Oral Pathology in Clinical Dental Practice. Robert E. Marx
Hairy Leukoplakia
• Dental Lamina Rests/Epithelial Inclusions (Bohn’s Nodules and Epstein Pearls)
• Acute and Chronic Radiation Mucositis
• Oral Squamous Cell Carcinoma
Benign Hyperkeratosis
Nature of disease
A thickening of the mucosal epithelium with the production of orthokeratin without epithelial dysplasia.
Predilections
Occurs mostly in adults related to either mechanical irritation or a chemical reaction or unrelated to any observable cause. There is no sex or racial predilection. It may also be idiopathic.
Clinical features
A white patch referred to as leukoplakia. It is usually asymptomatic. It is often slightly elevated and may be thickened but will not be indurated.
Radiographic presentation
None.
Differential diagnosis
As a patch of clinical leukoplakia, it must be distinguished from premalignant dysplasia, carcinoma in situ, verrucous carcinoma, and invasive carcinoma. Additionally, lichen planus and Candida infection may be considered.
Microscopic features
A thicker-than-normal keratinocyte layer with a surface of lightly eosinophilic, wavy orthokeratin. The keratinocytes will appear to be normal without mitotic figures or nuclear pleomorphism.
Suggested course of action
Remove any obvious mechanical irritation (eg, denture irritations, toothbrush trauma, patient habits, etc) and/or chemical reaction (eg, irritating mouthwashes, certain spices or flavoring agents, etc). If there is no response or resolution within 2 weeks or if no obvious cause is noted, a biopsy is indicated.
Treatment
It is a relief to patients to hear that their benign hyperkeratosis lesion is not considered to be a cancer. However, incisional and even excisional biopsy cannot predict either regrowth or a sampling error that may result in a squamous cell carcinoma developing later. Therefore, a 6-month recall schedule is recommended even though no specific treatment is required.
Leukoplakia
Nature of disease
A white patch on the oral mucosa. Three conditions can present as a clinically apparent white patch: acanthosis/hyperkeratosis, Candida, or fibrin.
Predilections
Can occur at any age but is more often seen in adults. There is no sex or racial predilection.
Clinical features
A white patch of oral mucosa most commonly noted on the buccal mucosa, lateral border of the tongue, or floor of the mouth.
Radiographic presentation
None.
Differential diagnosis
Clinical leukoplakia may only represent an ulcer with a fibrin base or Candida and sometimes lichen planus by virtue of its acanthosis and hyperkeratosis. However, after benign hyperkeratosis, the most serious considerations are premalignant dyplasias, carcinoma in situ, verrucous carcinoma, and invasive squamous cell carcinoma.
Microscopic features
The three entities that cause a clinical leukoplakia will appear different:
1. Fibrin: Thin strands of light eosinophilic staining over a wound base with inflammation.
2. Candida: Vertically positioned hyphae with prominent periodic acid-Schiff (PAS) or silver staining on an epithelial surface.
3. Acanthosis/hyperkeratosis:
a. Acanthosis/benign hyperkeratosis: A thickened keratinocyte layer without cellular atypia but with surface keratin.
b. Premalignant dysplasia: Various degrees of epithelial atypia above an intact basement membrane.
c. Carcinoma in situ: Severe epithelial dysplasia with nuclear pleomorphism and abnormal mitotic figures from the basal cell layer to the surface.
d. Verrucous carcinoma: A significant exophytic proliferation as well as a blunted endophytic proliferation of epithelial cells but with an intact basement membrane beneath which most often resides a dense inflammatory response.
e. Invasive carcinoma: Atypical epithelial cells forming bundles and cords through the basement membrane into the underlying tissues.
Suggested course of action
Biopsy and/or refer to an oral and maxillofacial surgeon.
Treatment
Treatment will vary according to the biopsy result. For:
♦ Fibrin: Wound care and treatment of the underlying etiology, as well as observation and surveillance for acanthosis/hyperkeratosis.
♦ Premalignant dysplasia: Excision with frozen section control.
♦ Carcinoma in situ: Excision with frozen section control.
♦ Verrucous carcinoma: Excision with frozen section control.
♦ Invasive carcinoma: Excision with frozen section control and evaluation for radiotherapy and/or chemotherapy.