Epidermoid carcinoma.
3.3.4 Squamous Cell Carcinoma
Synonyms
Epidemiology
Incidence 30-50 /100,000 per year.
Definition
Malignant keratinocytic tumour with tendency to progessively invade and metastasize.
Aetiology & Pathogenesis
Arises on previously damaged skin: UV, ionizing radiation, arsenic, tar, soot, abnormal scars, HPV. Precursors: actinic keratoses, in situ carcinoma, scars, chronic ulcers. Predisposing factors: skin types I and II, occupations with marked UV exposure (farmers, mountaineers, sailors, roofers and construction workers), transplanted patients and those with chronic immunosuppression.
Signs & Symptoms
Usually in sun-exposed areas, irregular, often hyperkeratotic papules or nodules, easily ulcerate.
Localisation
May appear all over the skin, in particular sun-exposed sites (head, ear, neck, lower lip, back of hands, forearms, shins).
Classification
According to keratinocyte differentiation (Broder’s grade 1 to 3) by histology.
Laboratory & other workups
Not necessary.
Dermatopathology
Hyperkeratosis, strands of epithelium extending into dermis, atypia, mitoses, inflammatory infiltrate, dyskeratosis, single cell necrosis (apoptosis with eosinophilic cytoplasm), keratin pearls. Degree of differentiation: grade1 (well-differentiated, risk of metastasis 1-2%), grade 3 (poorly differentiated with high risk).
Course
Patients with immunosuppression and transplantation have higher risk of metastasis.
Complications
Depending on the localisation: local invasion of deeper structures and metastasis.
Diagnosis
Clinical features and histology. Continuously growing, hyperkeratotic, sometimes ulcerated nodular usually non-pigmented lesions.
Differential diagnosis
Prevention & Therapy
Depends on size and localisation. Excision should be done with histologically proven margins, radiotherapy, radiofrequency therapy with bleomycin, immune modulators (check point inhibitors).
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