Rare findings in pulmonary amyloidosis

Clinical History

A case of a 55-year-old female patient is presented, who did not have a history of cigarette smoking nor professional exposure to chemicals, and did not complain of respiratory symptoms.
A chest X-ray, performed for a car accident, showed abnormal findings, so a chest CT was subsequently carried out.

Imaging Findings

Chest CT revealed some large nodular opacites with amorphous calcifications and multiple well-defined cystic lesions in both lungs, moreover, a subsegmental collapse of the middle lobe was detected (Fig. 1).
Tracheobronchial tree presented multifocal and irregular wall thickenings, some with calcifications (Fig. 2). Some lymph nodes in mediastinum were found with short axis up to 10 mm (Fig. 1). No pleural abnormalities were detected.
Bronchoscopy confirmed multifocal and irregular yellowish wall thickening in tracheobronchial tree. Mucosal biopsy was done at tracheal wall and Congo-red staining revealed amyloid deposit of greenish birefringence under polarized light microscopy.
Pulmonary function testing of the patient revealed mild obstructive syndrome and mild reduction in CO diffusing capacity. The findings were consistent with airways and lung amyloidosis.

Discussion

Amyloidosis is a rare disease characterized by extracellular deposition of various proteins in β–pleated sheets, disrupting organ function. Two forms of amyloidosis are commonly described, systemic and localized.
Systemic amyloidosis can be primary, with monoclonal immunoglobulins in serum or urine immunoelectrophoresis, can be secondary to several diseases (i.e. chronic infections, Crohn’s disease, Sjrogren syndrome, etc.) or it can be familial [1]. Localized amyloidosis is defined as amyloid deposition isolated to an organ or district without systemic deposition [1, 2].
Amyloid in the respiratory tract has been classified by authors at The Mayo Clinic as associated with systemic amyloidosis or localized pulmonary disease [3].
In systemic amyloidosis, thoracic involvement may commonly show diffuse interstitial or nodular lung disease, adenopathy and pleural disease. In localized amyloidosis, three types of respiratory injuries are described: tracheobronchial, nodular and interstitial involvement [3, 4, 5].
We underline some rare findings in our case, in particular the patient described herein presented nodular pulmonary amyloidosis in association with tracheobronchial involvement. In light of these data, we emphasize that tracheobronchial amyloidosis is exceptionally described associated with lung involvement [3, 4, 6]. To the best of our knowledge, to date, only few and sporadic cases are reported in English literature describing lung and tracheobronchial lesions in the same patient [3, 7].
Secondly, it is interesting to notice that localized pulmonary involvement in amyloidosis without systemic amyloidosis is very rare, more precisely the localized form occurs in approximately 10-20% of patients with amyloidosis [1, 2]. In our case, after detecting amyloid deposits on tracheobronchial tree, a diagnosis of localized form of amyloidosis was reached on the basis of an abdominal fat biopsy excluding systemic amyloid deposits.
Rarely mediastinal enlarged lymph nodes are present in localized pulmonary disease, while pleural effusions is well documented in patients with systemic amyloid disease often related to congestive heart disease or nephrotic syndome [3, 4]. We did not notice hilar/mediastinal adenopathy nor pleural abnormalities.
Finally, cystic lung disease (as in lymphoid interstitial pneumonia) or pulmonary nodular amyloidosis has been occasionally reported in association with Sjogren syndrome, together with the combination of pulmonary cysts and nodules [8, 9]. In this regard, our patient had a long history of sicca syndrome, positive Shirmer test, and SSA SSB positive autoantibodies, data consistent with Sjögren syndrome. On the basis of the clinical presentation, quite nonspecific, we recommended surveillance with periodic pulmonary function tests and chest radiographs.

Differential Diagnosis List

Final Diagnosis

Localized pulmonary amyloidosis

URL:	https://www.eurorad.org/case/11963
DOI:	10.1594/EURORAD/CASE.11963
ISSN:	1563-4086