Hypertrophic osteoarthropathy as a paraneoplastic syndrome is most commonly associated with which malignancy?
A. Hepatocellular carcinoma
B. Renal cell carcinoma
C. Gastric cancer
D. Lung cancer (especially adenocarcinoma)
Explanation
Hypertrophic Osteoarthropathy (HOA) as a Paraneoplastic Syndrome
Key Point
Hypertrophic osteoarthropathy is a paraneoplastic syndrome characterized by clubbing, periosteal new bone formation, and arthralgia. Lung cancer, particularly adenocarcinoma, is the most common malignancy association.
High-YieldNEET PG
HOA occurs in 5–12% of lung cancer patients, with adenocarcinoma > squamous cell carcinoma > SCLC. It is rare in other malignancies but can occur with gastric, breast, and ovarian cancers.
Pathophysiology
The exact mechanism is unclear but involves:
1.
Megakaryocyte embolization theory: tumor produces vascular endothelial growth factor (VEGF) and other angiogenic factors → megakaryocytes bypass the lungs → lodge in peripheral vessels → release growth factors (platelet-derived growth factor, transforming growth factor-β) → periosteal proliferation and soft tissue edema.
2.
Vagal afferent theory: vagal stimulation from lung tumor → reflex vasodilation and bone remodeling.
Clinical Features
Table
Feature
Description
Clubbing
Bulbous enlargement of fingertips and toenails (most visible sign)
Periosteal new bone formation
Painful, symmetric, affects long bones (tibia, fibula, radius, ulna)
Arthralgia/arthritis
Wrists, knees, ankles; may precede malignancy diagnosis
Soft tissue edema
Hands, feet, face (puffy appearance)
Skin changes
Thickened, oily skin; hyperhidrosis
Clinical Pearl
HOA may regress after successful tumor resection or treatment, making it a useful marker of treatment response.
Mnemonic
HOA = Hypertrophic Osteoarthropathy = Adenocarcinoma (lung) association.
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