OP 8 part 2.. M. Abukar

by Mohammad Abukar 4/12/2011, 2:03 am

http://www.mediafire.com/?sfn24to1t5jsfv4

Here is the second part of my sheet...

My laptop went down so I wrote this sheet in an internet café.. so.. I didn't spend that time on it.. so.. sorry for any mistake.. and surely thanks for Suhaib who sent me the record once more and gave me a valuable information :)

by Mohammad Abukar 4/12/2011, 2:04 am

Oral Pathology sheet #8-part 2

Salivary gland tumors:

Uncommon (2% of all tumors of head and neck) 1:6????
More common in females > 5^th decade of life.
80% of these tumors occur in major salivary glands, 20% in minor ones.
Tumors of major salivary glands occur mainly in parotid (90%) then in submandibular (10%), they are rare in the sublingual salivary gland.

So, 70% of all salivary glands tumors occur in parotid gland (90% of the 80%).
Minor salivary glands tumors occur mainly in the palate (55%) then in the upper lip.
other sites of minor salivary glands (e.g. lower lip and buccal mucosa) count only for 25% of all minor salivary glands tumors.

Of parotid gland tumors only 15% are malignant (85% benign).
Of submandibular gland tumors 30% are malignant and 70% are benign (so almost one third of its tumors are malignant).
Sublingual gland tumors carry a high risk of malignancy (85%).
Of minor salivary glands tumors 50% are malignant and 50% are benign so the risk of malignancy in the minor salivary glands is high in comparison to parotid and submandibular salivary glands.

Classification of salivary glands tumors:

Benign or malignant
Benign tumors are called adenomas; they grow slowly and need years to appear clinically, they are soft or rubbery upon palpation, there is no ulceration of skin or mucus membranes above the tumor and there is no damage to the sensory or motor neurons near the tumor. (e.g. Pleomorphic adenomas and Warthin tumor)

Malignant tumors are called adenocarcinomas; they grow rapidly, hard upon palpation, ulceration to or destruction of skin or mucus membranes may take place, nearby nerves may be affected so anesthesia or paresthesia may occur if a sensory nerve was affected and paralysis may occur if the affected nerve was motor. (e.g. mucoepidermoid carcinoma).

Benign tumors of the salivary glands:

Pleomorphic adenoma:

Its name (pleomorphic) may suggest malignancy but the name is incorrect as "pleomorphic" here does not indicate malignancy but indicates that the tumor shows many variations in microscopically. Thus, pleomorphic adenomas are not similar to one another even in the same patient different histopathological features may be seen.

It is also called a mixed tumor; this does not mean that the tumor has many origins (ectoderm and endoderm for example as it is originated from myoepithelial cells) but indicates the variations (connective tissue stroma and myoepithelial cells).

Pleomorphic adenoma is a common salivary gland tumor (85% of all salivary gland tumors)
84% of pleomorphic adenomas are found in parotid gland.
Pleomorphic adenoma counts for 70% of parotid tumors (80% arises from the superficial lobe of parotid not the deep one). SO, they are mainly found in the superficial lobe of parotid gland.
8% of them are found in submandibular gland = 50% of submandibular gland tumors.

Clinically, it can be seen as a swelling around the ramus and angle of the mandible.
It is benign, well defined, painless, slowly growing, has rubbery swelling and sometimes it is lobulated and it may recur.. the last two features can be explained by histopathology.
The lobules are not more than one tumor especially if left for long time r recurred after surgical removal.

Pleomorphic adenoma counts for 45% of minor salivary gland tumors (almost the half) and as previously mentioned most of minor salivary gland tumors occur in the palate. So, when a dentist sees a swelling in the palate he should consider pleomorphic adenoma OR abscess from teeth.. you should have a differential diagnosis.

Histologically:

Extensive variations (pleomorphic) as it has epithelial components and connective tissue stroma (mixed)

It is capsulated BUT the capsule may be deficient or very thin and this is the reason of the appearance of lobules.. so this is not invasion but extension because of deficient capsule. As a result, the surgeon should remove a safety margin and this explains the local recurrence.

Epithelial cells:
* Epithelial duct cells (make duct-like spaces)
* Myoepithelial cells (may arrange in sheets or strands or clumps like islands)

Myoepithelial cells may become similar to plasma cells and are called plasmacytoids.. some may undergo metaplasia and become squamous cells and starts to produce keratin.

