Age / Sex : 64 / M

Calcific tendinitis, FCU tendon on pisiform

Discussion

Findings: Echogenic
nodular lesion is seen in FCU tendon inserting pisiform in longitudinal and
short axis views of wrist US. The echogenic nodule shows no acoustic shadowing.
In plain wrist PA and lateral views, small nodular calcifications are seen
superficial to pisiform.

Differential Diagnosis:

1.    
Avulsion
fracture, FCU tendon

2.    
BPOP (Bizarre
parosteal osteochondromatous proliferation)

Diagnosis:
 Calcific
tendinitis, FCU tendon on pisiform

Discussion: Calcific
tendinitis is a pathologic deposition of calcium hydroxyapatite crystal within
tendon. The frequently involving sites are rotator cuffs, biceps long and short
heads of shoulder, gluteal insertions on femoral greater trochanter, triceps
tendon on olecranon, common tendons on medial & lateral epicondyles of
humerus, FCU (flexor carpi ulnaris), FCR, ECU tendons in wrist, and longus
colli muscle anterior to C2 usually. There are known 4 phases of calcific
tendinitis as follows.

•       Precalcific

–      A portion of tendon undergoes
fibrocartilagenous transformation for variable reason such as vascular
insufficiency or mechanical insult

•       Formative

–      Calcification occurs and enlarges,
maybe symptomatic

•       Resorptive

–      Inflammation, macrophage absorb the
deposit

–      Severe symptom

–      Bone erosion, bone marrow edema,
mimicking infection or tumor

•       Postcalcific

–      Fibroblast restore the normal tendon
collagen pattern

Among them,
in formative and resorptive phases, it may be symptomatic due to inflammation,
especially in the resorptive phase. During those phases, the calcification is
less dense, shows fuzzy margin in plain radiographs and US exam, without
acoustic shadowing.

References:

1.    
Daniel et
al. Calcific tendinitis: a pictorial review. CARJ 2009;60:293-272

2.    
Curtis et
al. Calcium Hydroxyapatite Deposition Disease. RadioGraphlcs 1990; 10:1031-1048