Erdheim chester disease: A trio of intriguing cases

Abstract

Histiocytoses are a group of heterogeneous diseases that comprise Langerhans cell histocytosis (LCH) and non-LCH. Erdheim Chester disease (ECD) is a non-LCH, clonal systemic proliferation of histiocytes resulting in lesions that can manifest in virtually any tissue within the body. Diagnosis is based on the combined clinical features, histology and characteristic radiological findings. We present three cases. These cases include a 63-year-old woman investigated for bony abnormalities discovered on staging investigations following a diagnosis of breast cancer, a 71-year-old male presenting with diminishing renal function and left ureteric obstruction and a 67-year-old man with fatal multi-systemic ECD involvement, including retroperitoneal fibrosis, dilated cardiomyopathy and bone pain that was diagnosed late in its course. BRAFV600E mutational analysis was performed and a mutation was detected in each of the three cases. Recent research into such cases has described an association between LCH and ECD and it is suggested that BRAFV600E has an important role in the emergence of both diseases. Like LCH, the majority of ECD patients harbour acquired activating mutations in the MAPK/ERK pathway genes with BRAFV600E and NRAS mutations the most prevalent. These findings open the gateway to the possibility of targeted therapeutic treatment for those with significant clinical disease.