Malignant lesions and pre-cancerous conditions in Oral Cavity

Malignant lesions and pre-cancerous conditions in Oral Cavity

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July 21, 2017 | Last update on July 28, 2017

The main types of malignant tumours of the mouth are the following :

  • Carcinomas
  • Melanomas
  • Lymphomas
  • Sarcomas
  • Metastatic tumours
  • Malignant Odontogenic tumours

Carcinoma is the most common (75%) type of malignant tumour of the Oral Cavity
that derives from the epithelium of the Oral mucosa, the epithelium of the salivary
ducts or from intraosseous epithelial elements .
The location as well as the lack of pain at initial stages is the main cause of rather late
diagnosis. As a result to the above >50% of the patients seek medical advice at late
stages.


Therefore, the Dentist’s role is crucial in identifying any ambiguous lesion of the Oral
mucosa and referring the patient to a Specialist for consultation and treatment.
Oral cancer appears as an erosion or ulceration without healing tendency or as a
whitish patch or as a nodule that grows progressively and finally becomes ulcerated.
The majority of Oral cancer cases have their origin in a horse-shoe area defined by the
lateral tongue, floor of the mouth and the lingual aspect of the lower gingivae..

 

Cancer oral cavity and lower lip

The most common site of oral cancer is the middle third of the lateral aspect-
margin of the tongue. During recent decades an increase of tongue cancer incidence
(>30%) has been shown

Oral cancer in general is considered as a malignancy for the elderly and the
male/female ratio is 2-3:1. However, for tongue cancer the male to female ratio is 1.5/1.Moreover, the last decade there is significant increase of oral cancer in younger ages mostly related to HPV16 (sexually transmitted virus). Despite the advancements in Oral cancer research, bio-technology and in diagnostic and therapeutic approach, the mortality rate is still high. Tumours diagnosed when >4cm the risk of concomitant neck disease (positive lymph nodes) is >80%


The primary intraosseous carcinoma of the jaw


Derives from intraosseous epithelial remnants in the lower jaw mostly in the posterior region and
usually close to an impacted wisdom tooth. Causes osteolysis and destruction of the bony tissue and
only at late stages appears as a malignant ulceration of the covering mucosa. Any symptoms or signs are
easily misdiagnosed as related to the impacted wisdom tooth and the diagnosis is usually delayed

Predisposing factors for Oral/Oro-Pharyngeal Ca:

  • Smoking and smokeless tobacco
  • Systematic alcohol consumption or combination of the above
  • Virus infection mainly Human Papilloma Viruses (HPV-16), EBV,
  • HSV,CMV.
  • Diet low in Carotene and Vit C
  •  Vit E, B12,A and Fe deficiency/Patterson-Kelly Syndrome
  •  Poor Oral hygiene and ill-fitted- irritating prostheses or filings etc
  •  Family Syndromes (congenital dyskeratosis, Fanconi anemia)
  •  Systematic exposure to the sunlight (lip Ca)
  •  Chronic immunosuppression
  •  Genetic factors though not consistent are important (mutation or loss of allele in tumour suppressor genes eg P53 on chromosome 17 and MTSG on chromosome 9) or mutation in proto-oncogenes to oncogenes eg c-ras in Indian smokers

 

Precancerous conditions


Pathologic changes in the Oral mucosa intertwined with higher risk for
malignant change comparing to the normal mucosa,

Leucoplakia (whitish lesion-patch that cannot be characterized as any
other definable lesion)

  •  Erythroplakia (reddish velvety smooth patch well defined from the
  • surrounding mucosa)
  • Erythroleucoplakia
  • Sublingual fibrosis (relatively common in Asians)
  • Lichen planus with dysplasia
  • Actinic or Solar cheilitis (chronic exposure to sunlight that leads to drying, crusting, fissuring vermilion border)

Melanoma of Oral Cavity

Uncommon (1% of total melanomas) but aggressive malignancy with worse prognosis
than the skin melanoma. However, in Japan consists 4% of total melanomas. Almost
40%-50% of oral melanomas are located in the hard palate There is prevalence in the
age group between 40y-60y. The oral melanomas appear as dark bluish-black lesions.
However, 15% appear as (amelanotic) reddish lesions. Differential diagnosis: other
pigmented lesions, amalgam tattoo and naevi. Treatment of choice is surgical excision
in clear margins plus radiotherapy, chemotherapy and adjuvant therapy.
Prognosis is poor
The 5- year survival rate >5%

 

Lymphoma (Hodgkin, non-Hodgkin) of the oral cavity


Uncommon as primary tumour. Lymphomas of the oral cavity appear as a soft nodule
easily ulcerated due to trauma. Regional lymph nodes are not enlarged at initial
stages.
Lymphoma of naso-pharynx appear as an ulcerated swelling. More common among
immunosuppressed patients as well as in patients diagnosed with RA and Sjogren’s
syndrome.
It is essential for the therapeutic approach of choice, to clarify first whether is a
primary tumour or manifestation of a disseminated disease.
Show good response to radiotherapy. On the contrary the Burkitt lymphoma develops
in children and responds to chemotherapy. 

Sarcoma

Mainly is osteosarcoma of the mandible and represents 7% of body sarcomas. Affects
the body of mandible and develops in younger ages in comparison with the squamous
cell carcinoma. Appears as a firm swelling of the jaw that progressively increase in
size causing pain. Paraesthesia (numbness) in the ipsilateral lower lip is common.
Radical excision along with radiotherapy and chemotherapy is the treatment of
choice.


Melanoma hard palate

Metastatic tumours
Have their origin from: Lung cancer, breast and prostate cancer. Less often are the
metastatic tumours from thyroid and renal carcinomas. The therapeutic approach
depends on the type of primary tumour.

Malignant Odontogenic tumours


Very rare tumours that derive from intraosseous epithelial remnants of the dental
lamina