Pediatric Leukemia

Etiology: Hematological neoplasm caused by overproduction of immature (blasts) or abnormally differentiated cells of hematopoietic system in bone marrow that often extends into peripheral blood
Imaging Chest:
— Mediastinal mass
Imaging Gastrointestinal:
— Hepatosplenomegaly due to diffuse infiltration of liver and spleen by leukemic cells
Imaging Genitourinary:
— Bilateral nephromegaly due to diffuse infiltration of kidneys by leukemic cells
Imaging Musculoskeletal Radiograph:
— 25% of bone lesions visible via radiograph
— Leukemic lines are thin metaphyseal lucent bands often about knees
— Osteoporosis
— Metaphyseal lucencies with or without fractures
— Permeative lesions
— Aggressive cortical loss
— Aggressive periosteal reaction
Imaging Musculoskeletal MRI:
— Extensive marrow replacement
— Relapsed leukemia can appear as multiple well-circumscribed, enhancing spots in bone marrow
Imaging Spine Radiograph:
— Diffuse osteopenia with loss of vertebral body height (vertebra plana)
Imaging Spine MRI:
— Diffuse T1 hypointense and T2 hyperintense signal with contrast enhancement (vertebral body marrow should be brighter than the disc on T1) with adjacent soft tissue and leptomeningeal disease
Imaging Neurological:
— Subcortical calcification can occur after methotrexate treatment
DDX: Metastatic neuroblastoma, Langerhans cell histiocytosis, osteomyelitis, Ewing sarcoma, lymphoma
Complications: L-asparaginase used to treat acute lymphoblastic leukemia is cause of acute pancreatitis
Treatment:
Clinical:
— Most common pediatric malignancy
— Presentation: Markedly elevated and abnormal white blood cell count along with splenomegaly

Radiology Cases of Leukemia

Radiology Cases of Mediastinal Involvement in Acute Lymphoblastic Leukemia

CXR of acute lymphocytic leukemia with infiltration of the thymus — CXR AP+lateral shows a large anterior mediastinal mass centered in the region of the thymus.

CXR and CT of acute lymphocytic leukemia / ALL — CXR AP and lateral (above) shows left hilar and superior mediastinal lymphadenopathy which is better demonstrated on the axial CT with contrast of the chest (below).

Radiology Cases of Splenic Involvement in Acute Lymphoblastic Leukemia

AXR of acute lymphocytic leukemia — AXR shows diffuse enlargement of the liver and spleen.

Radiology Cases of Chloroma in Acute Myeloid Leukemia

Radiograph and CT of chloroma in acute myelocytic leukemia — Lateral radiograph of the airway (above) shows a large amount of retropharyngeal soft tissue swelling. Axial CT with contrast of the neck (below) shows a large round low density lesion in the left parapharyngeal space.

Radiology Cases of Bone Involvement in Leukemia

Radiograph of leukemia of the spine — Lateral radiograph of the thoracic spine shows diffuse osteopenia in the vertebral bodies with loss of height (vertebra plana) in all of the vertebral bodies.

Radiology Cases of Bone Involvement in Acute Lymphoblastic Leukemia

Radiograph of acute lymphoblastic leukemia in the spine — Lateral radiographs at presentation of the thoracic (left) and lumbar (middle) spine show diffuse osteopenia and loss of vertebral body height throughout the spine while lateral radiograph obtained a decade later of the lumbar spine (right) shows a faint bone within bone appearance of the vertebral bodies.

Radiology Cases of Typhlitis in Acute Lymphoblastic Leukemia

US of typhlitis — Transverse (above) and sagittal (below) US of the cecum show marked thickening of the wall of the cecum which is lying above the right psoas muscle.

CT of typhlitis — Axial CT with IV and oral contrast of the abdomen shows marked thickening of the wall of the cecum. The remainder of the colon was unremarkable.