Clinical Features
Pulmonary involvement by amyloid is rare, and with few exceptions, the amyloid is AL type.
3,4 The histologic manifestations of pulmonary amyloidosis include (1) diffuse alveolar septal amyloidosis, (2) nodular pulmonary amyloidosis, and (3) tracheobronchial amyloidosis.
Diffuse alveolar septal amyloidosis is usually systemic and present in patients with primary amyloidosis with or without associated plasma cell disorder and rarely with senile, secondary, or hereditary amyloidosis or in patients with renal failure on long-term hemodialysis.
3,5 Typically, lung involvement is an incidental finding as these patients rarely manifest
pulmonary symptoms. However, in a small subset of patients, diffuse alveolar septal amyloidosis presents with no extrapulmonary involvement, thus representing a form of localized amyloidosis.
6 In this clinical context, patients present mainly with a clinical picture of interstitial lung disease. Therefore, these patients primarily complain of progressive shortness of breath and show restriction on pulmonary function tests. In rare cases, the amyloid deposition is predominantly vascular, and patients have clinical findings of pulmonary hypertension or diffuse alveolar hemorrhage.
7 If the amyloid extends to the pleural surface, the clinical picture is dominated by recurrent chronic pleural effusions.
Nodular pulmonary amyloidosis is the most common form of pulmonary amyloidosis, a localized process to the lung, historically referred to as benign amyloidoma.
3 Nodular pulmonary amyloidosis has been described in association with low-grade lymphomas, mainly marginal zone lymphomas of mucosa-associated lymphoid tissue (MALT).
8 A recent study suggests that nodular pulmonary amyloidosis is part of a spectrum of lymphoproliferative disorders.
9 Patients with nodular amyloidosis present in their sixth decade (range 48 to 80) and have no sex predilection. Some patients present with a history of autoimmune disease such as Sjögren syndrome or prior MALT lymphoma. The nodules are usually discovered incidentally and the clinical differential diagnosis of granulomatous or metastatic disease considered. In most patients, the process remains localized without evidence of a systemic process.
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Tracheobronchial amyloidosis is rare.
3 As the name implies, amyloid is confined to the tracheobronchial tree and may extend to the larynx. Patients are usually in their fifth to sixth decade (reported age range 35 to 85 years). The association of tracheobronchial amyloidosis with Sjögren syndrome has been reported.
11 Patients, when symptomatic, usually present with stridor, wheezing, hemoptysis, or recurrent pulmonary infections.
