Path Chapter 16: Head and Neck
Oral cavity:
- Teeth are surrounded by gingival mucosa – page 740
- The crown of the tooth projects into the mouth, and is covered by enamel, which is hard acellular tissue, and the most highly mineralized tissue in the body
- Enamel sits on dentin, which is a specialized form of connective tissue that makes up most of the remaining hard part of the tooth
o Dentin is cellular and has many dentinal tubules, which have cytoplasmic extensions of odontoblasts
o Odontoblasts line the meeting of the dentin and pulp, and can make new (secondary) dentin when stimulated
- The pulp chamber is surrounded by the dentin and has stroma rich in nerve bundles, lymphatics, and capillaries
- Teeth are attached to the jaws by the periodontal ligament, which provides a strong but flexible attachment that can withstand the forces of chewing
o The periodontal ligament attaches to the jaw bone on one side, and the cementum at the roots of the teeth on the other side
§ Cementum acts like cement to attach the teeth to the periodontal ligament
- Dental caries (tooth decay) – localized degradation of the tooth
o The most common cause of tooth loss before age 35
o Caries happen from the tooth mineral getting dissolved by acidic metabolic products from bacteria in the oral cavity, from metabolizing sugars
o Fluoride prevents caries by incorporating into the crystalline structure of the enamel, forming fluorapatite, and adds to the resistance to degradation by bacterial acids
- Gingiva – squamous mucosa in between the teeth and around them
- Gingivitis – inflammation of the gingival mucosa and associated soft tissues
o Gingivitis develops from lack of proper oral hygiene, causing accumulation of dental plaque and calculus
o Dental plaque – sticky, colorless biofilm that builds on teeth, formed by oral bacteria, proteins from saliva, and desquamated epithelial cells
o If plaque continues to build and isn’t removed, it becomes mineralized to form calculus (tartar)
o The bacteria in the plaque release acids from sugar-rich foods, which erode the enamel surface of the tooth, and when this happens chronically it leads to caries (tooth decay)
o Plaque build-up beneath the gumline can cause gingivitis
o Chronic gingivitis is characterized by gingival erythema, edema, bleeding, and loss of soft-tissue adaptation to teeth
o Gingivitis happens at any age, but is most common and severe in adolescence
o Gingivitis is reversible, and you fix it by decreasing accumulation of plaque and calculus through brushing and flossing
- Periodontitis – inflammation of the supporting structures of the teeth, including the periodontal ligaments, alveolar bone, and cementum
o If untreated, periodontitis can progress and cause loss of attachment from destruction of the periodontal ligament and alveolar bone
§ This can loosen and cause loss of teeth
o Periodontitis is caused by bad bacteria causing too many bad effects at these sites
§ Healthy bacteria are usually gram positives, while the periodontitis-causing bacteria are usually gram negative
§ The main causes of periodontitis are aggregatibacter (actinobacillus) actinomycetemcomitans, porhyromonas gingivalis, and prevotella intermedia
o Periodontitis usually presents by itself, but it can also be part of AIDS, leukemia, Chrohn’s, diabetes, Down syndrome, sarcoidosis, and neutrophil problems
o Organisms from periodontitis can also turn systemic and cause endocarditis & abscesses
- Reactive soft tissue nodules of the oral cavity are common
o The most common fibrous proliferative lesions of the oral cavity are fibromas and granulomas
o Irritation fibromas happen mainly in the buccal mucosa at the bite line or where the gingiva meets the teeth – page 741 top pic
§ An irritation fibroma is a raised nodule of fibrous tissue in the mouth, that you treat by excising it
o A pyogenic granuloma is a very vascular lesion usually in the gingiva of kids, teens, and pregnant women (aka pregnancy tumor) – page 741 bottom pic
§ The surface is ulcerated and looks bright red/purple
§ Growth can be very rapid, with lots of vascular proliferation
§ They can regress after pregnancy, turn fibrous, or turn into a peripheral ossifying fibroma
§ You treat a pyogenic granuloma by excising it
o A peripheral ossifying fibroma is a common reactive growth of the gingiva, that looks like a red, ulcerated nodule
§ They tend to recur, so you have to excise down ot the periosteum to remove it
o Peripheral giant cell granuloma is a common lesion of the gingiva, covered by intact gingival mucosa usually, that looks more blue/purple, and is made of giant cells
- Apthous ulcers (canker sores) – extremely common superficial ulcers of the oral mucosa that affect almost half of people
o They’re more common in people 20 or younger, very painful, and often recurrent
o Canker sores tend to be more prevalent in certain families
