Non-clinical sciences/Pathology · Neoplasia

Benign vs malignant neoplasia

What it means

Benign: well-circumscribed/encapsulated, slow, low mitotic rate, well-differentiated, no invasion or metastasis. Malignant: infiltrative, ill-defined, rapid, high (often atypical) mitoses, poorly differentiated/anaplastic, local invasion, metastasis, necrosis and neo-angiogenesis.

Worked example

Capsular breach, vascular invasion and metastasis are the hallmarks that define malignancy.

In the exam

A lesion is poorly differentiated with frequent abnormal mitoses, invades surrounding tissue and has spread to regional nodes.

What settles it

Metastasis and invasion define malignancy; benign tumours may be large but stay localised and differentiated.

Classically confused with

Metaplasia, dysplasia, anaplasia

Source: StatPearls — Neoplasia