128 Hemochromatosis

Hemochromatosis

Anthony G. Ryan and Peter L. Munk

Clinical Presentation

A 60-year-old man presented with bilateral painful hands.

Figure 128A

An anteroposterior radiograph of both hands (Fig. 128A) shows joint space reduction affecting the metacarpophalangeal, radiocarpal, and interphalangeal joints; diffuse osteopenia; and prominent hooked osteophytes on the radial aspect of the second and third metacarpals, the heads of which are enlarged by the presence of the osteophytes. Variable lucencies, marginated by thin, sharply defined rims of sclerosis, are evident within the metacarpal heads. Chondrocalcinosis is evident in the triangular fibrocartilage bilaterally. The scapholunate interval is of normal size.

Diagnosis

Hemochromatosis arthropathy.

Differential Diagnosis

Pseudogout (should demonstrate no evidence of arthropathy)
Psoriatic arthritis (should have the typical skin and nail changes with this degree of cartilaginous and bony change)
Osteoarthritis (affects predominantly the distal joints of the hands)
Rheumatoid arthritis
Gout (in which chondrocalcinosis may also be seen)

Discussion

Etiology

Hemochromatosis may occur as a primary or secondary (acquired) condition.

The primary, idiopathic form is transmitted as an autosomal recessive trait, with only homozygotes demonstrating the clinical condition, or via indeterminate inheritance (e.g., there is an abnormal iron-loading gene present in thalassemia and sideroblastic anemia, resulting in increased iron absorption with a normal dietary load).

Acquired hemochromatosis occurs secondary to

Excessive iron absorption in anemias, myelofibrosis, and portacaval shunt
Exogenous administration of iron, multiple blood transfusions, porphyria cutanea tarda, and drinking beer brewed in iron vessels

Both primary and secondary causes result in deposition of excessive iron in the liver, pancreas, spleen, gastrointestinal tract, kidney, gonads, heart, and endocrine glands, resulting in fibrosis, which leads to eventual organ failure.

Pathophysiology

Iron deposition in the synovium leads to an arthropathy in 30 to 50% of cases. Synovitis is also caused and/or exacerbated by secondary calcium pyrophosphate deposition (CPPD), leading to chondrocalcinosis, most frequently found in the triangular fibrocartilage of the wrist, the menisci, the anulus fibrosus, the ligamentum flavum, the symphysis pubis, the Achilles’ tendon, and the plantar fascia.

The calcification is due to deposition of calcium pyrophosphate crystals, perhaps resulting from iron inhibition of pyrophosphatase.