Rare Cutaneous Manifestations of Erdheim Chester Disease: A Case Report and Literature Review

Erdheim Chester disease (ECD) is a rare and complex non-Langerhans histiocytic systemic disease that affects multiple organ systems, including the bones, heart, lungs, and central nervous system. Fewer than 1,000 cases have been reported in the medical literature and dermatological manifestations of the disease are rare but can provide valuable diagnostic clues for this challenging disease. The cutaneous manifestations of ECD can take many forms, including nodules, plaques, papules, and xanthomas. These lesions can occur on any part of the body and may be solitary or multiple. Cutaneous manifestations of ECD have been reported to occur in up to 20% of cases, but the true prevalence may be higher, as many cases may go undiagnosed. We present the case of a 62-year-old gentleman with a history of ECD currently on vemurafenib who presented with multiple painless subcutaneous nodules on his back after an excision biopsy under local anesthetic revealed histological features of ECD. The objective of this case report is to raise awareness of ECD and its dermatological manifestations. Further research is warranted to better understand the pathogenesis and morphology of cutaneous involvement in ECD.

Erdheim Chester Disease - Unusual Presentation with Isolated Skeletal Lytic Lesions

Introduction

Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocytosis (LCH) of unknown origin that was first described in 1930. Since then, almost 600 cases have been reported worldwide. Even though this disease primarily affects the bone, it has a varied clinical spectrum of presentation ranging from asymptomatic bone lesions to multisystem involvement. Owing to its protean manifestations ECD is often misdiagnosed or diagnosed late.

Case Report

We present a 48-year-old female with a long long-standing history of recurrent bone lesion of the tibia and multiple trivial trauma fractures of long bones. Recently, she also developed a persistent headache and painful swelling of the right shoulder and left hip joint. Radiographs revealed multiple lytic and lytic sclerotic lesions. With the probable diagnosis of LCH, she underwent biopsy which revealed features characteristic of ECD.

Conclusion

This case highlights the fact that histopathological confirmation is the key to distinguish various types of histiocytic neoplasms. Overlapping clinical and radiological features with atypical manifestations can occur in both LCH and ECD and does not rule out either of them.

JAK2 V617F mutation in plasma cell-free DNA preceding clinically overt myelofibrosis: Implications for early diagnosis

A 52 year-old man with Erdheim-Chester Disease (ECD) (a non-Langerhans polyostotic sclerosing histiocytosis) had next-generation sequencing (NGS) performed as part of his diagnostic workup. In addition to the tissue BRAF V600E mutation that is found in over 50% of ECD cases, he was also found to have a JAK2 V617F alteration in cell-free circulating tumor DNA (ctDNA) (liquid biopsy). The latter was thought to be an "incidental" finding, perhaps due to clonal hematopoiesis (though this usually occurs in older individuals), as his blood counts were normal and he had no splenomegaly. Approximately 13 months after the ctDNA test showing JAK2 V617F, he developed anemia, thrombocytopenia, and splenomegaly. Marrow biopsy then showed megakaryocytic atypia and markedly increased marrow fibrosis, consistent with WHO grade 2 of 3 myelofibrosis. Therefore, the patient was determined to have ECD with a typical BRAF V600E mutation, as well as primary myelofibrosis, with the latter diagnosis manifesting clinically over one year after the JAK2 V617F was first detected in ctDNA. He recently was started on the JAK2 inhibitor ruxolitinib. This case demonstrates that genomic alterations detected by liquid biopsy for evaluation of specific malignancies already present may serve as an early harbinger of hematological disease.