A cutaneous manifestation of a systemic disease

Case history

An African American man aged 52 years reported the development of new bumps on his knees and elbows over the previous two to three weeks. The patient had not seen a doctor for six months but had a history of diabetes that was treated with diet alone. Aside from some increased thirst and more frequent urination over the previous two months, he said he was otherwise feeling well.

The patient was 6'1" in height and weighed 214 lb. He was normotensive. Darkly pigmented, firm and non-tender papules were evident on his knees and elbows (figures 1 and 2). There was no pruritus associated with these papules.

Questions

What is your diagnosis and how would you proceed with work up and treatment of this patient?

Discussion

Eruptive xanthomas are a cutaneous manifestation of a chronic systemic disease. Eruptive xanthomas can be seen in and secondary causes of hyperlipidaemia; examples include familial dyslipoproteinaemia, familial hypertriglyceridemia, and familial lipoprotein lipase deficiency.¹ Diabetes out of control is a common cause of hyperlipidaemia and is certainly a contributing factor in this case. Although the patient may also have a genetic abnormality of his lipoproteins, further classification will not change the treatment of his diabetes and hyperlipidaemia. Regardless of the underlying metabolic defect, his family members should be screened for hyperlipidaemia and diabetes.

Eruptive xanthomas are typically seen as papules on the elbows, knees, buttocks, and back. In light-skinned people the papules are red and may have a yellow centre. Papules may become confluent and if larger than 5 mm would be classified as nodules. In this darkly pigmented patient the papules appear hyperpigmented.

Treatment and case resolution The most pressing treatment priority is the patient's diabetes that is out of control. The patient was started on a prescribed regimen of metformin with additional diet and exercise counselling. Gemfibrozil was prescribed to decrease the high concentrations of triglyceride and cholesterol. Fortunately, treatment of the eruptive xanthomas involves nothing more than treating the underlying hyperlipidaemia.²

Because this hyperlipidaemia occurs at least in part secondary to the diabetes, diabetic control will promote resolution of the eruptive xanthomas.

As the patient's diabetes and hyperlipidaemia came under better control, the eruptive xanthomas began to disappear. The papules resolved more quickly than the hyperpigmentation.

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