Hypertrophic osteoarthropathy associated with lung cancer: Possible links among hypoxia‐inducible factor‐1α, vascular endothelial growth factor, and hypervascularization

Hypertrophic osteoarthropathy (HOA) is a paraneoplastic syndrome, the exact pathogenesis of which remains to be elucidated. The case of a 69‐year‐old man who developed intractably painful HOA secondary to lung cancer is presented. Contrast‐enhanced computed tomography of the chest showed an 80‐mm solid nodule with a large low‐density area. The patient was diagnosed as having stage IIIA undifferentiated non–small cell lung cancer. The combination of carboplatin and paclitaxel with bevacizumab reduced tumor size and plasma vascular endothelial growth factor (VEGF) levels, relieving his leg pain. On immunohistochemical examination, lung cancer cells were positive for VEGF. A hypoxic tumor microenvironment may have caused some lung cancer cells to express hypoxia‐inducible factor‐1α, which contributed, at least in part, to the production of VEGF. The deep dermis vessels showed proliferation in the shin, with their thickened walls positive for VEGF. These findings may encourage investigators to explore novel management strategies for painful HOA.