Thyroid Acropachy

General Considerations

• One of the extra-thyroidal manifestations of autoimmune thyroid disease
• Occurs in about 1% of patients with Grave’s Disease
• Almost always associated with ophthalmopathy
• May be associated with thyroid dermopathy (myxedema)
• Chronology of findings is usually thyroid dysfunction, ophthalmopathy, dermopathy and then acropachy
• Most patients are also smokers
• Can occur in both euthyroid and hypothyroid patients and usually follows the manifestations of thyroid dysfunction itself
  • May occur after radioactive treatment for hyperthyroidism

Clinical Findings

• Asymptomatic in most patients
• Clubbing
• Swelling of the fingers and toes
• Joint pain, especially small joints
• High thyroid stimulating antibody titers

Imaging Findings

• Clubbing of the fingernails and toenails
• Swelling of the fingers and toes
• Solid periosteal new bone formation
  • May be thin or thick
• Sometimes spiculated or lacy in appearance
• Involves the metacarpals, proximal and middle phalanges of the hand, metatarsals and proximal phalanges of the toes
• Usually bilateral and symmetric, but may be asymmetric, sometimes involving a single digit
• Radionuclide bone scans may show radiotracer uptake before findings visible on conventional radiographs

Differential Diagnosis

• Hypertrophic osteoarthropathy
  • Usually involves long bones, but spares the ends
• Symmetric
• Pachydermoperiostitis
• Idiopathic variety of hypertrophic osteoarthropathy
• Younger
• Involves forearm, tibia and fibula
• Does not spare the ends of bones
• Hypervitaminosis A
• Generalized periostitis

Treatment

• Immunosuppressive therapy and steroid administration for thyrotoxicosis

Prognosis

• Remission of findings may occur in long-term

Thyroid Acropachy. Thick, wavy periosteal reaction is seen along the shafts
of the 1st through 4th metatarsals bilaterally (white circles).
For this same photo without the arrows, click here
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Thyroid Acropachy: Report of 40 Patients Treated at a Single Institution in a 26-Year Period. V Fatourechi, DDF Ahmed, and KM Schwartz. The Journal of Clinical Endocrinology & Metabolism 87(12):5435–5441 

Thyroid Acropachy. O Batal and SF. Hatem. Orthopedics January 2008;31(1):2.