Treatment of choice in intracran al ALL is:
**Intracranial Acute Lymphoblastic Leukemia (ALL) Treatment**
**Core Concept**
Intracranial ALL is a medical emergency requiring prompt treatment to prevent central nervous system (CNS) relapse. The treatment choice is guided by the need to achieve CNS remission and prevent further complications.
**Why the Correct Answer is Right**
The treatment of choice for intracranial ALL is intrathecal chemotherapy with methotrexate (IT-MTX). Methotrexate is a chemotherapeutic agent that crosses the blood-brain barrier, allowing it to reach the CNS and effectively treat leukemic cells. IT-MTX is administered directly into the cerebrospinal fluid (CSF) via lumbar puncture, providing high concentrations of the drug in the CNS.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because systemic chemotherapy alone is not sufficient to achieve CNS remission in intracranial ALL.
**Option B:** This option is incorrect because cranial radiation therapy is not the primary treatment for intracranial ALL, although it may be used as a salvage therapy.
**Option C:** This option is incorrect because prophylactic cranial irradiation is not the standard treatment for intracranial ALL, and its use is generally reserved for specific cases.
**Clinical Pearl / High-Yield Fact**
Intrathecal chemotherapy is a crucial component of CNS-directed therapy in ALL, and IT-MTX is the preferred agent due to its ability to cross the blood-brain barrier and achieve high concentrations in the CNS.
**Correct Answer: B. Intrathecal methotrexate.**