Pulmonary Amyloidosis: Diverse Clinical and Histopathological Manifestations - A Series of Five Cases

Abstract

Pulmonary amyloidosis, a rare condition caused by the abnormal deposition of protein fibrils, most often the AL (light chain) type, within the lung, frequently presents a diagnostic challenge. Its clinical manifestations often resemble more prevalent lung diseases like cancer or infections. A crucial step is to differentiate between disease limited to the respiratory system and widespread systemic involvement, as this guides the appropriate treatment. This report provides a retrospective analysis of five histologically confirmed cases of pulmonary amyloidosis, detailing their presenting clinical features, radiological findings, microscopic tissue characteristics, immunohistochemical analysis, and results from systemic evaluations. Our patient group, comprising three males and two females aged between 38 and 67 years, presented with varied initial symptoms: three had lung masses, one exhibited pleural effusion with concurrent liver disease, and another was being treated for tuberculosis. Microscopic examination revealed discrete amyloid nodules in three cases, diffuse interstitial deposition in one, and a pleural based accumulation in another. Immunohistochemical studies confirmed AL-type amyloid in three cases, AA-type in one, while the specific amyloid type remained undetermined in a fifth case. A confirmed diagnosis of systemic amyloidosis was made in only one patient. In one instance, nodular pulmonary amyloidosis occurred alongside fungal colonization. Pulmonary amyloidosis often poses a diagnostic conundrum in lung pathology. While localized nodular forms generally follow a benign clinical course, diffuse patterns necessitate a thorough systemic evaluation, even when serological indicators are negative. Advanced techniques like mass spectrometry and extensive imaging are becoming more vital for accurate subtyping and informed treatment decisions.