Lumbar Soft Tissue Mass, Pediatric
Kevin R. Moore, MD
DIFFERENTIAL DIAGNOSIS
Common
Lipomyelomeningocele
Myelomeningocele
Lipoma, Spinal
Spinal Muscle Injury, Traumatic
Scoliosis
Less Common
Plexiform Neurofibroma
Ewing Sarcoma
Lymphoma
Venous Vascular Malformation
Lymphatic Malformation
Abscess, Paraspinal
Rare but Important
Metastases, Lytic Osseous
Hemangiopericytoma
Meningocele, Dorsal Spinal
Pseudomeningocele
ESSENTIAL INFORMATION
Key Differential Diagnosis Issues
Appearance of overlying skin, pertinent clinical information helps limit differential list
Helpful Clues for Common Diagnoses
Lipomyelomeningocele
Lipomyelocele = neural placode-lipoma complex contiguous with subcutaneous fat through dysraphic defect, attaching to and tethering spinal cord
Lipomyelomeningocele = lipomyelocele + meningocele, enlargement of subarachnoid space, displacement of neural placode outside of spinal canal
Myelomeningocele
Posterior spinal defect lacking skin covering ⇒ neural tissue, CSF, and meninges exposed to air
Lumbosacral (44%) > thoracolumbar (32%) > lumbar (22%) > thoracic (2%)
Low-lying cord on post-operative MR imaging does not always = clinical tethering
Lipoma, Spinal
Arise from premature separation (dysjunction) of cutaneous ectoderm from neuroectoderm during neurulation
Profound hypodensity on CT and T1WI hyperintensity characteristic of fat
Use chemical fat saturation or inversion recovery MR techniques to confirm fat content
Spinal Muscle Injury, Traumatic
Paraspinal muscle fiber disruption from indirect forces ⇒ abnormal muscle T2 hyperintensity and swelling
Most commonly from MVA; also athletic injuries, blow from falling objects, direct injury
Scoliosis
General term for any lateral curvature of spine
Dextroscoliosis: Curve convex to right
Levoscoliosis: Curve convex to left
Kyphoscoliosis: Scoliosis with component of kyphosis
Rotoscoliosis: Scoliosis which includes rotation of vertebrae
Short-curve scoliosis usually has underlying abnormalities; consider congenital, neoplasm, or inflammation
Helpful Clues for Less Common Diagnoses
Plexiform Neurofibroma
Long, bulky, multinodular nerve enlargement is pathognomonic for NF1
Often affects sacral or brachial plexi
Ewing Sarcoma
5% of all Ewing tumors in spine (sacrum > rest of spine)
Usually in adolescents or younger adults
Permeative lytic lesion of vertebral body or sacrum involving vertebral body before neural arch
Contiguous spread along peripheral nerves from spine or sacral primary, but may originate in soft tissues
Lymphoma
Lymphoreticular neoplasms with wide variety of specific diseases & cellular differentiation
Multiple types demonstrate variable imaging manifestations
Venous Vascular Malformation
Congenital trans-spatial vascular malformation of venous channels present from birth
May be mass-like, frequently enhances moderately (less than soft tissue hemangioma)
No arterial vessels within lesion, venous channels may be large
Look for phleboliths to make specific diagnosis
Lymphatic Malformation
Congenital trans-spatial vascular malformation of lymphatic channels present from birth
Typically minimal to no enhancement, although septations may enhance, especially if previously inflamed
Fluid-fluid levels strongly suggest diagnosis
May grow rapidly if hemorrhage or concurrent viral infection
Abscess, Paraspinal
Suppuration of paraspinal soft tissue from direct extension or hematogenous dissemination of pathogens
Identification of calcified psoas abscesses suggests tuberculous paraspinal abscess
Helpful Clues for Rare Diagnoses
Metastases, Lytic Osseous
Osteolytic metastases of primary tumor to spine; bone destruction exceeds bone production ⇒ lytic rather than blastic
Lesion usually destroys posterior cortex, pedicle first
Hemangiopericytoma
Vividly enhancing hypervascular neoplasm arising from pericytes expanding/eroding spinal canal with large soft tissue componentStay updated, free articles. Join our Telegram channel
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