type is associated with a specific differentiated cell of origin within the salivary gland unit.

      • Squamous cell carcinomas arise from excretory duct cells, oncocytomas arise from the striated duct cells, pleomorphic adenomas arise from the intercalated duct cells ,and acinic cell carcinomas originate from acinar cells.

      • Recent evidence suggests that the bicellular stem cell theory is the more probable etiology of salivary gland neoplasms. This theory more logically explains neoplasms that contain multiple discrete cell types, such as pleomorphic adenomas and Warthin tumors.


PREOPERATIVE EVALUATION

HISTORY


• progression

• pain - assoc with eating usually stone disease

• mass 81%

• pain 12%

• facial nerve paralysis 7%

• 50% Sx > 1yr


EXAMINATION

• externally

• oral cavity and oropharynx

• Warthin and Stensons ducts and orifices (flow, clarity, consistency, purulence, redness, bulging and irritation of the duct

• Tonsillar fossa and soft palate

• Bimanual palpation of all glands

• Comparison between sides

• Examination of neck



• Examination for other primaries that may have metastasized to the glands
PREOPERATIVE TESTS

  1. SIALOGRAPHY

    • seldom indicated for neoplastic conditions

    • good for assessment of strictures or calculi

    • only imaging modality that can diagnose early Sjogren’s Disease.

    • contraindicated in active infection and in patients allergic to contrast.

    • remain the most detailed way to image the ductal system.

    • calculi appear as a bubble in the duct

  2. CT SCAN

  • parotid tissue is more radiolucent than muscle but more dense than fat planes

  • extremely sensitive for the detection of a parotid mass

  • benign lesion appear smooth, round

  • malignant conditions lobulated, well outlined, infiltrative with poorly defined margins

  • assessment of cervical lymph nodes

  • one can infer the position of the facial nerve by locating the retromandibular vein and stylomastoid foramen

  1. MRI

    • adv over CT is no ionizing radiation, superior soft tissue detail

    • high grade malignancies tend to have a low signal on both T1 and T2 weighted images

    • benign lesions have low signal on T1 and high T2 signal

    • Can differentiate between pleomorphic adenoma vs Warthins vs malignancy

    • MRI is helpful in delineating the relationship between the tumour and the facial nerve and the involvement of the trigeminal nerve and intracranial invasion

    • MRA not as accurate as invasive angiography

    • delineates vascular anatomy and invasion of ICA




  1. NUCLEAR MEDICINE IMAGING




  1. ANGIOGRAPHY




  1. FNA

    • Overall sensitivity of FNAB in distinguishing between benign and malignant salivary gland tumors is approximately 95%. Its specificity is approximately 98%

    • Useful for nonneoplastic masses, metastases to parotid, non surgical lymphomas

    • usually ultrasound guided biopsy

    • FNA is important for preoperative planning and counselling, in high risk patients or secondary metastatic deposit is found

    • FNA for Warthin tumors can have false-positive results, leading to misdiagnosing more dangerous tumors such as pleomorphic adenomas and acinic cell carcinomas.

  2. CORE BIOPSY

  3. OPEN BIOPSY

    • Plan incisions

  4. FROZEN SECTION

    • helpful in diagnosing lymph node mets, tumour margins and perineural invasion


MANAGEMENT OF SALIVARY GLAND DISORDERS
GOALS

1.establish and confirm the diagnosis

2.eradication of the salivary pathology

3.preservation (or restoration) of function esp. the facial nerve
PROGNOSIS


  1. Tumor site

    • more favorable in major salivary glands

    • least favorable primary sites are the sublingual and minor salivary glands

  2. Histology.

  3. Grade (i.e., degree of malignancy).

  4. Extent of primary tumor (i.e., the stage).

  5. Whether the tumor involves the facial nerve, has fixation to the skin or deep structures, or has spread to lymph nodes or distant sites.


STAGING

  • Tumors arising in the minor salivary glands are staged according to the anatomic site of origin (e.g., oral cavity and sinuses).

  • clinical stage, particularly tumor size is probably more important than histologic grade


Primary tumor (T)

  • TX: Primary tumor cannot be assessed

  • T0: No evidence of primary tumor

  • T1: Tumor ≤2 cm in greatest dimension without extraparenchymal extension*

  • T2: Tumor >2 cm but ≤4 cm in greatest dimension without extraparenchymal extension*

  • T3: Tumor >4 cm and/or tumor having extraparenchymal extension*

  • T4a: Tumor invades skin, mandible, ear canal, and/or facial nerve

  • T4b: Tumor invades skull base and/or pterygoid plates and/or encases carotid artery

* [Note: Extraparenchymal extension is clinical or macroscopic evidence of invasion of soft tissues.

