Localized interstitial pulmonary amyloid: a case report and review of the literature

The spectrum of pulmonary amyloidosis

Amyloidosis is a disease caused by misfolded proteins that deposit in the extracellular matrix as fibrils, resulting in the dysfunction of the involved organ. The lung is a common target of Amyloidosis, but pulmonary amyloidosis is uncommonly diagnosed since it is rarely symptomatic. Diagnosis of pulmonary amyloidosis is usually made in the setting of systemic amyloidosis, however in cases of localized pulmonary disease, surgical or transbronchial tissue biopsy might be indicated. Pulmonary amyloidosis can be present in a variety of discrete entities. Diffuse Alveolar septal amyloidosis is the most common type and is usually associated with systemic AL amyloidosis. Depending on the degree of the interstitial involvement, it may affect alveolar gas exchange and cause respiratory symptoms. Localized pulmonary Amyloidosis can present as Nodular, Cystic or Tracheobronchial Amyloidosis which may cause symptoms of airway obstruction and large airway stenosis. Pleural effusions, mediastinal lymphadenopathy and pulmonary hypertension has also been reported. Treatment of all types of pulmonary amyloidosis depends on the type of precursor protein, organ involvement and distribution of the disease. Most of the cases are asymptomatic and require only close monitoring. Diffuse alveolar septal amyloidosis treatment follows the treatment of underlying systemic amyloidosis. Tracheobronchial amyloidosis is usually treated with bronchoscopic interventions including debulking and stenting or with external beam radiation. Long-term prognosis of pulmonary amyloidosis usually depends on the type of lung involvement and other organ function.

A rare etiology of pulmonary nodules

Introduction

Pulmonary nodules are a frequent finding on chest imaging studies, with differential including multiple benign entities, but malignancy is often also a concern. Computed Tomography (CT) and Fluorodeoxyglucose (FDG)-Positron Emission Tomography (PET) scans have improved the characterization of pulmonary nodules. However, many nodules remain indeterminate and require periodic monitoring. Here we report two nodular pulmonary amyloidosis cases as a rare etiology of enlarging pulmonary nodules with FDG avidity.

Case presentation

Case 1: 75-year-old woman with a history of asthma, emphysema, bronchiectasis, and a 48 pack-year smoking history was found to have subcentimeter groundglass pulmonary nodules in the right lower lobe (RLL). Follow-up imaging demonstrated an increased solid component of a RLL bulla associated with mild FDG uptake on PET scan. A CT-guided biopsy revealed amyloid deposition. Case 2: 77-year-old man with a history of interstitial lung disease, asbestos exposure, prior tobacco use, and atrial fibrillation treated with amiodarone was found to have a 1.6cm RLL nodule. Follow-up imaging identified an interval increase to 2.0cm associated with moderate FDG uptake on PET scan. Transthoracic biopsy identified amyloid deposition.

Discussion

Nodular pulmonary amyloidosis is a rare form of amyloidosis which may present as an enlarging pulmonary nodule with FDG avidity, raising concern for malignancy. A CT-guided biopsy is a safe way to establish a diagnosis. Recent studies have demonstrated an association between nodular pulmonary amyloidosis and marginal zone lymphomas, which warrants longitudinal follow-up for evolution to lymphoproliferative disorder.

The lung in amyloidosis

Amyloidosis is a disorder caused by misfolding of autologous protein and its extracellular deposition as fibrils, resulting in vital organ dysfunction and eventually death. Pulmonary amyloidosis may be localised or part of systemic amyloidosis.

Pulmonary interstitial amyloidosis is symptomatic only if the amyloid deposits severely affect gas exchange alveolar structure, thus resulting in serious respiratory impairment. Localised parenchymal involvement may be present as nodular amyloidosis or as amyloid deposits associated with localised lymphomas. Finally, tracheobronchial amyloidosis, which is usually not associated with evident clonal proliferation, may result in airway stenosis.

Because the treatment options for amyloidosis are dependent on the fibril protein type, the workup of all new cases should include accurate determination of the amyloid protein. Most cases are asymptomatic and need only a careful follow-up. Diffuse alveolar-septal amyloidosis is treated according to the underlying systemic amyloidosis. Nodular pulmonary amyloidosis is usually localised, conservative excision is usually curative and the long-term prognosis is excellent. Tracheobronchial amyloidosis is usually treated with bronchoscopic interventions or external beam radiation therapy.

Amyloidosis of the Lung

CONTEXT

-Amyloidosis is a heterogeneous group of diseases characterized by the deposition of congophilic amyloid fibrils in the extracellular matrix of tissues and organs. To date, 31 fibril proteins have been identified in humans, and it is now recommended that amyloidoses be named after these fibril proteins. Based on this classification scheme, the most common forms of amyloidosis include systemic AL (formerly primary), systemic AA (formerly secondary), systemic wild-type ATTR (formerly age-related or senile systemic), and systemic hereditary ATTR amyloidosis (formerly familial amyloid polyneuropathy). Three different clinicopathologic forms of amyloidosis can be seen in the lungs: diffuse alveolar-septal amyloidosis, nodular pulmonary amyloidosis, and tracheobronchial amyloidosis.

