INCIDENTAL PRESENTATION OF NODULAR PULMONARY AMYLOIDOSIS AS A SOLITARY MASS IN A FORMER SMOKER

Abstract

SESSION TITLE: Pulmonary Manifestations of Systemic Diesase SESSION TYPE: Fellow Case Report Posters PRESENTED ON: 10/09/2018 01:15 PM - 02:15 PM INTRODUCTION: An FDG avid mass in a smoker does not always mean malignancy and we describe one such case. CASE PRESENTATION: 65 year old male former 15 pack year smoker presented with a new right lower lobe mass incidentally discovered in the work up of hematuria. The patient was asymptomatic and denied chest pain, dyspnea or fevers. Blood pressure was 177/88 mm Hg and physical examination was otherwise unremarkable. A CT abdomen & pelvis demonstrated a 3 x 1.7 cm right para-spinal pleural based right lower lobe mass with calcifications. Pulmonary function testing was normal. A dedicated CT Chest confirmed calcifications in the mass and revealed no additional lung lesions [Fig. 1-A]. Given concern for malignancy, a PET/CT scan was performed. The mass was mildly FDG avid (SUV 3.0) [Fig. 1-B] while previously identified left hilar lymph nodes were not. The patient underwent a right video-assisted thoracic surgery wedge resection with mediastinal lymph node dissection. Frozen section revealed an eosinophilic lesion [Fig. 2-A] not concerning for carcinoma that later stained positive for Congo Red (‘apple-green’ birefringence under polarized light) confirming amyloidosis [Fig. 2-B]. There was no morphologic or immunophenotypic evidence of lymphoma or clonality. All lymph nodes examined were benign and a diagnosis of nodular pulmonary amyloidosis was made. Levels of serum free light chains were normal as was serum protein electrophoresis and immunophenotyping. DISCUSSION: Amyloidosis has an incidence of 6–10 cases per million person-years in the US [1]. The mean age is 67 years and male:female ratio is 3:2. The hallmark is extracellular deposition of misfolded protein fibrils leading to organ dysfunction and death. The disease can be hereditary or acquired and the process systemic or localized. Of the various types of amyloid proteins AL (amyloid light-chain) affects the lungs most often. Pulmonary amyloidosis is usually of 3 varieties – tracheobronchial, nodular parenchymal or diffuse alveolar septal. Lymphatic, laryngeal and pleural involvement have been described [2]. Nodular parenchymal amyloidosis may present with single or multiple nodules. These lesions are often localized, detected incidentally or via mass effect and frequently subpleural and located in the lower lobes. The differential diagnosis is large and includes malignancy and granulomatous lung diseases. If cysts are present, then Langerhans cell histiocytosis, lymphoid interstitial pneumonia and lymphangioleiomyomatosis may be considered. The gold standard of diagnosis is histological confirmation of amyloid via apple-green birefringence under polarized light. MALT lymphoma and multiple myeloma are reported associations with nodular pulmonary amyloidosis. Conservative management with excision of the amyloidomas usually suffice and prognosis is excellent. CONCLUSIONS: Pulmonary amyloidosis is rare but remains in the differential of lung masses. Reference #1: The lung in amyloidosis. Milani P et al. European Respiratory Review. 2017 Sep 6;26(145). Reference #2: Respiratory Tract Amyloidosis. State-of-the-Art Review with a Focus on Pulmonary Involvement. Rocha de Almeida et al. Lung. 2015 193:875-883. DISCLOSURES: No relevant relationships by Priyanka Makkar, source=Web Response No relevant relationships by Vishisht Mehta, source=Web Response No relevant relationships by Jean Santamauro, source=Admin input