LC‐MS/MS and immuno‐electron subtyping combined with genetics show that OSMR mutations cause amyloid deposition of keratins 5/14 in familial primary localized cutaneous amyloidosis.

LMD-MS/MS analysis of several dermal microdissected amyloid deposits demonstrated high spectra for KRT5/14 heterodimers, along with the amyloid signature proteins. Spectra of other known amyloid proteins were not detected; notably, no spectra for light chain immunoglobulins were detected, ruling out AL amyloidosis. gl The Chinese family included three symptomatic members (II.8, II.9 and II.10), who complained of pruritic lesions, highly suggestive of lichen amyloidosis, over arms, legs and back. LC-MS/MS and immuno-electron subtyping combined with genetics show that OSMR mutations cause amyloid deposition of keratins 5/14 in familial primary localized cutaneous amyloidosis. [Extracted from the article]