Diagnosis and differentiation of squamous cell carcinoma of the skin

The diagnosis of squamous cell carcinoma of the skin is not difficult. A clear diagnosis can usually be made based on typical clinical manifestations combined with histopathological examination. Immunoperoxidase staining with anti-prokeratin and anti-keratin monoclonal antibodies or observation of tension filaments under an electron microscope can also assist in the diagnosis.

This disease should be differentiated from keratoacanthoma, basal cell epithelioma and other malignant skin tumors. Differential diagnosis often relies on early biopsy and histopathological examination. Grade I squamous cell carcinoma of the skin needs to be differentiated from pseudocarcinomatous hyperplasia and keratoacanthoma; the diagnosis of grade II and grade III squamous cell carcinoma is relatively easy; grade IV squamous cell carcinoma should be differentiated from spindle cell sarcoma and amelanotic malignant melanoma.

The lesions of keratoacanthoma are hard, dome-shaped nodules with a central crust in the shape of an umbilicus. They grow fast, and some lesions may disappear naturally after a few months. Histopathological features are acanthosis, a central keratinized mass opening on the surface, like a crater, and a lip-like protrusion of the epidermis around the crater. There are large squamous cells with pale eosinophilic cytoplasm extending into the dermis but not falling into the dermis.