Final Diagnosis: Mediastinal amyloidoma

Right chest mass, core biopsy - amyloid with areas of focal calcification and an otherwise acellular specimen.

Comments:

Immunohistochemical stains for kappa and lambda are non contributory as there are insufficient plasma cells for staining. Congo Red stains show that the material is apple green birefringent when viewed under polarized light. EM shows the charecteristic beta pleated sheets of amyloid.