Age / Sex : 38 / F

Chief complaint : Palpable lesion in the lower back with pain

What is your impression?

Two weeks later, you can see the final diagonosis with a brief discussion of this case (Please submit only one answer).

Courtesy : Eugene Lee, Seoul National University Bundang Hospital

Discussion

Answer: hydroxyapatite crystal deposition disease (with acute inflammation) at supraspinous ligament of L2-3 level

Findings:

• Initial plain radiograph : focal calcification at posterior aspect of spinous process (L2) inferior margin

• MRI : T1 and T2 low signal intensity foci at supraspinous ligament of L2-3 level with adjacent soft tissue inflammatory enhancement

• Follow-up plain radiograph : nearly resolved previous calcification at supraspinous ligament of L2-3 level on 2 months follow-up

Differential Diagnosis: none

Discussion:

 HADD (Hydroxyapatite crystal deposition disease)

• HADD in the spine is found in three typical locations : (1) within the longus colli muscle, (2) surrounding the dens, and (3) within the intervertebral discs, the anterosuperior portion of the longus colli muscle is most commonly involved


• The ligaments and apophyseal joints may also be calcified.


• Paraspinal HADD masses can narrow the spinal canal, causing a symptomatic radiculopathy or neuropathy.


• Paraspinal HADD may also be symptomatic due to the inflammatory response elicited by crystals.


• MRI : HADD in tendons/ligaments has low signal on T1 and T2WIs. Sometimes there is surrounding edema, which appears on MRI as a rim of increased signal intensity on T2WIs. Combined active inflammation can be enhanced.

References:

• Imaging of arthritis and Metabolic Bone disease, Elsevier Health Sciences, 2009