Assessment of Treatment Response by Bone SPECT-CT in a Case of Dermatomyositis with Calcinosis Cutis.

Calcinosis of soft tissue is a rare but known complication of dermatomyositis (DM), mostly associated with juvenile DM and rare in adult DM. Bone scan with Tc-99m Methylene diphosphonate is useful in disease mapping and has high sensitivity to know the extent of calcinosis. However, there is scanty literature available on the utility of bone scan in treatment response evaluation in DM. Rituximab has been found useful in adult DM with calcinosis unresponsive to conventional treatment. We describe an interesting case showing partial response to rituximab on bone scan with single-photon emission tomography-computed tomography.