Anatomic Pathology / AMYLOID-LIKE PULMONARY NODULES

Amyloid-like pulmonary nodules have been described in patients with systemic light-chain deposition disease, but their significance in other clinical contexts is unknown. We examined biopsy specimens of amyloid-like pulmonary nodules from 3 women without systemic light-chain deposition disease. Patient 1 (aged 62 years) had multiple pulmonary nodules and underwent 2 separate lung biopsies, the first showing nodules composed of κ light-chain deposits accompanied by low-grade lymphoplasmacytic lymphoma limited to the lung and the second, obtained after chemotherapy 9 months later, showing only residual nodules without persistent lymphoma. Patients 2 (aged 65 years) and 3 (aged 69 years) had asymptomatic solitary pulmonary nodules. In all cases, electron microscopic examination showed dense granular extracellular deposits without the fibrillary characteristics of amyloid. Amyloid-like nodules should be distinguished from nodular amyloidosis and, in some patients, might represent a localized form of light-chain deposition. Amyloid is a form of fibrillary protein that is deposited in the extracellular matrix and has characteristic physical, ultrastructural, immunophenotypic, and tinctorial properties.1 Pulmonary amyloidosis can take a variety of forms and traditionally is separated into nodular, tracheobronchial, and diffuse alveolar septal forms.2 Nodular pulmonary amyloidosis comprises single or multiple nodules characterized by central amyloid deposition associated with a minor inflammatory infiltrate of lymphocytes, plasma cells, and multinucleated histiocytes. Patients usually are asymptomatic and have no underlying systemic disease. The prognosis is excellent. Occasional reports have described amyloid-like nodules in which the eosinophilic proteinaceous deposits lack histochemical, immunophenotypic, and ultrastructural features of amyloid.3-5 Amyloid-like pulmonary nodules have been described in patients with systemic light-chain deposition disease (LCDD),6 but the significance of amyloid-like nodules in other clinical contexts is unknown. We describe amyloid-like nodules in 3 patients without systemic LCDD. Materials and Methods We searched the surgical pathology files of Mayo Clinic, Rochester, MN, and our own consultation files to identify patients with the diagnosis of “amyloid-like nodules.” All available slides from pathologic examination of tissue from patients identified as having amyloid-like nodules were reviewed. Paraffin section immunoperoxidase staining was performed in all cases by using a standard peroxidaseantiperoxidase technique ❚Table 1❚. Slides used for serum amyloid A and P proteins were first deparaffinized and then Anatomic Pathology / ORIGINAL ARTICLE Am J Clin Pathol 2004;121:200-204 201 201 DOI: 10.1309/3GECPW2402F6V8EK 201 © American Society for Clinical Pathology pretreated with 44% formic acid and rinsed in cool water. Tissue was retrieved from all paraffin blocks and processed in a standard manner for ultrastructural studies. Clinical information was obtained from medical records, pathology reports, and contributing pathologists.