o Canker sores are shallow, hyperemic ulcers covered with a thin exudate and rimmed by a zone of erythema – page 742
o They can spontaneously resolve within 10 days, or last weeks
- Glossitis – inflammation of the tongue, usually referring to the “beefy-red” tongue seen in certain deficiencies
o Glossitis happens from atrophy of the papillae of the tongue and thinning of the mucosa, exposing the underlying vasculature
o The atrophic changes can sometimes lead to inflammation and shallow ulcers
o Glossitis can happen in B vitamin deficiencies, & also in sprue & iron-deficiency anemia
o Plummer-Vinson-Paterson-Kelly syndrome – combo of iron deficiency anemia, glossitis, and dysphagia, with webs
o Glossitis with ulcers can also happen from teeth, bad dentures, syphilis, or inhaling or ingesting chemicals
- Infections of the oral cavity:
o Oral mucosa is very resistant to its normal flora
o Oral defenses include competitive suppression by native organisms, secretory IgA, antibacterials in saliva, and irrigating effects of food or drink
o Immunodeficiency and antibiotics are 2 things that can mess up this oral defense
o Herpes simplex virus (HSV) – most orofacial HSV is HSV-1
§ Oral sexual habits though can let HSV-2 get on the face
§ Primary HSV infection usually happens in kids 2-4 years old, is often asymptomatic, and doesn’t cause much problem
§ Up to 1/5 of the time, primary HSV infection presents as acute herpetic gingivostomatitis, with abrupt onset of blisters and ulcers throughout the oral cavity, especially in the gingiva, along with swollen lymph nodes and fever
§ The blisters start filled with a clear serous fluid, that often rupture to form a very painful red-rimmed shallow ulcer
§ You may see intranuclear viral inclusions, or cells may fuse into giant cells
§ You can diagnose with a Tzanck test that looks at the blister fluid under a microscope
§ The blisters go away within 3-4 weeks, but the virus gets into regional nerves and eventually becomes dormant in the local trigeminal ganglia
§ Most adults have HSV-1, but only a minority have the virus reactivate to form a cold sore, usually in young adults
§ Things that can reactivate include trauma, allergies, exposure to UV light, upper respiratory infection, pregnancy, menstruation, immunosuppression, and exposure to extreme temperatures
§ Recurrent herpetic stomatitis happens either at the primary site of inoculation, or in nearby mucosa of the same ganglion
· It looks like groups of small blisters, that dry up in 4-6 days and heal within 10
· The most common sites for recurrent HSV is the lips (herpes labialis) nasal orifices, buccal mucosa, gingiva, and hard palate
o Oral candidiasis (thrush) – most common fungal infection of the oral cavity
§ Candida albicans is part of the normal oral flora in half of people
§ Pseudo-membranous (thrush) is the most common form of oral candidiasis
§ Oral candidiasis looks like curd-like gray/white inflammation made of organism and exudate, that can be scraped off
§ Thrush only causes problems in immunosuppressed people, like in diabetes, antibiotic use, AIDS, etc.
o Page 744 – table of when oral lesions are signs of systemic disease
o Hairy leukoplakia – oral lesion that is white, merging patches of fluffy (“hairy”) hyperkeratotic thickenings, almost always found on the lateral border of the tongue
§ 4/5 of people with hairy leukoplakia have HIV
§ The other 1/5 happen from other causes of immunosuppression, like cancer therapy or transplant immunosuppression
§ Unlike thrush, hair leukoplakia can’t be scraped off
§ Under microscope, hairy leukoplakia characteristically shows hyperparakeratosis & acanthosis w/ “balloon cells” in the upper spinous layer
§ Sometimes there is koilocytosis of the superficial, nucleated epidermal cells, suggesting HPV, but it can also be EBV
§ In hairy leukoplakia from HIV, AIDS symptoms show up within 2-3 years
- Oral cancers are common worldwide, and have a fairly high mortality
- Leukoplakia – white patch or plaque that can’t be scraped off and can’t be characterized as any other disease, so basically if a white lesion can be diagnosed anything else, it’s not leukoplakia, otherwise it is, so they’re there for no apparent reason – page 746
o So white patches from candida or lichen planus are not leukoplakia
o About 3% of people have leukoplakia, and only at most ¼ is precancerous
§ But until proven otherwise, leukoplakia is considered precancerous
o Leukoplakia can be hyperkeratotic over a thick acanthotic mucosal epithelium, or be dysplastic
- Erythroplakia – red, velvety, possible eroded area in the oral cavity that isn’t raised and may even depress – page 745
o The epithelium is atypical and dysplastic, making it much higher risk for malignant transformation than leukoplakia
- Both leukoplakia and erythroplakia can happen at any age, but are most common at ages 40-70, and more often in males
- The most common cause of leukoplakia & erythroplakia is tobacco, both smoke & chew
