The Malignant Skin Tumors; I.e. bad-tempered tumors, are mainly classified into four types of tumors, which are as follows, in order from the least malignant to the most malignant: keratoacanthoma, basal cell epithelioma, squamous cell carcinoma or spinalioma, and malignant melanoma.

Keratoacanthoma is a callus-like formation that has a central crater filled with keratin plug. It grows within weeks up to a specific size. The total excision and pathological examination of entity provide the sufficient treatment. Chemotherapy or radiotherapy as an add-on therapy is not necessary.

Basal cell epithelioma is in the form of a nodule with an ulcerated center. Pearl drop-like papules are observed on the borders of the ulcerated part. These borders are also called as the rolled borders. In some cases, it may be black as malignant melanoma. This type of basal cell epithelioma is called as pigmented basal cell epithelioma. In some cases, it is seen in the form of an expanding plaque. This type of basal cell epithelioma is called as superficial basal cell epithelioma. This tumor reaches a specific size within months. It does not metastasise, and is not life-threatening. However, it develops rapidly in regions such as nose and ears, and gnaws and destroys such tissues. Therefore, the early diagnosis, total excision and pathological examination thereof are required. In elderly patients that cannot be subjected to a surgery, cryotherapy can be performed. As add-on therapies, chemotherapy and radiotherapy are generally not required.

Squamous cell carcinoma may develop beneath the precursor lesions such as chronic wounds, radiodermatitis, lupus vulgaris and seborrheic keratosis, or on the normal skin zones, as a result of a long term exposure to sunlight. Rarely, it may metastasise. In addition to the total excision and pathological examination of the respective entity, radiotherapy and chemotherapy may be needed.

Malignant melanoma is a blackberry-like tumor that mostly develops on the nevuses, but may also appear suddenly on the normal skin zones. Sunlight and viral infections are among the primary causes thereof. If the respective nevus is in tendency to be malignant, it should be removed with a wide margin. In some cases, the excision margin is so wide that a graft or flap may be needed. In some cases, regional lymph nodes are also excised after 15 days. Chemotherapy is performed. Metastasis should be scanned by gallium citrate 67 tomography and PET scan, since this very malignant tumor is able to metastasise to all remote organs. Generally, it is a fatal tumor unless the respective nevuses are removed in an early phase. Therefore, we should have controlled our nevuses before and after every summer, and protect ourselves from sunlight as recommended by the physician.