DermDx: Rash on Arms, Knees, and Back


  • Figure 1. Rash on back

  • Figure 2. Rash on knees and thigh.

  • Figure 3. Histologic slide of eruptive xanthoma showing lipid deposits (black arrows).

A 53-year-old man presents to the office with a rash on his arms, knees, and back. The rash was sudden in onset and has persisted for a month. He denies any associated pruritus, bleeding, or recent illness. His medical history is significant for type 2 diabetes, hypertension, hypercholesterolemia, and herniation of T6 and T7 spinal discs. His family history is significant for familial hypertriglyceridemia. Upon questioning the patient admits to having persistently high triglycerides despite taking both fenofibrate 145 mg and extended-release niacin 500 mg twice daily; which resulted acute pancreatitis. On physical examination, the patient has small 2 to 4 mm, dome-shaped, discreet, yellow-pink papules scattered on his trunk and grouped on bilateral extensor extremities.

Eruptive xanthomas are a benign form of xanthoma found most often on extensor surfaces as papular lesions.1-5 These localized lipid deposits form as a result of dyslipidemia where there is lipid uptake by macrophages in the dermis.1,2,4,5 Clinical presentation involves...

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Eruptive xanthomas are a benign form of xanthoma found most often on extensor surfaces as papular lesions.1-5 These localized lipid deposits form as a result of dyslipidemia where there is lipid uptake by macrophages in the dermis.1,2,4,5 Clinical presentation involves multiple clusters of dome-shaped, yellow or skin-colored erythematous, nonfollicular papules, nodules, or plaques on the extremities and buttocks.1-5 Koebner phenomenon — where lesions arise in sites of skin trauma — may be observed.1,2,4 These papules may be asymptomatic or present with pruritus, tenderness, and pain.

In addition to the lesions, eruptive xanthomas may also present with gastrointestinal or ophthalmic symptoms such as abdominal pain secondary to hyperlipidemia and lipemia retinalis.2 As a manifestation of hypertriglyceridemia, these dermatoses can also be a sign of other systemic diseases. For example, eruptive xanthomas are often found in patients with uncontrolled diabetes mellitus,1,4,5 hypertriglyceridemia-induced pancreatitis,6 or genetic deficits such as that of lipoprotein lipase.2,4

Other conditions should be ruled out in the differential diagnosis including disseminated granuloma annulare (GA), juvenile xanthogranuloma, and generalized eruptive histiocytoma.1,3 Granuloma annulare is characterized by small, yellow-red or skin-colored nodules or papules in a ring formation.1 The disseminated version of GA is associated with diabetes mellitus and hypertriglyceridemia similar to what is found in eruptive xanthoma. Eruptive xanthoma is differentiated from GA by the presence of lipid deposits, xanthomized histiocytes, and hyaluronic acid deposition. Non-Langerhans cell histiocytoses are characterized by reddish-brown or yellow papules and includes juvenile xanthogranuloma. This disease is most common in younger populations and is often a solitary presentation of yellow-orange lesions on the scalp, face, and upper trunk.1 Generalized eruptive histiocytoma is another type of non-Langerhans cell histiocytosis but is very rare.7 It presents in crops of papules that are firm and red-brown, with symmetric distribution prone to flares and spontaneous resolution.1 Generalized eruptive histiocytoma can be differentiated from eruptive xanthomas because of a lack of Touton giant cells on histologic examination.7

Zehra Rizvi is a third year medical student at Nova Southeastern University College of Osteopathic Medicine in Fort Lauderdale, Florida. Katrina Hansen, DO, is the dermatology chief resident at Beaumont Hospital, Farmington Hills, Michigan. Annette C. La Casse, DO, is the program director for Beaumont Farmington Hills Dermatology Residency Program. John Pui, MD is the chief of pathology at Beaumont Hospital.


  1. Kashif M, Kumar H, Khaja M. An unusual presentation of eruptive xanthoma: a case report and literature review. Medicine (Baltimore). 2016;95(37):e4866. doi:10.1097/MD.0000000000004866
  2. Naik NS. Eruptive xanthomas. Dermatol Online J. 2001;7(2):11.
  3. Abdelghany M, Massoud S. Eruptive xanthoma. Cleve Clin J Med. 2015;82(4):209-10. doi:10.3949/ccjm.82a.14081
  4. Zaremba J, Zaczkiewicz A, Placek W. Eruptive xanthomas. Postepy Dermatol Alergol. 2013;30(6):399-402. doi:10.5114/pdia.2013.39439.
  5. Virath R, Mehta S, Balai M, Meena M, Gupta LK. Eruptive xanthoma and granuloma annulare in association with metabolic disorder. Indian J Dermatol. 2021;66(2):199-201. doi:10.4103/ijd.IJD_421_19
  6. Inoue-Nishimoto T, Hanafusa T, Hirohata A, et al. Eruptive xanthoma with acute pancreatitis in a patient with hypertriglyceridemia and diabetes. Ann Dermatol. 2016;28(1):136-7. doi:10.5021/ad.2016.28.1.136
  7. Cardoso F, Serafini NB, Reis BD, Nuñez MD, Nery JA, Lupi O. Generalized eruptive histiocytoma: a rare disease in an elderly patient. An Bras Dermatol. 2013;88(1):105-8. doi:10.1590/s0365-05962013000100015.
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