- Most (95%) of cancers of the head and neck are squamous cell carcinomas (HNSCC), usually coming from the oral cavity
o HNSCC is an aggressive epithelial malignancy that is one of the most common cancers in the world
o Long term survival from a HNSCC is less than 50%
§ Early stages have good survival rates, but late stage is pretty bad
§ This is due to the cancer being diagnosed usually when it’s already reached late stage
o HNSCC’s also have the highest rate of developing more than one primary tumor of any cancer, which also decreases chances of survival
o Field cancerization – theory saying multiple individual primary tumors develop independently in the upper aerodigestive tract from years of chronic exposure of the mucosa to carcinogens
o People with an HNSCC that survives 5 years has a 1/3 chance of developing a second primary tumor in that time period
o People with one tumor have decent survival rates, and the most common cause of death from one primary tumor is development of a second primary tumor
o In north America and Europe, HNSCC is most common in middle-aged men who have been chronic abusers of smoked tobacco and alcohol
§ Both alcohol and smoking increase the risk on their own, let alone together
o At least half of oropharyngeal cancers, especially those involving the tonsil, base of the tongue, and oropharynx, have oncogenic variants of HPV
o HPV-associated tumors have a better outcome than those without HPV
o A family history of a head and neck cancer is a risk factor
o Actinic radiation (sunlight) and pipe smoking predisopose to cancer of the lower lip
o In Asia and India, chewing betel quid and paan predisposes to oral cancer
o Chronic irritation could act as a “promoter” of cancer
o The first change from normal to HNSCC cancer is loss of heterozygosity (LOH) and promoter hypermethylation that leads to inactivation of p16 – page 747 top pic
§ P16 is cyclin-dependent kinase inhibitor (CDKI)
§ This change takes you from normal to hyperplasia/hyperkeratosis
o Next is mutation to p53 tumor suppressor gene, which causes dysplasia (CIS)
o Then there is amplification and overexpression of cyclin D1 gene, which activates cell cycle progression, which now makes it malignant
o Epidermal growth factor (EFGR) is overexpressed in a lot of HNSCC
o Squamous cell carcinomas can arise anywhere in the oral cavity, but its favorites are the ventral surface of the tongue, floor of the mouth, lower lip, soft palate, and gingiva – p. 747
o In early stages, cancers of the oral cavity appear as either raised, firm, pearly plaques, or as irregular rough or warty areas of thickening, and both appearances can be superimposed on leukoplakia or erythroplakia
o Oral cancers don’t need to progress to full-blown dysplasia (carcinoma in situ) before they are able to invade, unlike cervical cancers (HPV)
o Usually oral cancer spreads to local cervical lymph nodes before it goes anywhere else
o Favorite sites for oral cancer to spread to distantly are the lungs, liver, and bones
- Odontogenic cysts and tumors:
o Epithelial lined cysts of the jaw are common – most come from the odontogenic epithelium in the jaws
o Dentigerous cysts – developmental cyst that originates in the crown of an unerupted tooth from degeneration of the dental follicle
§ Shows single lesions w/ an impacted 3rdmolar (wisdom tooth) on radiograph
§ Treat by removing it completely, because if not all of it is removed, it recurs or can become cancerous
o Odontogenic keratocyst (OKC) – developmental cyst that’s locally aggressive and recurs a lot
§ OKCs are most common from age 10-40, more often in guys, and in the posterior mandible
§ They show up on radiograph as radiolucencies
§ The cyst is lined with keratinized stratified squamous epthelium
§ Again completely remove it, or it commonly recurs
§ Multiple OKCs can be a sign that it’s nevoid basal cell carcinoma syndrome (Gorlin syndrome) from mutations to the tumor suppressor gene PTCH
o Periapical cyst – inflammatory cyst that are extremely common at the apex of the teeth
§ Periapical cysts develop from chronic inflammation of the tooth pulp, which can be caused by caries or tooth trauma that leads to inflammation
§ The inflammation can cause necrosis of the pulp tissue, which can move through the length of the root, and exit the apex of the tooth into the surrounding alveolar bone, causing a periapical abscess
§ The inflammation persists from continued presence of bacteria or other inflammatory causes, so you treat by removing that offense
o Odontogenic tumors – tumors from the odontogenic epithelium or ectomesenchyme
§ Odontoma – most common type of odontogenic tumor, that comes from the epithelium and causes depositions of enamel and dentin
The most common problems of the nose are inflammatory diseases, usually as the common cold from a virus, which can often be complicated by a superimposed bacterial infection (which is more serious)
- Infectious rhinitis (aka common cold):