Clinical, laboratory and genetic features of Erdheim-Chester disease patients: analysis of a retrospective cohort of two reference centers in Latin America.

Objectives and Methods: Erdheim-Chester disease (ECD) is a rare histiocytic neoplasm with a heterogeneous clinical course, ranging from localized and asymptomatic bone lesions to a multisystem disease, causing significant morbidity and mortality. There are few cohorts published, mainly from North America and Europe. We retrospectively collected clinical data on sixteen biopsy-proven ECD patients diagnosed and treated at two Brazilian reference centres for histiocytic disorders from January 2006 to February 2020.Results: Median time from onset of symptoms to diagnosis was 13 months (0.1-142). The main organ involved in ECD was bone (75%) and also 75% of the patients presented involvement of more than one organ, characterizing a multi-organic form. BRAF status was available in 81.2% of patients and BRAF V600E mutation was detected by Sanger sequencing in only 18.8%, which can be explained by the low sensitivity of this technique. All patients were treated due to symptomatic disease and a median of two lines (range: 1-7) of therapy were needed. The most common first-line therapy used was α-interferon (75%). The median progression-free survival was 7.5 months, and the median OS was not reached.Discussion and Conclusion: In the largest Latin American cohort of patients with ECD reported to date, we observed findings which resemble demographic characteristics, sites of involvement and treatment choices reported by other groups. The outcomes may be better with target therapies such as BRAF and MEK inhibitors in patients with mutation and with the adoption of recently published consensus recommendations for the management of ECD patients.

Erdheim-Chester disease: atypical presentation of a rare disease.

We report the clinical case of an adult patient referred to our hospital because of trismus due to a tumour in the right infratemporal and pterygomaxillary fossa. He referred hyporexia, weight loss and right trigeminal neuralgia. On physical examination, he had trismus and diplopia. On neuroimaging, the tumour invaded the central nervous system affecting the right temporal lobe and orbit, and the sellar region. Tumour biopsy revealed foamy histiocytes and isolated giant multinuclear cells immunoreactive to CD68 and negative to CD1a and S100. A diagnosis of Erdheim-Chester disease was made. Non-evidence of large bone involvement was found in neither plain radiographs nor Technetium 99 m bone scintigraphy. BRAFV600E mutation analysis was negative. Because of raised intracranial pressure, a debulking surgery of the intracranial histiocytic process was performed. The patient improved his symptoms and remains clinically stable after 12 months of treatment with pegylated interferon-α-2a 180 µg/weekly.