Leukemia

KEY FACTS

TERMINOLOGY

• Extramedullary leukemic tumors

• Synonyms: Granulocytic sarcoma, chloroma

IMAGING

• Best diagnostic clue: Homogeneous enhancing tumor(s) in

patients with known or suspected myeloproliferative

disorder

• Meningeal (dural-based or pial) > intraparenchymal lesions

• NECT: Hyperdense

• CECT: Moderate uniform enhancement

• MR

○ T2/FLAIR iso- to hypointense

○ Restricted diffusion on DWI

TOP DIFFERENTIAL DIAGNOSES

• Metastatic neuroblastoma

• Meningioma

• Extraaxial hematoma

• Extramedullary hematopoiesis

• Langerhans cell histiocytosis

PATHOLOGY

• CNS leukemia presents in 3 forms

○ Meningeal disease (usually with acute lymphoblastic

leukemia)

○ Intravascular aggregates (leukostasis): Can rupture,

hemorrhage with markedly ↑ leukocyte counts

○ Tumor masses (chloroma)

• Multiple other intracranial manifestations, complications of

leukemia/treatment

○ Posterior reversible encephalopathy syndrome (PRES)

○ Posttransplant lymphoproliferative disease after bone

marrow transplantation

○ Invasive fungal infection

○ Venous thrombosis associated with chemotherapy

○ Late development of cavernous angiomas after radiation

therapy

(Left) Coronal graphic shows

multiple foci of leukemic

infiltrates in the skull

base/paranasal sinuses ſt,

hypothalamus/infundibulum

﬊, basal ganglia ﬉, and dura

﬇. Green color observed at

pathology results in the name

"chloroma." The accepted

term is "granulocytic

sarcoma." (Right) Axial NECT

scan in a child with acute

myelogenous leukemia (AML)

and a palpable scalp mass

shows a hyperdense intra- ﬇

and extracranial mass ſt that

centers on the calvaria.

(Left) Axial T2WI in a child

with AML demonstrates a

hypointense parietal mass ſt

surrounded by a collar of

edema st. AML with

parenchymal metastasis

(cerebral granulocytic

sarcoma) is rare. (Right) NECT

scan in a 5-year-old girl with

AML shows chloroma

infiltrating both trigeminal

nerves, enlarging the cisternal

﬈ and Meckel cave segments

﬊. (Courtesy N. Aggarwal,

MD.)

Cysts, and Disorders

Brain: Pathology-Based Diagnoses: Neoplasms,

149