Which of the following features most reliably distinguishes malignant tumors from benign tumors?

A 70-year-old man presents with a non-healing, scaly, ulcerated lesion on his lower lip. He has a long history of sun exposure. Biopsy reveals invasive nests of atypical squamous cells with keratin pearls.

What is the most likely diagnosis?

Which of the following best explains why basal cell carcinoma rarely metastasizes?

A 62-year-old male presents with a non-healing ulcer on the floor of his mouth for the past 3 months. The lesion is indurated with raised, irregular borders. He also reports pain while eating. On examination, there is a tender, enlarged cervical lymph node palpable on the left side, measuring approximately 2 cm. The patient has a significant history of tobacco and alcohol use. A biopsy of the lesion reveals keratin pearls, pleomorphism, and abnormal mitotic figures. The tumor cells show marked dysplasia and invasion into the underlying connective tissue.

What is the most possible diagnosis?

Which of the following cancers is the most likely diagnosis and also the leading cause of cancer-related death in both men and women worldwide?

A 65-year-old man presents with a pearly, translucent nodule with telangiectasias on the right side of his nose. He states it has been slowly growing over several months. There is no bleeding or ulceration. He has significant cumulative sun exposure from years of working outdoors.

What is the most likely diagnosis?

Which of the following best describes the “E” in the ABCDE criteria used to evaluate pigmented skin lesions for melanoma?