Masses on the Back

Lumbosacral masses can be caused by a number of specific anomalies, especially meningomyelocele, which is the most common cause. The differential diagnosis for lumbosacral mass can be summarized as follows:

Fig 1, Fig 2, Fig 3

Major differential diagnoses

Meningomyelocele (most common)

• spinal dysraphism
• solid-cystic mass located at the lumbosacral spine in most cases
• associated cranial signs of spina bifida, such as lemon sign, banana sign, and ventriculomegaly

Sacrococcygeal teratoma (SCT) (uncommon)

• solid-cystic, solid predominantly in most cases but entirely cystic in 15% of cases
• high vascularization
• intra-abdominal components in most cases with a displacement effect on internal structures
•  usually located in the sacrococcygeal area

Limb-body wall complex (uncommon)

• solid-cystic asymmetric mass
• abnormal spinal curvature
• no specific location
• severe abdominal wall defects
•  limb defects
• no or very short umbilical cord

Amniotic band syndrome (uncommon)

• solid-cystic asymmetric mass
• no specific location
• associated limb reduction/constriction defects
• amniotic band in the amniotic cavity.

Minor differential diagnoses

• Artifacts: extrafetal mass, such as chorioangioma attached to the fetal back
• Rare tumors: lipomas, lipomyelomeningocele, and large hemangioma.

Fig 1:  Sacrococcygeal teratoma   Sagittal scan of the spine: abnormal complex solid mass (*) beneath the sacral spine

Fig 2:  Large meningomyelocele   Scan of lower spine: large solid mass with heterogeneous echodensity (solid circle) (arrow = sacrum)

Fig 3:  Lumbar meningocele   Sagittal scan of the spine: small solid mass protruding from lumbar region