Final answer:
Management of a 0.5cm lesion in the anus with no local extension and negative lymph nodes typically starts with a biopsy. If benign, it may need only observation; if malignant, it could require excision or local destruction, with follow-up.
Step-by-step explanation:
The management of a 0.5cm diameter lesion in the anus that shows no local extension and has negative lymph nodes typically involves a conservative approach. The first step should generally consist of a pathological assessment through a biopsy to verify the nature of the lesion. If the lesion is found to be benign, it may only require observation or local excision. If the lesion is malignant, treatment options may include surgical excision or local destruction (e.g., electrocautery, laser therapy), possibly followed by close follow-up due to the small size and lack of extension. It's essential to consult with a colorectal specialist or an oncologist to determine the appropriate management plan based on the complete clinical context.