Regional lymph nodes (N)

  • NX: Regional lymph nodes cannot be assessed

  • N0: No regional lymph node metastasis

  • N1: Metastasis in a single ipsilateral lymph node, ≤3 cm in greatest dimension

  • N2: Metastasis in a single ipsilateral lymph node, >3 cm but ≤6 cm in greatest dimension, or in multiple ipsilateral lymph nodes, ≤6 cm in greatest dimension, or in bilateral or contralateral lymph nodes, ≤6 cm in greatest dimension

    • N2a: Metastasis in a single ipsilateral lymph node >3 cm but ≤6 cm in greatest dimension

    • N2b: Metastasis in multiple ipsilateral lymph nodes, ≤6 cm in greatest dimension

    • N2c: Metastasis in bilateral or contralateral lymph nodes, ≤6 cm in greatest dimension

  • N3: Metastasis in a lymph node >6 cm in greatest dimension

Distant metastasis (M)

  • MX: Distant metastasis cannot be assessed

  • M0: No distant metastasis

  • M1: Distant metastasis

AJCC stage groupings

Stage I

  • T1, N0, M0

Stage II

  • T2, N0, M0

Stage III

  • T3, N0, M0

  • T1, N1, M0

  • T2, N1, M0

  • T3, N1, M0

Stage IVA

  • T4a, N0, M0

  • T4a, N1, M0

  • T1, N2, M0

  • T2, N2, M0

  • T3, N2, M0

  • T4a, N2, M0

Stage IVB

  • T4b, any N, M0

  • Any T, N3, M0

Stage IVC

  • Any T, any N, M1

MANAGEMENT OF BENIGN TUMOURS

  • superficial parotidectomy for tumours of the superficial lobe

  • 25% extend to or involve the deep lobe - total parotidectomy with preservation of the nerve is indicated

  • recurrent tumours surgical resection ideally and consider adjuvant RTx

MANAGEMENT OF PAROTID NEOPLASIA

  • minimum therapy for low-grade malignancies of the superficial portion of the parotid gland is a superficial parotidectomy. For all other lesions, a total parotidectomy is often indicated.

  • Growing evidence suggests that postoperative radiation therapy augments surgical resection, particularly for the high-grade neoplasms, or when margins are close or involved

  • Clinical trials indicate that fast neutron-beam radiation improves disease-free and overall survival in patients with unresectable tumors or for patients with recurrent neoplasms.

  • surgical removal of the neoplastic material with a margin of normal tissue with preservation of nerve if at all possible

  • facial nerve preservation depends on a number of factors

    1. preoperative status of the nerve

    2. extent of the tumour and the location relative to the nerve

    3. histologic type

    4. perineural spread

    5. radiosensitivity of the tumour

  • as long as nerve is not infiltrated then preservation is possible

  • Perineural invasion can also occur, particularly in high-grade adenoid cystic carcinoma, and should be specifically identified and treated.

  • Indications for facial nerve sacrifice

  1. nerve involvement

  2. adenoid cystic and to a lesser degree SCC

  • Radiation therapy may increase the chance of local control and increase the survival of patients when adequate margins cannot be achieved.

  • Unresectable or recurrent tumors may respond to chemotherapy.

  • Fast neutron-beam radiation therapy or accelerated hyperfractionated photon-beam schedules have been shown to be effective in the treatment of inoperable, unresectable, and recurrent tumors.

Stage I Major Salivary Gland Cancer

  • Low-grade tumors

  1. Surgery alone – usually curable

  2. Postoperative radiation therapy should be considered when the resection margins are positive.

  1. High-grade tumors

  1. Localized high-grade salivary gland tumors that are confined to the gland in which they arise may be cured by radical surgery alone.

  2. Postoperative radiation therapy may improve local control and increase survival rates for patients with high-grade tumors, positive surgical margins, or perineural invasion


Stage II/III Major Salivary Gland Cancer
Low-grade tumors

  1. Surgery alone or with postoperative radiation therapy, if indicated.

  2. Chemotherapy should be considered in special circumstances, such as when radiation therapy or surgery are refused.

High-grade tumors



  1. Localized high-grade salivary gland tumors that are confined to the gland in which they arise may be cured by radical surgery alone.

  2. Postoperative radiation therapy may improve local control and increase survival rates for patients with high-grade tumors, positive surgical margins, or perineural invasion.[Level of evidence: 3iii]

  3. Fast neutron-beam radiation or accelerated hyperfractionated photon beam schedules reportedly are more effective than conventional x-ray therapy in the treatment of inoperable, unresectable, or recurrent malignant salivary gland tumors.


