Squamous Cell Carcinoma

ICD-11

2C31

Synonyms

Epidermoid carcinoma.

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

Keratoacanthoma, actinic keratoses, Bowen’s disease, basal cell carcinoma, verrucae vulgaris, hypertrophic lichen planus.

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).

3.3.4 Squamous Cell Carcinoma