CASE REPORT

A 42 year old man presented to the rheumatology department with a two year history of arthralgia of the knees and ankles. Past medical history included myocardial infarctions at the ages of 33 and 40, with coronary artery bypass grafting at age 39. His father had died of myocardial infarction aged 54. The patient was noted to have xanthomata. Examination of his joints was normal. Laboratory tests, including erythrocyte sedimentation rate, red and white blood cell count, glucose, renal, and liver function tests, were normal. Serum cholesterol was raised at 7.8 mmol/l. Radiographs showed no abnormality of the joints, but demonstrated sclerosis of the distal femora and proximal tibia. Computed tomography (fig 1) and magnetic resonance imaging confirmed sclerosis without osteolysis. Biopsy of the left tibia showed sheets of large foamy histiocytes infiltrating the marrow, confirming the diagnosis of Erdheim-Chester disease. One year later, over a few weeks, he developed a painful swelling in the right mid-thigh associated with low grade fever and weight loss. Repeat blood cultures were negative and no material was aspirated. Radiographs showed a more aggressive appearance with erosion of the cortex, and possible malignant change. A second bone biopsy was performed under general anaesthetic. In the early postoperative period he died of bronchopneumonia and respiratory failure.

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Figure 1

Computed tomography scan showing bilateral osteosclerosis of the femora.

At post mortem longitudinal sections of the right femur showed a yellow haemorrhagic infiltrate filling the medullary cavity and eroding the cortex. Histological changes were thickened trabeculae and marrow spaces filled with a mixed inflammatory infiltrate, in which there were numerous lipid laden macrophages. There was erosion of the cortex and the infiltrate extended into the adjacent soft tissues. An oil red O stain for lipid was positive, and there was no malignant change. There were foamy macrophages within the lungs and within the enlarged neck lymph nodes.

DISCUSSION

Since the first cases of Erdheim-Chester disease were reported in 1930,² an increasing clinical spectrum has emerged.³ However, to our knowledge this patient is the first with lymph node involvement. The pseudo-malignant phase has not previously been reported, although a discharging sinus in the thigh has been observed.⁴ Premature atherosclerosis was the third unusual feature, and lipid laden histiocytes characterise this disease.⁵ The family history suggests that this patient had coincidental familial hypercholesterolaemia, although raised fasting lipids have been found previously in patients with this disease,^3,6 and there is a report of premature death from renal and cardiovascular failure.⁷ There is no established treatment for this rare disease, and death from respiratory failure, as in this case, is a recognised outcome.⁸