What characterizes the pleomorphic adenoma is that there is abundant stroma.
The stroma shows variations: fibrous, chondroid as it undergoes hyalinization (amorphous eosinophilic material is seen) or myxoid (mucus around the epithelium cells).. All these types may be seen in the same tumor.

If mucoid then expect a higher recurrence rate than chondroid or fibrous because the capsule may rupture and the neoplastic cells may spread as a result.. if fibrous or chondroid there will be no rupture or recurrence.

Warthin tumor: (also called Adenolymphoma and papillary cystadenoma lymphomatosum)

Implantation of salivary gland duct epithelium inside lymphoid tissue inside lymph nodes that are around the parotid gland.
During development, implantation of salivary gland ductal epithelium in the lymph nodes of parotid then proliferation of these salivary gland tissues inside the lymph nodes may occur and results in the development of Warthin tumor.

Warthin tumor is also called adenolymphoma which is not a correct name because of the word lymphoma that indicates malignancy.

Clinically, it is almost exclusive for parotid gland (9% of all parotid gland tumors). It was thought to be more common in males but it became more common in females as it is associated with smoking (eightfold increased risk) and as females are now smoking more than before.

One important thing about this tumor is that it is bilateral involving both glands which is uncommon for a tumor.. the two tumors may not be simultaneous. The patient may suffer the second tumor years after the previous one on the other side.

It may be multiple in the same gland (more than one focus). Warthin tumor occurs mostly in the TAIL of parotid gland so you see a swelling around the patient's angle of the mandible.. usually parotid tumors are anterior to the ear but this one is seen at the angle of the mandible.

Grossly, you see cystic spaces (contrary to pleomorphic adenoma where there is n cystic spaces and is a solid tumor).. these cystic spaces are filled with mucoid material and you see papillary projections at the walls thus it is also called papillary cystadenoma lymphomatosum (because it contains cystic spaces with papillary projections and lymphatic tissue)

With magnification, papillary projections lined with epithelial cells and their stroma is NORMAL lymphoid tissue (like lymph nodes inside it there is a proliferation of epithelium and making a cystic space).. the lymph node is normal.. it is NOT a part of the tumor so inside it you see active germinal centres that are not neoplasms.

Papillary projections are double-layered (columnar and cuboidal cells).. The superficial layer is columnar and the basal layer is cuboidal.. they have marked eosinophilic granules and they are called oncocytes (have eosinophilic cytoplasm with granules).

You have to read about basal cell adenoma.

Oncocytoma is another salivary gland tumor that you should read about.. it may be bilateral (like Warthin tumor).. you should know why it is called oncocytoma.

Another benign salivary gland tumor is canalicular adenoma.. it is almost always in the upper lip.. we said that most minor salivary gland tumors occur on the palate but this tumor occurs mainly in the upper lip.

Why canalicular? Because its histopathology looks like canals..
one important thing about this tumor is that it may show cell degeneration resulting in cystic spaces and so you see the neoplastic tissue only at the peripheries and lots of degeneration.. so you may be thinking of a cyst in the upper lip but it is canalicular adenoma.

Ductal papilloma is a rare benign tumor.. ductal à from ducts.. papilloma à looks like squamous cell papilloma.. so it grows like a papilloma inside the duct so it will cause obstruction and you may think it is a stone but it is a tumor.. so it is a proliferation of lining epithelial duct cells making papilloma inside the duct and causing signs of obstruction to appear clinically.

Malignant tumors of the salivary glands:

Mucoepidermoid carcinoma:

It is the commonest malignant salivary gland tumor and forms 10% of all salivary gland tumors.. mainly in old people.. 50% occurs in parotid, 20% in the palate. It counts for 10-15% of all minor salivary glands.

It is NOT the most common malignant salivary gland tumor in minor salivary glands.. it is the most common overall and the most common of major salivary glands while the most common malignant tumor of minor salivary glands is Adenoid cystic carcinoma.

It is adenocarcinoma.. but in some cases you may think it is pleomorphic adenoma as it still did not cause ulceration, anesthesia or paresthesia of the palate for example so you think of pleomorphic adenoma.. The patient may come with signs of malignancy such as ulceration, destruction, paralysis of the lip, etc.

Histologically:

There are low grade and high grade types of this tumor.

There is no capsule so invasion in all directions take place so it is hard to know where its margin is so the whole gland should be removed…

With magnification there are three types of cells: Mucus, squamous (thus called muco+epidermoid) and intermediate cells.

Intermdiate cells are not squamos or mucus but may transform to any.. these cells can be arranged in nests, diffuse sheets and you can see cystic spaces in some places.