OBJECTIVE

-To clarify the relationship between the fibril protein-based amyloidosis classification system and the clinicopathologic forms of pulmonary amyloidosis and to provide a useful guide for diagnosing these entities for the practicing pathologist.

DATA SOURCES

-This is a narrative review based on PubMed searches and the authors' own experiences.

CONCLUSIONS

-Diffuse alveolar-septal amyloidosis is usually caused by systemic AL amyloidosis, whereas nodular pulmonary amyloidosis and tracheobronchial amyloidosis usually represent localized AL amyloidosis. However, these generalized scenarios cannot always be applied to individual cases. Because the treatment options for amyloidosis are dependent on the fibril protein-based classifications and whether the process is systemic or localized, the workup of new clinically relevant cases should include amyloid subtyping (preferably with mass spectrometry-based proteomic analysis) and further clinical investigation.

Amyloid-associated Cystic Lung Disease

BACKGROUND

Amyloid-associated cystic lung disease is rare. It can be associated with collagen vascular disease (CVD). We aimed to describe the clinical, radiology, and pathology findings of this entity.

METHODS

We reviewed the records of subjects having biopsy-proven pulmonary amyloidosis with cystic lung disease demonstrated at high-resolution computed tomography (HRCT). Demographic characteristics, association with CVD and lymphoproliferative disorders, pulmonary function, and pathology results were reviewed. HRCT appearance was analyzed for number, size, distribution, and morphology of cysts and nodules.

RESULTS

Twenty-one subjects (13 female, eight male; median age, 61 years) with cystic pulmonary amyloidosis were identified. The most common pulmonary function patterns were normal (42%) and obstructive (32%). The most common associated CVD was Sjögren syndrome (10 of 12). Nine subjects had no CVD. Cysts tended to be multiple (≥ 10 in 14 of 21, 67%), round (21 of 21, 100%), or lobulated (20 of 21, 95%); thin-walled (< 2 mm in 17 of 21, 81%); and of small (< 1 cm in 21 of 21, 100%) to moderate (1-2 cm in 17 of 21, 81%) size. Peribronchovascular (19 of 21, 90%) and subpleural (19 of 21, 90%) cysts were typically present. Seventeen (81%) subjects had lung nodules, which tended to be numerous (≥ 10 in 10 of 17, 59%; 4-9 in six of 17, 35%). At least one calcified nodule was present in 14 of 17 subjects (82%). Pulmonary mucosa-associated lymphoid tissue lymphoma (MALToma) was diagnosed in seven subjects (33%).

CONCLUSIONS

Amyloid-associated cystic lung disease can occur with or without underlying CVD. Cystic lesions in the lung are commonly numerous, often are peribronchovascular or subpleural, and are frequently associated with nodular lesions that are often calcified. MALToma was a relatively frequent association.

Primary systemic amyloidosis: A rare cause for pleural effusion

Pleural effusion is a common problem dealt by most of the practicing clinicians. Some causes for pleural effusion are less often considered as a differential diagnosis owing to its rarity. Here we report a case of renal amyloidosis on alternate day haemodialysis for about two months time presenting with left sided pleural effusion. On evaluation this turned out to be a case of amyloidosis on thoracoscopic pleural biopsy suggesting the possibility of Primary systemic amyloidosis.

Clinical characteristics of amyloidosis with isolated respiratory system involvement: A review of 13 cases

BACKGROUND:

Isolated pulmonary amyloidosis is a very rare disease.

METHODS:

We retrospectively reviewed the records of patients with pathologically proven isolated pulmonary amyloidosis treated at our hospital from 1990 to 2011.

RESULTS:

There were 9 males and 4 females with a mean age of 54.7 years (range, 45–72 years) and the mean course of disease was 46.5 months (range, 5 months–15 years). The most common symptoms were cough (10/13), expectoration (8/13), hemoptysis (4/13), chest tightness (12/13), dyspnea (10/13), chest pain (3/13), fever (5/13), and body weight loss (2/13). Radiological findings included tracheal stenosis (2/13), bronchial stenosis with atelectasis (5/13), pulmonary nodules (3/13), lung consolidation (1/13), and lymph node enlargement with pleural effusion (2/13). Treatments included endotracheal stenting, endoscopic resection of tracheal and bronchial lesions, lung resection, and drug therapy with glucocorticoids, antineoplastic agents, or antibiotics. Four patients died of the disease within 1 year of diagnosis, 2 died of pneumonia at 3–4 years after original treatment, and the remaining patients are alive with follow-up ranging from 3 to 15 years.

CONCLUSIONS:

Isolated pulmonary amyloidosis is a rare disease with a relatively high mortality and its various manifestations make diagnosis challenging. Surgical resection of lesions and chemotherapy tend to be effective treatments.