How to differentiate skin cancer from skin carcinoma in situ

Skin cancer can be divided into squamous cell carcinoma and basal cell carcinoma, both of which are mostly caused by sun exposure; skin carcinoma in situ is also mostly caused by sun exposure. The symptoms, causes and distribution locations of the two are very similar, and many patients often confuse the two conditions. In medical clinical practice, it is advisable to distinguish them based on the patient's age of onset, location of the disease and color of the disease.

Main features of skin cancer:

Common early skin cancers include squamous cell carcinoma and basal cell carcinoma. Squamous cell carcinoma is highly malignant and often occurs in the skin, mucous membranes and the junction of skin and mucous membranes in the head, neck, limbs, trunk and other parts. Ulcers can form in the early stage and grow in an invasive manner. When it infiltrates deep tissues, it is often accompanied by purulent infection and lymph node metastasis. It is easy to evolve on the basis of xeroderma pigmentosum and senile keratosis. Basal cell carcinoma is more common in the elderly, and is prone to occur in the forehead, eye sockets, eyelids, nose, and around the ears. It is less malignant and grows very slowly. It is very common for the course of the disease to exceed 10 to 20 years. At the beginning, it is mostly a small thickened mass, which gradually bulges and infiltrates to the surrounding area, and rarely metastasizes.

The main features of skin carcinoma in situ are:

Skin carcinoma in situ is common in people aged 60 or 70, with a male-female ratio of 0.8 to 1.2:1. The most common site is the head and neck, accounting for 44% to 54%. It can also occur in the hands, trunk, buttocks, anus and genital mucosa, oral mucosa and nail bed. About 72% of cases occur in sun-exposed areas, mostly single, but there may be 2 to 3 lesions, manifested as light red or dark red slightly raised skin lesions, with many desquamations and scabs on the surface. The lesions gradually expand to become round or annular papules with clear edges, covered with brown or gray thick scabs, which are not easy to fall off. If forcibly peeled off, fine granular or fine papillary moist surfaces are revealed, with slight tingling locally. The course of the disease develops slowly and can last for 5 to 35 years. Ulcers rarely occur. 20% to 30% can develop into invasive cancer, and about 20% have regional lymph node metastasis. The prognosis of skin carcinoma in situ combined with cancers of other organs is poor.