📖 Definition: Anaplastic [Neurosurgery Wiki]

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===== 📖 Definition: Anaplastic =====

**Anaplastic** (from Greek *ana-* = backward + *plasis* = formation) refers to cells or tissues that have **lost their normal structure and differentiation**, indicating **malignant transformation**.

==== 🔬 Pathological Characteristics ====
Anaplastic cells typically show:
  * **High mitotic activity**
  * **Nuclear atypia** (abnormal nuclear shape and size)
  * **Increased cellularity**
  * **Loss of normal tissue architecture**
  * Often **poorly differentiated** or **undifferentiated**

==== 🧠 In Neuro-oncology ====
In the context of brain tumors:
  * **Anaplastic gliomas** are classified as **WHO Grade 3**
  * They are **malignant and infiltrative**, but **do not** show necrosis or microvascular proliferation (hallmarks of Grade 4)
  * Common anaplastic gliomas:
    * **Anaplastic astrocytoma**
    * **Anaplastic oligodendroglioma**

==== 📌 Summary ====
“Anaplastic” denotes **malignancy with loss of differentiation**, often used in the classification of **Grade 3 tumors** to indicate a more aggressive behavior than low-grade (Grade 1–2) tumors.