Spontaneous pneumomediastinum in a dermatomyositis patient with anti-melanoma differentiation-associated gene-5 antibody and interstitial lung disease despite an initial response to immunosuppressant.

We report a 24-year-old man with anti-melanoma differentiation-associated gene-5 (MDA5) antibody-positive dermatomyositis (DM) and interstitial lung disease (ILD) who developed spontaneous pneumomediastinum. By comparing serial thoracic high-resolution computed tomography scans, we demonstrated the distinct time course showing a paradoxical occurrence of pneumomediastinum despite a radiological improvement of ILD. Our case shows that pneumomediastinum in DM can occur regardless of associated ILD and it is a serious complication that should be considered in DM patients presenting with pulmonary manifestations. Cutaneous vasculopathy may be associated with pneumomediastinum and could potentially be a useful indicator of future disease.

Diffusion-weighted imaging versus short tau inversion recovery sequence: Usefulness in detection of active sacroiliitis and early diagnosis of axial spondyloarthritis.

OBJECTIVE: To compare the utility of Diffusion weighted imaging (DWI) with short tau inversion recovery (STIR) sequence in the diagnosis of early axial spondyloarthritis (SpA). METHODS: Three hundred and five patients with chronic back pain were recruited consecutively from 3 rheumatology centers. Clinical, radiological and blood parameters were recorded. Patients with back pain duration no more than 3 years were classified as having early disease. STIR sequence and DWI of the sacroiliac joints were obtained and assessed using the Spondyloarthritis Research Consortium of Canada (SPARCC) method. The Assessment in Spondyloarthritis international Society definition was used to define positive STIR and DWI. Results were compared to expert diagnosed axial SpA. RESULTS: When compared to STIR sequence, DWI had similar sensitivity (STIR 0.29, DWI 0.30) and specificity (STIR 0.97, DWI 0.92) in diagnosing sacroiliitis. However, STIR sequence had better reliability (STIR 0.78, DWI 0.61). In early disease group, DWI was not better than STIR sequence in detecting active sacroiliitis (sensitivity DWI vs STIR: 0.34 vs 0.36; specificity DWI vs STIR: 0.93 vs 0.93; positive predictive value DWI vs STIR: 0.92 vs 0.92; negative predictive value DWI vs STIR: 0.36 vs 0.37). Using the Assessment in SpondyloArthritis international Society (ASAS) classification criteria, 67/98 patients with early disease (sensitivity 0.91 specificity 0.90) and 221/305 overall (sensitivity 0.90; specificity 0.92) were classified as axial SpA. Among the expert diagnosed axial SpA patients who did not meet the ASAS criteria, only 2 had positive DWI. CONCLUSION: DWI and STIR have similar sensitivity in diagnosing axSpA in early disease. However, the use of DWI is limited by poorer reliability when compared with STIR.