Pathology of Squamous Cell Carcinoma

Squamous Cell Carcinoma of the Lips

• Found in light-skinned individuals with chronic exposure to UV radiation from sunlight
• 70% of affected individuals have outdoor occupations
• Usually associated with actinic cheilosis
• May arise at the site where the patient holds a cigarette, cigar, or pipe
• Almost 90% of lesions are located on the lower lip

Clinical Features

• Crusted, oozing, nontender, indurated ulceration, usually less than 1 cm
• Usually grows slowly
• Most patients are aware of a “problem” in the area for 12 to 16 months before diagnosis
• Perineural invasion may result in extension of the tumor into the mandible through the mental foramen

Histopathologic Features

• Dysplastic proliferation involving the entire thickness of the epithelial (carcinoma in situ)
• Invasion from the basal layer to the surface or top-to-bottom by islands of tumoral cells
• Invasion by irregular extension of squamous tumoral cells through the basement membrane and into subepithelial connective tissue
• At the earliest moment of invasion, the adjectives superficially invasive or microinvasive are often used
• Squamous cells or islands of cells proliferate within the connective tissue without attachment to the surface epithelium
• The invading tumor destroys normal tissue and may extend deeply into underlying adipose tissue, muscle, or bone, which will be replaced by squamous tumoral cells
• Lesional cells may breach the perineurium that encases nerve bundles (perineural invasion) or may invade the lumina of veins or lymphatics (vascular invasion)
• The tumor may induce dense fibrosis (desmoplasia or scirrhous change) and the formation of new blood vessels (angiogenesis)

Treatment

• Surgical excision
• Radiotherapy
• Chemotherapy
• Immunotherapy

Melanoma

• Rarely affects oral mucosa (0.1 to 8% of malignant melanoma)
• Clinical features: brown patch or blue-black, mostly polychrome, with regular limits, slightly elevated, painless, and frequently observed around sixty on the palate and gingiva
• Diagnosis is often late, with symptoms such as ulcerated and bleeding tumor nodule, loss of teeth due to underlying bone destruction, and cervico-facial lymph nodes metastasis
• Perineural invasion may cause paresthesia

Squamous Cell Carcinoma Sites

• Most common sites: tongue (usually the posterior lateral and ventral surfaces), floor of mouth, and gingiva
• Other sites of involvement (in descending order of frequency): buccal mucosa, labial mucosa, hard palate, and lips