Pulmonary Pathology Online
Pathology of Nodular Pulmonary Amyloid (Pulmonary Amyloidoma)
a spectrum of diseases associated with an abnormal extracellular
deposition of amyloid.
Amyloid deposition can occur in association with inflammatory, hereditary, or neoplastic entities.
The respiratory system is involved in approximately 50% of patients with amyloidosis.
In the lung amyloid deposition may be localized or diffuse and may have a variety of appearances.
On average, affected patients are in the 6th decade of life.
Nodular amyloidosis is usually asymptomatic and thus found incidentally.
Atelectasis and secondary bronchiectasis due to obstruction of a bronchus have been reported.
Three forms of Primary pulmonary amyloidosis:
i) Tracheobronchial ii) Nodular parenchymal, and iii) Alveolar septal.
Tracheobronchial amyloidosis is the most frequent manifestation of pulmonary amyloidosis.
Nodular pulmonary amyloidosis is a limited form of amyloidosis.
It is characterized by single or multiple intrapulmonary nodules or masses and is also known as amyloidoma.
Amyloidoma usually occur in the lower lobes.
These may be mistaken as a tumour.
The lesion may calcify or undergo osseous metaplasia.
Resection of these nodules is both diagnostic and curative.
Usually nodular pulmonary "amyloidomas" are characterized by a benign course.
According to recent studies the association of nodular pulmonary amyloidoma with autoimmune disease and lymphoma indicate the majority of these lesions relate to an underlying lymphoplasmacytic neoplasm in the spectrum of MALT lymphoma.
Despite its localized nature, tracheobronchial amyloid deposition may be asymptomatic or may result in significant morbidity due to obstructive phenomena.
Pulmonary amyloidosis associated with primary systemic amyloidosis generally presents as a diffuse interstitial pattern with or without pleural effusion.
Imaging of nodular amyloidosis shows solitary or multiple nodules with a smooth or lobular contour.
Nodules are often seen in a subpleural or peripheral location .
Calcification may occur in up to 50% of nodules seen at CT scan.
Gross examination: Amyloid nodules are either yellow, gray, or pale tan.
The nodules range in size from 0.6 to 15 cm.
Larger lesions may cavitate or exhibit hemorrhage, necrosis, fibrosis, or calcification.
Amyloid appears as an amorphous sheet of eosinophilic extracellular material that surrounds vessels.
Differential diagnosis: Primary or metastatic neoplasms.
Amyloid-like nodules should be distinguished from nodular amyloidosis and, in some patients, might represent a localized form of light-chain deposition.
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