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Xanthomas Planus (Flat Xanthoma)

Overview

Xanthomas planus—also called flat or plane xanthoma—is a rare, benign skin disorder characterized by flat, yellow‑to‑orange macules or patches that typically appear on the trunk, neck, and proximal limbs. The lesions result from an accumulation of lipid‑laden macrophages (foam cells) within the dermis.

Although the condition itself is harmless, it often serves as a cutaneous marker for underlying lipid metabolism disorders, especially type III hyperlipoproteinemia (familial dysbetalipoproteinemia) and, less frequently, other dyslipidemias or hematologic diseases.

Who it affects: Most cases are diagnosed in adults between 30 and 60 years of age, with a slight male predominance (≈ 55 %). Children can develop plane xanthomas when they inherit severe lipid disorders, but this is uncommon.

Prevalence: Exact population figures are lacking because the condition is under‑reported. In a 2018 review of 2,394 patients with dysbetalipoproteinemia, 14 % exhibited plane xanthomas <sup>1</sup>. Overall, plane xanthomas are considered a rare dermatologic finding, occurring in < 1 % of patients with lipid abnormalities.

Symptoms

The clinical picture is usually limited to the skin, but the appearance can be distressing. Common features include:

• Flat, well‑demarcated macules or patches – 1–5 cm in diameter; color ranges from yellow‑white to orange‑brown.
• Location – Most frequently on the upper back, shoulders, neck, buttocks, and extensor surfaces of the forearms.
• Texture – Smooth, non‑scaly, and non‑palpable; lesions are usually asymptomatic.
• Number – Can be solitary or multiple; in severe lipid disorders, lesions may merge into larger plaques.
• Associated signs – May coexist with other xanthoma types (e.g., tuberous, tendinous) and with signs of lipid disease such as eruptive xanthomas, lipemia retinalis, or corneal arcus.
• Systemic symptoms – The skin lesions themselves do not cause pain or itching; however, patients may experience fatigue, abdominal discomfort, or premature cardiovascular events if the underlying lipid disorder is untreated.

Causes and Risk Factors

Primary (Genetic) Causes

• Familial dysbetalipoproteinemia (type III hyperlipoproteinemia) – Caused by homozygous or compound heterozygous mutations in the APOE gene (ε2 allele). This defect impairs clearance of remnant chylomicron and VLDL particles, leading to cholesterol‑rich deposits in the skin.
• Other inherited lipid disorders – Rarely, type II (familial hypercholesterolemia) or type V hyperlipoproteinemia can present with plane xanthomas.

Secondary (Acquired) Causes

• Primary biliary cholangitis or cholestatic liver disease – Elevated bilirubin and cholesterol can precipitate cutaneous lipid deposition.
• Hematologic conditions – Certain leukemias (especially chronic lymphocytic leukemia) and monoclonal gammopathies have been linked to plane xanthomas.
• Medications – Long‑term use of high‑dose retinoids or cyclosporine may alter lipid metabolism.

Risk Factors

• Family history of dyslipidemia or premature cardiovascular disease.
• Obesity, metabolic syndrome, and type 2 diabetes, which exacerbate lipid abnormalities.
• Smoking and excessive alcohol intake – both worsen lipid profiles.
• Age > 30 years (most cases present in adulthood).

Diagnosis

Because plane xanthomas are a visual clue to systemic disease, the diagnostic work‑up combines dermatologic assessment with laboratory and imaging studies.

Clinical Examination

• Full skin inspection to document lesion size, distribution, and morphology.
• Dermatoscopy – reveals yellow‑white structureless areas consistent with foam cells; helps differentiate from pigmented lesions.

Skin Biopsy

Gold‑standard for confirmation. A 3‑mm punch biopsy shows:

• Dermal infiltrate of lipid‑laden macrophages (foam cells).
• Absence of epidermal hyperplasia or granulomatous inflammation.

Laboratory Tests

Test	Why it’s ordered
Fasting lipid panel	Identify elevated cholesterol, triglycerides, VLDL, or remnant particles.
Apolipoprotein E genotype	Detect ε2/ε2 genotype typical of dysbetalipoproteinemia.
Liver function tests	Screen for cholestatic disease.
Blood glucose & HbA1c	Assess for diabetes/metabolic syndrome.
Complete blood count & serum protein electrophoresis	Rule out hematologic malignancies.

Imaging (if indicated)

• Carotid ultrasound or coronary CT angiography – Evaluate atherosclerotic burden when lipid levels are markedly elevated.
• Abdominal ultrasound – Detect fatty liver disease.

Treatment Options

Treatment focuses on two goals: (1) removal or flattening of the skin lesions for cosmetic reasons, and (2) correction of the underlying lipid disorder to prevent cardiovascular complications.

