Category: Calcium/Bone Disorders
Objective : Erdheim-Chester disease (ECD) is a rare clinical entity with only approximately 500 cases described in medical literature since first described in 1930. It is considered underdiagnosed and there has been an increase in reports recently as physicians are beginning to have a higher clinical suspicion for it.
Methods : We describe one case at our institution
Results : A 55 year-old engineer presented to endocrine clinic with hypogonadism and bony abnormalities. Eight years prior he had noted bony pain in his lower extremities. A whole-body bone scan demonstrated symmetric uptake in the lower extremities and skull. He was told he had osteopetrosis and that no further work up was needed. Contemporaneously, he developed fatigue, decreased strength, and low libido. Total testosterone was found to be less than 50 and also had hypothyroidism. He was started on testosterone and levothyroxine with symptom improvement. Two years prior to our evaluation he developed acute visual defects. MRI demonstrated osteopetrosis of the skull and bilateral orbital masses with intracranial extension with bilateral cavernous sinus infiltration and suprasellar extension with encasement of the pituitary infundibulum. Biopsy was consistent with orbital pseudotumor for which he was started on prednisone and methotrexate. Subsequent imaging demonstrated worsening sellar extension. He was referred to endocrine clinic. Given presence of pituitary and bone abnormalities, a sphenoid biopsy was performed. Pathology revealed a xanthomatous histiocytic lesion consistent with Erdheim-Chester and molecular testing was positive for a BRAF V600 mutation. The patient was then started on vemurafenib.
Discussion : ECD is a rare non-Langerhans histiocytic process seen mainly in men during their fifth decade. Bilateral osteosclerotic involvement, typically of the long bones of the lower extremity, is almost universally described. Multiorgan extra-skeletal infiltration occurs frequently with cardiovascular involvement being most common. However, neurological, pituitary and bilateral orbital involvement are also frequently seen with diabetes insipidus described as the most common endocrine disorder and the third most common symptom, which this patient lacked. Diagnosis is made by histologic biopsy that demonstrate CD68+ histiocytes that stain negative for CD1 to decipher it from Langerhans histiocytosis. Treatment is with interferon alpha unless found to have BRAF V600 mutation in which case vemurafenib is the preferred agent.
Conclusion : ECD is a rare entity that should be considered in patients presenting with both pituitary and bone abnormalities. Targeted therapy against BRAF V600 is a potential treatment option for some patients.
University of Colorado
My name is Abtin Farahmand and I am a current fellow at the University of Colorado. I am a southern California native and did my undergraduate at UCLA. After my time at UCLA, I pursued medical school at Albert Einstein College of Medicine. After medical school, I went back to UCLA for internal medicine training at which time I grew an interest in Endocrinology doing research on endocrinopathies associated with new cancer agents. I accepted a fellowship at the University of Colorado in Endocrinology where I am now currently. I enjoy going on hikes with my wife Alison, and our little but ambitious pup, Ophelia. When we aren't hiking, we like to stay active in the city whether it is jogging, biking, or hitting the gym!
University of Colorado
Dr. Saxon joined the faculty at the University of Colorado School of Medicine in August 2017. He graduated from Washington University in St. Louis with a BA in Anthropology, received his MD from Loyola University Stritch School of Medicine, and did his residency training at the University of Michigan. He completed fellowship in Endocrinology, Metabolism, and Diabetes at the University of Colorado in 2015 and then completed a VA Advanced Health Services Research fellowship during which time he also earned a MS in Clinical Sciences degree. His current research is focused on variability in utilization of anti-obesity medications within the VA and other large healthcare organizations. Clinically he practices as a general endocrinologist and has strong interests in diabetes, weight management, thyroid disorders, and osteoporosis.