Cystic spaces contain mucus and lined by mucoid cells and around them are the epithelial cells (squamous cells) and there is a supporting stroma.

With magnification you can notice high or low grade tumors….

Low grade à mucus cells are dominant and there are cystic spaces filled with mucus and epithelial (squamous cells) and shows no signs of malignancy.. the low grade one is the one that may be misthought to be pleomorphic adenoma.

Local recurrence rate (LRR) = 10% only
5 year survival = 95%

High grade à destruction, ulceration, invasion and nerve problems.. you don't see mucus cells or cystic spaces.. you may need special stains like PAS to look for mucus cells as they are not the majority of cells.. the majority of cells are undifferentiated so you need markers to prove that these are salivary glands epithelial cells.. so… no mucus or cystic spaces.. and there are signs of malignancy like peomorphism and high mitotic activity.

LRR = 80%
5-year survival = 30% only

Acinic cell carcinoma: another malignant tumor of salivary glands.

Adenoid cystic carcinoma:

It is the second most common malignant tumor of salivary glands in general and the most common one in minor salivary glands.

It counts for 30% of minor salivary gland tumors.. so in minor salivary glands 45% pleomorphic adenoma and 30% adenoid cystic carcinoma.. the remaining 25% is for all other tumors.

It counts for 3-6% of parotid tumors

Clinically it may look like pleomorphic adenoma but usually it causes ulceration, destruction, pain and facial paralysis if it is in parotid.. if in palate it may cause paresthesia in the palate.. the area affected is what determines whether paresthesia or anesthesia will occur..

Histologically:

It is called adenoid cystic then there are cystic spaces..
There are three patterns of it: cribriform, tubular and solid.

Cribriform pattern: neoplastic epithelium arranged as ovoid or irregularly shaped islands or as anastomosing strands lying in a scanty connective tissue stroma.. the characteristic feature of this tumor is the presence of numerous microscopic cyst-like spaces within the epithelial cells producing a cribriform, lace-like or swiss-cheese appearance.

Another thing that may be characteristic is that the tumor cells have tendency to surround nerves along their path and this increases the recurrence rate as the surgeon may leave a part of the tumor but leave the area around the nerve..

This characteristic of this tumor is called "neurotropism".. as if this tumor loves nerves or the lymphoid spaces around them..

Tubular pattern

Solid pattern: There is no cystic spaces (it is solid)..
The less the spaces the poorer the prognosis.. so the solid pattern has the highest LRR and is the most to cause death of the 3 patterns.

Prognosis: it may spread around nerves and may spread in marrow spaces without making destruction of bone s it is difficult to control and may spread in the skull and so it is difficult to get rid of by surgery so it has a poor prognosis…

5 year survival: 75%
10 year survival: 40%
20 year survival: 20%

So recurrence may occur even after 15 years as it may spread in marrow spaces around the nerve so these patients need a lifelong follow up because local recurrence may occur at any time especially if it was of the solid pattern histopathologically.. However, cribriform pattern is the most common one.

Carcinoma expleomorphic adenoma:

The name indicates that this tumor was a pleomorphic adenoma then it transformed to be now a carcinoma. This happens in 2-4% of pleomorphic adenomas. It happens in pleomorphic adenomas that were left untreated for 10-15 years or that recurred after surgical removal.

Histologically:

It may transform to any type (mucoepidermoid, adenoid cystic, squamous or any other carcinoma)

Prognosis depends whether the malignancy penetrated the capsule or not.. if yet then it will have a good prognosis.. if it did then it will have a poor prognosis.

Read about polymorphuos low-grade adenocarcinoma and know why we called them as such? They are called low-grade because metastasis to regional lymph nodes occurs in 6-10% of cases. They are called polymorphous because of the variations that may be seen histologically which remind us about pleomorphic adenoma.

Other malignancies (even squamous cell carcinoma can occur inside the parotid gland

The rule is that most salivary gland tumors are benign, in the superficial lobe of parotid gland.

Focus on pleomorphic adenoma, mucoepidermoid carcinoma, adenoid cystic.. and Warthin to some extent because there are some unique features for it.

*My laptop went down so I wrote this sheet in an internet café.. so.. I didn't spend that time on it.. so.. sorry for any mistake.. and surely thanks for Suhaib Attieh who sent me the record once more and gave me a valuable information J

By: Mohammad M. Abukar

OP 8 part 2.. M. Abukar

OP 8 part 2.. M. Abukar

Re: OP 8 part 2.. M. Abukar