A Near Missed Diagnosis of Pulmonary Adenocarcinoma and How Immunohistochemistry for Amyloid Typing Can Lead Us Astray

Abstract

SESSION TITLE: Cancer Case Report Posters ISESSION TYPE: Case Report PosterPRESENTED ON: Sunday, March 23, 2014 at 01:15 PM - 02:15 PMINTRODUCTION: Pulmonary amyloidosis has rarely been described in conjunction with primary pulmonary malignancy. Here we describe the case of a 74-year-old male with amyloidosis in whom a diagnosis of lung cancer was nearly missed. CASE PRESENTATION: A 74-year-old man, non-smoker with unremarkable family history, presented for a second opinion after being diagnosed with pulmonary amyloidosis. CT chest revealed a right upper lobe 3.2 x 2.3 cm mass, a right lower lobe 2.7 x 2 cm nodule, and a bilateral micronodular infiltrate. The transbronchial biopsy specimen stained positive for Congo red. Immunohistochemistry (IHC) was positive for lambda light chain and transthyretin/pre-albumin (ATTR). Mass spectrometry (MS) revealed ATTR amyloidosis without light chain deposition. Protein electrophoresis revealed monoclonal IgG lambda. Bone marrow biopsy revealed a B-cell lymphoproliferative disorder. Cardiac echocardiogram and magnetic resonance imaging were consistent with amyloidosis. Blood MS was negative for mutant TTR, reducing the differential to age-related wild-type (WT)-ATTR (formerly known as senile systemic) versus immunoglobulin (Ig) light-chain (AL) amyloidosis. Due to confusion over amyloid subtype, decision was made to biopsy the larger right upper lobe mass. Pathology revealed invasive papillary adenocarcinoma. A right upper lobectomy was performed, and the biopsy specimen again showed strong reactivity of lambda light chain and ATTR by IHC. The patient was ultimately correctly diagnosed with pulmonary adenocarcinoma and systemic WT-ATTR amyloidosis by MS. The monoclonal gammopathy was correctly recognized as being secondary to his age-related lymphoproliferative disorder. DISCUSSION: To our knowledge, this is the first case to describe pulmonary adenocarcinoma in conjunction with age-related WT-ATTR amyloidosis. It has previously been reported with AL amyloidosis only. ATTR amyloidosis can be misdiagnosed as AL amyloidosis by IHC1,2. This has important implications, as chemotherapy and/or stem cell transplantation is indicated in systemic AL but not WT-ATTR amyloidosis. In addition, WT-ATTR amyloidosis carries a better prognosis, with average survival of 75 versus 11 months3. CONCLUSIONS: IHC has low sensitivity and specificity for amyloid typing and can lead to misdiagnoses and incorrect treatment, suggesting MS may be the only acceptable methodology for this purpose.Reference #1: Comenzo RL et al. Seeking confidence in the diagnosis of systemic AL (Ig light-chain) amyloidosis: patients can have both monoclonal gammopathies and hereditary amyloid proteins. Blood. 2006;107(9):3489-3491.Reference #2: Lachmann HJ et al. Misdiagnosis of hereditary amyloidosis as AL (primary) amyloidosis. N Engl J Med. 2002;346(23):1786-1791.Reference #3: Ng et al. Senile systemic amyloidosis presenting with heart failure: a comparison with light chain-associated amyloidosis. Arch Intern Med. 2005 Jun 27;165(12):1425-9. DISCLOSURE: The following authors have nothing to disclose: Mary Klecka, Fabien Maldonado, Angela Dispenzieri, Nelson LeungNo Product/Research Disclosure Information.