What is hypertrophic osteoarthropathy (HOA)?
HOA is a syndrome that includes (1) clubbing of fingers (Hippocratic fingers) and toes, (2) periostitis of tubular bones, and (3) arthritis with a noninflammatory synovial fluid. Primary HOA (pachydermoperiostosis) is autosomal dominant, appears during childhood mostly in males (M:F ratio, 9:1), and is characterized by clubbing, skin hypertrophy (pachyderma), coarse facial features, seborrhea, and hyperhidrosis. Secondary HOA may be limited to clubbing or include the full spectrum. The generalized form is most often associated with intrathoracic malignant neoplasms (primary or secondary pulmonary tumors) in 90% of cases. It also occurs in patients with other malignancies (hepatic, gastrointestinal, peroral endoscopic myotomy syndrome), chronic infections (lung, subacute bacterial endocarditis, human immunodeficiency virus, others), cystic fibrosis, congenital cyanotic heart disease, inflammatory bowel disease, cirrhosis, Graves’ disease, or on certain drugs (voriconazole). The localized form of HOA has been associated with hemiplegia, aneurysms, infective arteritis, and patent ductus arteriosus. The clinical course of secondary HOA is determined by the underlying primary disease. Zoledronic acid can help symptoms but successful treatment of the primary disease will lead to resolution of secondary HOA. Platelet/endothelial cell activation with the release of vascular endothelial growth factor and platelet-derived growth factor appears to play a key role in the etiology of HOA, which may be targets for future treatment.
