Medical condition
The shoulder pad sign is an enlargement of the anterior shoulder due to amyloid deposition in periarticular soft tissue.[1][2][3] This type of infiltration is not common, but it is pathognomonic for AL amyloidosis.[1][2][3]
Analysis of the amyloid protein has demonstrated that it has a kappa III Ig light chain structure.[1] The variable region of kappa III amyloid proteins may show an increased likelihood of depositing in soft tissue.[1]
References