Stage IV Major Salivary Gland Cancer/ Recurrent cancer

  1. Not curable with surgery

  2. Fast neutron-beam radiation or accelerated hyperfractionated photon beam schedules have been reported to be more effective than conventional x-ray therapy in the treatment of inoperable, unresectable, or recurrent malignant salivary gland tumors

Low Grade tumors



  1. acinic cell tumour

  2. low-grade adenocarcinoma

  3. low-or-intermediate grade mucoepidermoid carcinoma

high grade



  1. high-grade mucoepidermoid

  2. SCC

  3. undifferentiated carcinoma

  4. carcinoma ex pleomorphic adenoma

  5. high-grade adenocarcinoma

  6. adenoid cystic carcinoma


MANAGEMENT OF REGIONAL LYMPH NODES IN SALIVARY GLAND MALIGNANCIES


  • Any N+ neck needs comprehensive neck dissection

  • clinically negative neck is more controversial

options

    1. close observation

    2. modified radical selective neck dissection

    3. radiotherapy



Indications

  • high grade tumours

  • perineural invasion

  • tumours with high risk of subclinical lymph node spread

    1. T3 and T4 lesions

    2. SCC

    3. high grade mucoepidermoid carcinoma

    4. carcinoma ex pleomorphic adenoma

    5. high grade adenocarcinoma

RTx is effective for improving local control



indications for post-operative RTx

  • positive surgical margins

  • cancer close to surgical margins

  • high grade malignancy ( as above)

  • perineural spread

  • presence of cervical metastatic disease

  • recurrent cancer

  • locally extensive cancers


RTx should not be used as primary therapy for surgically resectable tumours


PATHOPHYSIOLOGY
NONNEOPLASTIC CONDITIONS


  1. Infections

    1. Acute/chronic sialadenitis

  2. Inflammatory

    1. Autoimmune sialadenitis

    2. Sarcoidosis

  3. Calculi

    1. Sialolithiasis

    2. mucocysts

  4. Systemic illness

    1. sialoadenosis

  5. Vascular

    1. Necrotising sialometaplasia



SIALOADENOSIS

  • nonneoplastic noninflammatory swelling in association with acinar hypertrophy and ductal atrophy.

  • nontender swelling that is often bilateral and symmetric but can be unilateral and asymmetric.

  • Etiologies fall into 5 major categories.

  1. Nutritional (eg, vitamin deficiency, bulimia)

  2. Endocrine (eg, diabetes mellitus, hypothyroidism)

  3. Metabolic (eg, obesity, cirrhosis, malabsorption)

  4. Inflammatory/autoimmune (eg Sjögren disease, Heerfordt syndrome)

  5. Drug induced (eg, thiourea)


ACUTE SIALADENITIS

  • bacterial infections are usually associated with ductal obstruction

  • most common bacterial pathogens are staph. aureus, strep viridans, B-haemolytic strep and pneumococcus

  • may develop submandibular abscess, spread to involve other deep neck spaces of the neck. Trismus may be indicative of parapharyngeal involvement.

  • Viral infections less common - coxsackievirus, parainfluenza, cytomegalovirus, echovirus, HIV

  • Mumps can affect one or both parotids and the other salivary glands

  • recurrent attacks cause atrophy, fibrosis, strictures


CHRONIC SIALADENITIS

  • typically less painful and is associated with recurrent enlargement of the gland (often following meals) typically without erythema.

  • Associated with conditions linked to decreased salivary flow, rather than dehydration

  • These conditions include calculi, salivary stasis, and a change in the fluid and electrolyte composition of the gland.


SIALOLITHIASIS

  • 80% submandibular and are usually radioopaque

  • 20% parotid and radiolucent

  • present with a colicky postprandial swelling of the gland

  • typically composed of calcium phosphate or calcium carbonate

  • mechanism of stone formation:

  1. Salivary stagnation

  2. Epithelial injury along the duct resulting in sialolith formation, which acts as a nidus for further stone formation

  3. Precipitation of calcium salts



CONGENITAL DISORDERS

absence of the parotid and facial n in 1st and 2nd branchial arch syndromes



herterotopic salivary gland tissue and sinuses
TRAUMA
MUCOCELES

  • Mucocele

    • pseudocysts resulting from ductal rupture and localized extravasation of minor salivary glands

    • may also occur due to partial or total excretory duct obstruction leading to acinar rupture due to intraluminal hypertension



  • Ranulas (Rana = frog belly), which involve the major salivary glands, are divided into 2 types

  1. Oral ranulas - secondary to mucus extravasation that pools superior to the mylohyoid muscle - large unilateral blue to translucent mass in the floor of the mouth

  2. Cervical ranulas (deep plunging) are associated with mucus extravasation along the fascial planes of the neck – almost always due to ranula of the sublingual gland

  • Histologically, ranulas lack an epithelial lining and instead are lined by a condensed fibrous connective tissue wall that is infiltrated by inflammatory cells



  • CT - mucus content is homogeneous and its density, as seen on a CT scan, is much less than surrounding muscle tissue. Also diagnostic tail that can be used to trace it from the sublingual gland in the sublingual space to the submandibular space.


  1   2


The database is protected by copyright ©dentisty.org 2019
send message

    Main page