Enhanced MR imaging of the shoulder, and sternoclavicular and acromioclavicular joint arthritis in primary hemochromatosis

Hemochromatosis is an autosomal recessive disease with a prevalence of about 4 cases per 1,000 in Europe and North America. One of every eight Americans is a heterozygous carrier. The heterozygous state is rarely symptomatic. Hemochromatosis is less common in black people of any ethnic origin [1].

Hemochromatosis is similar to CPPD crystal deposition disease/pseudogout. It produces radiographic changes similar to osteoarthritis, such as cartilage and joint narrowing, and chondrocalcinosis.

The development of arthropathy in hemochromatosis patients appears to be intimately related to the deposition of small amounts of iron or hemosiderin within the affected joints. Ferric salts promote the formation and deposition of intra-articular calcium pyrophosphate crystals by inhibiting the activity of synovial pyrophosphates and decreasing the clearance of intra-articular immune complexes, by inhibiting the activity of synovial reticuloendothelial cells. This often manifests as chondrocalcinosis on radiographs (Fig. 1a, b). These effects, reflecting systemic iron excess, appear to trigger the development of acute joint inflammation in the affected patients [4].

A pattern of arthritis involving the metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints of the second and third fingers suggests hemochromatosis [1] but the wrists, hips, knees and shoulders can also be involved [7]. However; its appearance can be indistinguishable from osteoarthritis, gout or pseudogout. Because iron overload disease underlies many cases of chondrocalcinosis, a radiographic finding of chondrocalcinosis should prompt evaluation for hemochromatosis [1].

Other radiologic findings include cystic joint erosion, hook-like osteophytes, joint space narrowing and sclerosis [7]. Occasionally, joint cartilage is rust-colored, but this finding is not specific. Many people with joint replacement, particularly at younger ages, have hemochromatosis that is often unrecognized [1]. Our case also had bilateral hip joint involvement followed by total hip replacement at age 59 years (Fig. 1b).

Roan et al. [8] believed that GLOM can be caused by torn labral fragment, loose body, prominent middle glenohumeral ligament (MGHL) and dislocated biceps tendon.

Parmar et al. described a GLOM lesion as an interesting appearance of the anterior labral tear that had retracted superiorly. He also stated that GLOM represents a dark, rounded mass of tissue on proton density and T2-weighted images [3, 9]. However, our patient had enlargement of the anterior glenoid labrum (GLOM) due to hemochromatosis deposit (Fig. 3, arrow).

Huaux et al. [10] noted that the pattern of the hemochromatosis arthropathy is characterized mainly by articular chondrocalcinosis (ACC) and subchondral arthropathy. Jäger et al. [11] reported that 30% of patients with hemochromatosis have chondrocalcinosis and 50% have degenerative osteoarthritis. Radiograph of the left shoulder in our patient showed calcific tendinopathy and linear chondrocalcinosis at the articular surface of the humeral head. AP view of the pelvic also showed chondrocalcinosis of the symphysis of pubis (Fig. 1a, b).

Schmid et al. reported that the MR imaging appearance of three ankle joints with primary hemochromatosis, containing extensive subchondral cyst formation, subchondral sclerosis, and joint space narrowing [3, 6]. In our case MRI of shoulder shows a 1 cm erosion of humeral head (Fig. 2).

It is remarkable that the severity of osteoarthritis has not been found to correlate with the amount of intra-articular iron or total iron stores [3]. Moore et al. referred to susceptibility artifact due to iron deposition in the wrist joint [3, 5]. MR imaging has been used for detection and quantification of iron overload in the liver, spleen, and pancreas [3], as the strong paramagnetic properties of the stored iron cause a significant decrease in T2 relaxation times of the tissues. Iron accumulation in the synovium, cartilage or synovial fluid is considerably less pronounced than that of the solid viscera and is well below the threshold that can be reliably detected with MR imaging [3]. In a previous study, MR imaging failed to confirm the presence of intra-articular iron in the knee joint in ten patients with primary hemochromatosis [3]. However, in our patient, signal loss associated with iron deposit was diffuse and seen in the cartilage, synovial tissue and tendon on gradient sequences, which are considered to be the most susceptible to the paramagnetic properties of iron (Fig. 3) [3].

In conclusion, we described the MRI and radiographic findings of multiple joint involvement in a patient with primary hemochromatosis (Figs. 4, 5, 6).