Hypertrophic OsteoarthropathyDz

Synonyms: HOA, Acropachy, familial idiopathic hypertrophic osteoarthropathy, pachydermoperiostosis, Marie-Bamberger syndrome.

ICD-9 Code: 731.2.

Definition: Hypertrophic osteoarthropathy is a syndrome characterized by proliferation of skin and bone in the distal extremities. The complete hypertrophic osteoarthropathy syndrome includes clubbing of the fingers and toes, periostitis (with new bone formation on long bones), and arthritis. Not all patients have all manifestations.

Etiology: The primary form is of unknown etiology, but most likely has a genetic basis. Secondary forms are associated with pulmonary (cystic fibrosis, pulmonary fibrosis, cancer, chronic infection), cardiac (cyanotic congenital heart disease, patent ductus arteriosus, bacterial endocarditis), GI (inflammatory bowel disease, cancer, cirrhosis), or malignant disorders (lymphoma). Mechanisms underlying these associations are unknown.

Pathology: Long bones show various stages of new bone formation on cortical surfaces. Clubbed digits show increased numbers of fibroblasts, and collagenous tissue and synovial membranes may have proliferative features.

Demographics: The primary genetic form appears in children or young adults. Secondary forms are more likely to be seen in older patients.

Cardinal Findings: Clubbed digits (fingers and toes) have been described as having a drumstick-like appearance, with softening and mobility of the nail bed. Involvement of long bones may produce severe, incapacitating, or deep bone pain. Areas affected by periostitis are often painful and may be associated with overlying warmth or edema. Arthralgia or arthritis is often symmetric and involves the metacarpophalangeal, wrist, elbow, knee, and ankle joints. Joints may be warm and swollen with an effusion.

Uncommon Findings: Thickening of the skin (pachydermia) may alter facial features and produce coarse or leonine features. Pachydermia is uncommon in the secondary forms of hypertrophic osteoarthropathy. Thyroid acropachy, a rare manifestation of hyperthyroidism, may be associated with exophthalmos and pretibial myxedema.

Diagnostic Tests: Laboratory tests are not specific for hypertrophic osteoarthropathy but may reflect the underlying malignant or infectious disorder. The ESR is often elevated in secondary hypertrophic osteoarthropathy. Synovial fluid is often noninflammatory (WBCs <2,000 cells/mm3).

Imaging: Radiographs of long bones show new bone formation (periostitis), especially in the extremities. Periostitis is common in the distal tibia or fibula, radius, or ulna. It is less common in the phalanges. Acroosteolysis may be seen; joint space narrowing or erosions are absent. Bone scanning may be useful.

Diagnostic Criteria: Digital clubbing and periostosis of tubular bones are required for the complete syndrome. Three incomplete forms are defined: (a) clubbing alone; (b) periostosis without clubbing but with any of the systemic illnesses associated with hypertrophic osteoarthropathy; and (c) pachydermia associated with any of the minor manifestations, including synovial effusions.

Differential Diagnosis: Skin resembles scleroderma. See causes for periostitis.

Therapy: Clubbing alone requires no specific treatment. Secondary forms respond to removal or treatment of underlying thoracic disease. NSAIDs are used to treat symptoms.

Prognosis: In secondary forms, the outcome is dictated by the underlying disorder.

BIBLIOGRAPHY

Martinez-Lavin M, Matucci-Cerinic M, Jajic I, et al. Hypertrophic osteoarthropathy: consensus on its definition, classification, assessment and diagnostic criteria. J Rheumatol 1993; 20:1386–1387.