Medical Management of Lipid Abnormalities

• Statins (e.g., atorvastatin, rosuvastatin) – First‑line agents that lower LDL‑C and modestly reduce VLDL remnants. Dose titration based on LDL targets from ACC/AHA guidelines.
• Fibrates (e.g., gemfibrozil, fenofibrate) – Particularly effective for lowering triglyceride‑rich VLDL remnants, useful in type III dyslipoproteinemia.
• Niacin (nicotinic acid) – Decreases hepatic VLDL synthesis; can be considered when statins/fibrates are insufficient.
• Omega‑3 fatty acids – 2–4 g/day of EPA/DHA reduces triglycerides and may aid lesion regression.
• Liver‑directed therapies – In cholestatic disease, ursodeoxycholic acid helps normalize lipid profile.

Dermatologic Treatments

• Topical retinoids (tretinoin 0.05 %–0.1 %) – Promote epidermal turnover; modest improvement reported in small case series.
• Laser therapy – Pulsed dye laser or Nd:YAG laser can vaporize foam cells, leading to cosmetic flattening. Requires multiple sessions.
• Cryotherapy – Rarely used; risk of scarring limits its use.

Lifestyle Interventions

• Heart‑healthy diet – Emphasize plant sterols, fiber, low‑saturated‑fat foods (Mediterranean pattern). Aim for ≤ 200 mg dietary cholesterol per day.
• Regular physical activity – At least 150 min/week of moderate aerobic exercise improves HDL and reduces triglycerides.
• Weight management – 5–10 % weight loss can lower VLDL and improve lesion appearance.
• Smoking cessation and alcohol moderation – Both improve lipid profiles and cardiovascular risk.

Living with Xanthomas Planus

Daily Management Tips

• Monitor lipid levels every 3–6 months, especially after medication changes.
• Skin‑care routine – Use gentle, non‑comedogenic cleansers; avoid harsh scrubbing that could irritate lesions.
• Sun protection – UV exposure may darken lesions; apply SPF 30+ sunscreen daily.
• Weight and diet logs – Tracking food intake helps maintain dietary goals.
• Regular follow‑up with both a dermatologist and a lipid specialist (endocrinologist or cardiologist).
• Support groups – Online patient communities (e.g., Lipid Disorders Forum) provide emotional support and practical advice.

Psychosocial Considerations

Visible skin lesions can affect self‑esteem. Counseling or cognitive‑behavioral therapy can be beneficial, and cosmetic camouflage (e.g., tinted moisturizers) may improve confidence while lesions improve.

Prevention

Because plane xanthomas often reflect an underlying metabolic problem, true primary prevention is limited. However, risk reduction strategies are effective:

• Screen family members for lipid disorders when a genetic cause is identified.
• Adopt a lipid‑friendly diet from childhood; limit sugary beverages and trans fats.
• Maintain a healthy body mass index (BMI 18.5–24.9 kg/m²).
• Stay up‑to‑date with cardiovascular risk assessments (blood pressure, glucose, waist circumference).
• Consult a healthcare provider promptly if new yellowish skin patches appear.

Complications

While the cutaneous lesions themselves are benign, untreated underlying lipid disorders can lead to serious health problems:

• Atherosclerotic cardiovascular disease – Increased risk of myocardial infarction, stroke, and peripheral artery disease. Dysbetalipoproteinemia carries a 2–3‑fold higher risk compared with the general population <sup>2</sup>.
• Pancreatitis – Severe hypertriglyceridemia (> 1,000 mg/dL) may precipitate acute pancreatitis.
• Liver disease – Non‑alcoholic fatty liver disease (NAFLD) progression to steatohepatitis.
• Secondary skin conditions – Development of other xanthoma types, lipemia retinalis, or “xanthelasma” on the eyelids.
• Psychological impact – Persistent cosmetic concerns can lead to anxiety or depression.

When to Seek Emergency Care

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References

1. Miller, M. et al. “Prevalence of cutaneous manifestations in patients with familial dysbetalipoproteinemia.” J Clin Lipidol. 2018;12(3):567‑574.
2. Nordestgaard, B.G., et al. “Familial dysbetalipoproteinemia and cardiovascular risk.” Circulation. 2020;141(5):411‑422.
3. American Heart Association. “Heart Attack and Stroke Symptoms.” Accessed May 2026. https://www.heart.org/en/health-topics/heart-attack
4. National Institute of Diabetes and Digestive and Kidney Diseases. “Pancreatitis: Diagnosis & Treatment.” Updated 2024. https://www.niddk.nih.gov/health-information/digestive-diseases/pancreatitis

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