Hypertrophic osteoarthropathy

Hypertrophic osteoarthropathy(HOA, hypertrophic pulmonary osteoarthropathy, HPO, 비후성 골관절증)은 사지 말단의 피부와 long bone의 periosteal tissue의 비정상적인 증식에 의해 digital clubbing, periostosis of tubular bones, and synovial effusion을 특징적으로 보이는 질환으로, 일차성과 이차성으로 나누며, lung cancer나 다른 질환에 의한 이차성이 대부분(95~97%)을 차지한다.

Clinical feature

• The most common cause of secondary HOA: non–small cell lung carcinoma(NSCLC).
  • The incidence of HOA in lung cancer: 4~17%
  • other causes: not just thoracic but extrathoracic diseases
    • cystic fibrosis, cirrhosis and inflammatory bowel disease and so on.
• Primary HOA: rare hereditary disease, usually with an early onset during childhood or adolescence.

Imaging feature

Radiography and CT

• Periostosis: imaging hallmark, manifests along the shafts of tubular bones and usually spares the epiphyses in the earliest phases.
  • Epiphyseal involvement is more common in primary HOA
  • Symmetric and widely distributed osseous involvement is a typical finding in primary and generalized secondary HOA, given its systemic mediation.

MR imaging

• Periosteal reaction: typically exhibits low-to-intermediate signal intensity on T1-weighted images and low signal intensity on T2-weighted images

Bone scintigraphy

• More sensitive than radiography alone.
  • often diagnosed serendipitously in patients with known malignancy.
• Symmetrically increased tracer uptake at the periosteum in a linear fashion along the cortical margins of the diaphysis and metaphysis of the long tubular bones(the tram line or double stripe sign)

Differential diagnosis

multifocal periosteal reaction을 일으키는 질환들

• Thyroid acropachy
• Voriconazole-induced periostitis
• Venous insufficiency
• Leukemia and Lymphoma
• Hypervitaminosis A
• Progressive diaphyseal dysplasia

Treatment

• Treatment of the underlying cause
  • Prognosis and mortality of secondary HOA are related to the underlying disease itself.

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