title: Frictional asymptomatic darkening of the extensor surfaces.
authors: Robert T
authors: RT
authors: Brodell
authors: Smita
authors: S
authors: Krishnamurthy
mesh_terms: D017276:Friction; D006801:Humans; D017495:Hyperpigmentation / Q000209:etiology*; D011656:Pulmonary Emphysema / Q000150:complications*; D013848:Thigh