Objective: To observe the impact of plateau sunlight radiation on skin thickness and hardness with high frequency ultrasound and shear wave elastography (SWE). Methods: Totally 30 volunteers from plateau areas (plateau area group) and 48 volunteers from non-plateau areas (non-plateau area group) were enrolled. Skin thickness and skin hardness of right middle finger, right forearm, anterior chest wall and abdominal wall were measured with high frequency ultrasound and SWE and then compared between two groups. Diagnostic test of the above parameters which showed significant differences were performed, and ROC curve were drawn. Results: Skin thickness, maximum elastic value (Emax), average elastic value (Emean), minimum elastic value (Emin) and standard deviation (Esd) of right middle fingers, skin Emax, Emean, Emin of right forearms and anterior chest walls, skin Emax, Emean, Emin, Esd of abdominal walls of plateau area group were all higher than those of non-plateau area group (all P<0.05), while skin thickness of anterior chest wall and abdominal wall of plateau area group were lower than those of non-plateau area group (both P<0.05). Skin Emax, Emean, Emin of abdominal wall had the largest AUC in diagnosis of plateau skin, which were all >0.95. Taken skin Emax=13.30 kPa, Emean=12.45 kPa, Emin=11.50 kPa of abdominal wall as cut off values, the sensitivities in diagnosis of plateau skin were all 100%, and specificities were 85.40%, 87.50% and 85.40%, respectively. Conclusion: Plateau sunlight radiation lead to changes of skin thickness and make the skin harden. Skin Emax, Emean, Emin of abdominal wall have the highest diagnostic efficiencies.

ObjectiveTo explore the value of differential diagnosis between pigmented villonodular synovitis (PVNS) and rheumatoid arthritis (RA) in active stage with clinic and ultrasound. MethodsWe analyzed retrospectively the characters of clinic and ultrasound of sixteen patients with PVNS and sixteen patients with rheumatoid arthritis inactive stage.ResultsIn aspects of patient’s age (T=185), pain scores (T=136) history of trauma (P=0.029), functionally uncompensated conditions (P=0.001) type (P=0.000) and sum (P=0.000) of involved joints、bright spot-echoes in hydrops (P=0.001) tendons nearby involved (P=0.001) and the Adler’s grade of Doppler ultrasound blood flow (P=0.009), the differences between PVNS and RA in active stage had statistical significance (P<0.05). Clinic characters: patients with PVNS were younger, often had a history of trauma. But patients with RA in active stage had a higher pain score and functionally uncompensated condition. Ultrasound characters: big and single joints were often involved in patients with PVNS, and tiny bright spot echoes could be detected in hydrops. Instead, big and small, multiple joints, tendons nearby were often involved in patients with RA, who had a higher ratio of gradeⅢ Doppler ultrasound blood flow. And in aspects of sex, the presence of hydrops and synovium thickness, the differences between the two had no statistical significance (P>0.05).ConclusionThe clinical characters including Patient’s age, pain scores, history of trauma, functionally uncompensated conditions, and the characters of ultrasound including type and sum of involved joints, bright spot echoes in hydrops, tendons nearby involved and the Adler’s grade of Doppler ultrasound blood flow, are helpful for the differential diagnosis of PVNS and RA in active stage.