- Hypertrophic osteoarthropathy (HOA) is a clinical syndrome of clubbing of the fingers and toes, enlargement of the extremities, and painful swollen joints.
- HOA is characterized by symmetric periostitis involving the radius and fibula and, to a lesser extent, the femur, humerus, metacarpals, and metatarsals.
- The syndrome can be primary or secondary.
- Primary HOA (aka pachydermoperiostosis) is a rare familial autosomal dominant condition.
- About 3-5% of patients with HOA have primary HOA.
- The precise etiology of pachydermoperiostosis is unclear
- Pachydermoperiostosis usually occurs in adolescents, but it can affect prepubescents as well.
- Secondary causes of HPOA can be subdivided into pulmonary, pleural, cardiac, abdominal, and miscellaneous.
- Pleural causes include solitary fibrous tumor of the pleura and mesothelioma.
- Cyanotic heart disease with a right-to-left shunt is the only cardiac cause described.
- Pulmonary causes include lung cnacer; pulmonary tuberculosis; pulmonary abscesses; blastomycosis; bronchiectasis; emphysema; and Pneumocystis carinii infection in patients with AIDS, Hodgkin disease, metastases, or cystic fibrosis.
- Abdominal causes include liver cirrhosis, ulcerative colitis, Crohn's disease, amebic and bacillary dysentery, gastrointestinal tract polyposis, gastrointestinal tract neoplasms (gastric and pancreatic), lymphoma of the bowel, Whipple disease, and biliary atresia.
- In the US: Pachydermoperiostosis is rare
- HOA occurs in approximately 5% of patients with lung cancer and 50% of patients with pleural mesothelioma.
 Imaging Findings
- The predominant radiographic periostitis, which is depicted as symmetric osseous thickening.
- Periostitis mostly affects the tubular bones of the limbs, especially the radius, ulna, tibia, and fibula, although the pelvis, carpus, tarsus, metacarpals, metatarsals, and phalanges can be involved.
- Periosteal proliferation is usually shaggy and associated with irregular excrescences and diaphyseal expansion.
- Secondary hypertrophic osteoarthropathy
- Usually involves diaphyseal and metaphyseal periostitis.
- Periosteal proliferation is usually single or laminated and regular or irregular.
- Laminated periostitis may have an onionskin appearance.
- Periarticular soft tissue swelling, clubbing, and clinical and radiologic features of an underlying primary lesion are often depicted.
- Digital clubbing associated with soft tissue swelling may be depicted on plain radiographs.
 Nuclear medicine
- Bone scan with technetium Tc 99m–labeled diphosphonate shows changes of HOA early and with sensitivity greater than that of other methods.
- Isotope uptake is symmetrically increased in the tubular bones along the cortical margins of the diaphysis and metaphysis.
- Uptake may be irregular, or it may create a double-stripe or parallel-track sign.
- Periarticular radionuclide uptake may be increased as a result of associated synovitis.
Patient #1: Hypertrophic osteoarthropathy in a patient with thymic carcinoma
 See Also
 External Links
- E-medicine Hypertrophic osteoarthropathy article.