Nodular Amyloidosis

Nodular amyloidosis is a rare lesion that generally presents incidentally in adults as a 1- to 4-cm slow-growing nodule. The nodules are typically irregular, hard, and yellow-gray, consisting of intrapulmonary masses of extracellular amyloid.

Cytologic Features

Acellular globules of amorphous material.
Generally paucicellular background.

Histologic Features

Amorphous sheets of eosinophilic extracellular amyloid.
Characteristic foreign-body giant-cell reaction accompanying the amyloid deposits.
Lymphoplasmacytic infiltrate is generally present, most prominent at the periphery.
Ossification and calcification occur frequently.
Apple-green birefringence on Congo red stain.