Parasyndesmophytes

Parasyndesmophytes or non-marginal bulky syndesmophytes or floating syndesmophytes are, paravertebral dystrophic soft tissue calcifications or heterotopic ossifications.

Etiology

They are known to be seen in ⁴: 

• psoriatic arthritis

• reactive arthritis

Radiographic features

Initially parasyndesmophytes begin at a distance from the vertebral body and intervertebral space.

In early disease, these appear as asymmetric syndesmophytes, which appear linear or curvilinear, thick and fluffy and parallel to the lateral surface of vertebral bodies.

Ultimately they increase in size to form large and bulky masses, merging with the underlying bone and disc.

Differential diagnosis

Late stages can render differentiation from the related counterparts syndesmophytes and flowing ossifications somewhat difficult.