Erdheim-Chester disease: an unusual presentation of an uncommon disease

The Mayo Clinic Histiocytosis Working Group Consensus Statement for the Diagnosis and Evaluation of Adult Patients With Histiocytic Neoplasms: Erdheim-Chester Disease, Langerhans Cell Histiocytosis, and Rosai-Dorfman Disease

Histiocytic neoplasms, a rare and heterogeneous group of disorders, primarily include Erdheim-Chester disease, Langerhans cell histiocytosis, and Rosai-Dorfman disease. Due to their diverse clinical manifestations, the greatest challenge posed by these neoplasms is the establishment of a diagnosis, which often leads to a delay in institution of appropriate therapy. Recent insights into their genomic architecture demonstrating mitogen-activated protein kinase/extracellular signal-regulated kinase pathway mutations have now enabled potential treatment with targeted therapies in most patients. This consensus statement represents a joint document from a multidisciplinary group of physicians at Mayo Clinic who specialize in the management of adult histiocytic neoplasms. It consists of evidence- and consensus-based recommendations on when to suspect these neoplasms and what tests to order for the diagnosis and initial evaluation. In addition, it also describes the histopathologic and individual organ manifestations of these neoplasms to help the clinicians in identifying their key features. With uniform guidelines that aid in identifying these neoplasms, we hope to improve the awareness that may lead to their timely and correct diagnosis.

Erdheim-Chester Disease Involving Lymph Nodes and Liver Clinically Mimicking Lymphoma: A Case Report

Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocytosis and multisystem disease. First described in 1930, there are no more than 750 cases reported. The etiology remains unknown, but a majority of cases of ECD and Langerhans cell histiocytosis were found to have clonal mutations involving genes of the mitogen-activated protein kinase pathway. We recently encountered a 53-year-old male patient with extensive ECD involving the systemic lymph nodes, pleura, liver, and long bones clinically mimicking malignant lymphoma. Biopsies were performed at multiple sites, including a pleural mass, an external iliac lymph node, bone marrow, and the liver. Based on histopathological and immunohistochemical findings of positivity for CD68 and negativity for CD1a and S-100, the patient was diagnosed with ECD. Interferon-α was administered as the first-line treatment, but the patient rapidly progressed to hepatic failure after 2 months of treatment. We report this rare case of ECD clinically mimicking malignant lymphoma and diagnosed by careful pathological review.