Epidemiology and geographic clustering of Erdheim-Chester disease in Italy and France.

This geoepidemiological study, performed in Italy and France, shows that Erdheim-Chester disease is increasingly diagnosed and cases cluster in specific geographic areas, namely southern Italy and central France. Disease frequency inversely correlates with the Human Development Index.

Erdheim-Chester disease: description of two illustrative cases involving the lung.

AIM: Erdheim-Chester disease represents a clonal systemic proliferation of histiocytes. Bone is the most common site of involvement, although almost any organ, including the lungs, can be affected. METHODS AND RESULTS: The diagnosis of Erdheim-Chester disease can be difficult, owing to its rarity and protean presentation. Correlation between clinical, radiological and histological findings is mandatory for identification of the disease. Foamy histiocytes, lacking Langerhans cell markers, represent the typical histological findings, although their absence does not rule out Erdheim-Chester disease. Identification of BRAF mutation can be helpful in making the diagnosis, and allows for the development and application of targeted therapies in this setting. CONCLUSIONS: Herein, we describe two cases presenting with lung involvement and vertebral lesions, lacking the more typical long-bone involvement. One case histologically mimicked Rosai-Dorfman disease. However, both cases harboured the pathognomonic BRAFV600E mutation.

Secondary biopsy of non-oncogenic-driven lung cancer may reveal a clinically sensible histologic change. A brief report of two paradigmatic cases.

After an initial benefit, non-small-cell lung cancer (NSCLC) patients receiving therapy with tyrosine kinase inhibitors develop drug resistance through a variety of mechanisms. Among these, tumor histology changes are a mechanism of acquired resistance in epidermal growth factor receptor-mutated and anaplastic lymphoma kinase-rearranged NSCLC cases. The current availability of therapeutic approaches to overcome tyrosine kinase inhibitor resistance in oncogenic-driven lung cancers justifies secondary tumor biopsy in these patients. On the other hand, little is known about the mechanism of disease progression in non-oncogenic driven NSCLC. Nevertheless, NSCLC lacking "druggable" genetic alterations are not considered for secondary biopsy, as it is commonly believed that these tumors cannot develop histologic or molecular changes. Herein, we report two paradigmatic cases of wild-type NSCLC showing histologic "change" on secondary biopsy, allowing for a successful switch in therapeutic strategy.

Does Immunohistochemistry Represent a Robust Alternative Technique in Determining Drugable Predictive Gene Alterations in Non-Small Cell Lung Cancer?

Immunohistochemistry (IHC) is a widely-tested, low-cost and rapid ancillary technique available in all laboratories of pathology. This method is generally used for diagnostic purposes, but several studies have investigated the sensitivity and specificity of different immunohistochemical antibodies as a surrogate test in the determination of predictive biomarkers in non-small cell lung cancer (NSCLC), particularly for Epidermal Growth Factor Receptor (EGFR) gene mutations, Anaplastic Lymphoma Kinase (ALK) gene and ROS1 rearrangements. In this review, a critical examination of the works comparing the consistency of IHC expression and conventional molecular techniques to identify genetic alterations with predictive value in NSCLC is discussed. Summarizing, data on sensitivity and specificity of antibodies against ALK and ROS1 are very consistent and time has come to trust in IHC at least as a cost-effective screening tool to identify patients with rearranged tumors in clinical practice. On the other hand, mutant-specific antibodies against EGFR demonstrate a good specificity but a lowto- fair sensitivity, raising some cautions on their employment as robust predictive biomarkers. A brief comment on preliminary experiences with antibodies against BRAF, RET, HER2 and c-MET is also included.