A RARE CASE OF ERDHEIM-CHESTER DISEASE MASQUERADING AS METASTATIC LUNG CANCER

Abstract

SESSION TITLE: Lung Cancer 3 SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: 10/09/2018 01:15 PM - 02:15 PM INTRODUCTION: Erdheim-Chester Disease (ECD) is a non-Langerhans histiocytosis characterized by xanthomatous infiltration by CD68 positive, CD1a and S100 negative foamy histiocytes causing multi-system involvement. It was first identified in 1930, however, there have only been approximately 500 reported cases. Concomitant pituitary involvement, multiple axial skeletal lesions, and lung involvement is suggestive of ECD. Diagnosis typically involves histopathological studies in the appropriate clinical and radiological context. Here we present a case of ECD diagnosed during investigation of diabetes insipidus (DI) and a lung mass. CASE PRESENTATION: A 63-year-old female with a history of hyperlipidemia presented to the Endocrinology clinic for evaluation of polydipsia which was later diagnosed as DI. Extensive serum evaluation for etiology was unremarkable. MRI brain showed thickened infundibulum with increased enhancement suggestive of an inflammatory or infiltrative process. As part of her routine health maintenance, she had CTA coronaries done which showed a 2.1 cm spiculated left lung mass. Further investigations with repeat chest CT, PET scan and a bone scan confirmed malignant appearing left lung lesion along with body-wide skeletal lesions involving bilateral femurs, tibias, and left humerus, concerning for metastatic lung cancer. She underwent biopsy of the lung mass followed by lobectomy. Pathology findings were consistent with adenocarcinoma of the lung with immunostaining positive for TTF-1 and napsin-A. Subsequently, the patient underwent open biopsy of the left humeral lesion, which showed extensive fibrosis, focal lymphoplasmacytic infiltration, and scattered histiocytes. Immunostaining was negative for S100 and CD1a and positive for CD68. Pituitary involvement, DI, the presence of multiple skeletal lesions and staining profile is highly suggestive of ECD. Peripheral blood cytometry was positive for BRAF-V600 mutation. We are awaiting tissue studies for mutational analysis prior to treatment initiation. DISCUSSION: Patients with ECD are usually males of age 40-70 years; our patient had atypical features with female gender and late age of onset. DI associated with pituitary stalk thickening represents the most common neurological symptom, along with long bone involvement. Given the rarity of the disease, there are no clear guidelines regarding treatment approach; consensus guidelines recommend a treatment tailored for organ predominance and clinical severity to help facilitate treatment of “high risk” groups. CONCLUSIONS: Currently, the 5-year survival is less than 70%. However, the discovery of activating mutations of BRAF in 54% of the ECD patients has led to a modified therapeutic approach. A recent study suggests Vemurafenib (BRAF inhibitor) has prolonged efficacy in patients with BRAF V-600 mutant ECD and warrants consideration as the new standard of care for these patients. Reference #1: Cives, M., Simone, V., et.al. (2015). Erdheim–Chester disease: A systematic review. Retrieved March 03, 2018, from https://doi.org/10.1016/j.critrevonc.2015.02.004 Reference #2: Diamond, E. L., Subbiah, V., et.al. (2017). Vemurafenib for BRAF V600-Mutant Erdheim-Chester Disease and Langerhans Cell Histiocytosis: Analysis of Data From the Histology-Independent, Phase 2, Open-label VE-BASKET Study. Retrieved March 03, 2018, from https://www.ncbi.nlm.nih.gov/pubmed/29188284 DISCLOSURES: No relevant relationships by Nayla Ahmed, source=Web Response No relevant relationships by Ayushi Chauhan, source=Web Response No relevant relationships by Prashant Grover, source=Web Response No relevant relationships by Joerg Rathmann, source=Web Response No relevant relationships by Parin Shah, source=Web Response No relevant relationships by Aniket Sharma, source=Web Response No relevant relationships by John Thayer, source=Web Response