Cutaneous Polyarteritis Nodosa: Symptoms, Diagnosis, and Treatment

Cutaneous polyarteritis nodosa (cutaneous PAN or cPAN) is a rare type of vasculitis that affects medium-sized arteries in the skin and tissue just beneath it. It can cause tender lumps, a net-like reddish-purple pattern, and sometimes painful sores or areas of skin damage, most often on the legs. A skin-limited form usually follows a chronic pattern of flares and quieter periods, but clinicians need to check for signs that blood vessels in other organs are involved.

The word “cutaneous” means that the diagnosed disease is confined mainly to the skin. This is different from systemic polyarteritis nodosa, which can affect arteries supplying the kidneys, nerves, digestive tract, heart, and other organs. The skin findings can look similar in both forms, so a thorough assessment matters. A deep skin biopsy can help confirm the diagnosis, while blood, urine, and other tests help look for associated conditions or organ involvement.

Key points: painful nodules or livedo on the lower legs need medical evaluation; a biopsy must reach the deeper skin vessels to be useful; the skin-limited form and systemic PAN are treated differently; and there is no single treatment plan that fits everyone. Sudden nerve weakness, severe abdominal pain, blood in urine or stool, chest pain, or rapidly worsening skin injury needs urgent care.

What is cutaneous polyarteritis nodosa?

Polyarteritis nodosa is a form of vasculitis, a group of disorders involving inflammation of blood vessels. In PAN, inflammation affects small- to medium-sized muscular arteries and can narrow or injure them. When the affected vessels are in the skin and nearby tissue, the condition is called cutaneous PAN or cutaneous arteritis. Blood flow through inflamed vessels may be reduced, leading to pain, discoloration, and, in some cases, skin breakdown.

Cutaneous PAN is uncommon and may begin in childhood, adolescence, or adulthood. It often affects the lower legs and feet, particularly around pressure points, but lesions can also appear on the thighs, arms, trunk, buttocks, or other areas. The course can be episodic: new nodules or patches appear, some lesions improve, and flares can return months or years later.

The name can cause confusion because “PAN” is used for both cutaneous and systemic disease. Skin lesions alone cannot always separate them. A person may have fever, fatigue, muscle aches, joint pain, or nerve symptoms with cPAN, but these symptoms also mean clinicians should look carefully for systemic involvement and alternative explanations. A label of skin-limited disease is made after that assessment, not solely from seeing a rash.

Some cases have been reported after infections, including group A streptococcal infections and certain viral infections. This does not mean every infection causes cPAN or that an infection is present now. Autoimmune and autoinflammatory processes may contribute, and in many patients no single cause is identified. Rarely, a condition called deficiency of adenosine deaminase 2 (DADA2) can cause a PAN-like illness, especially when disease begins early in life or occurs with repeated strokes or immune problems.

Skin symptoms and other possible signs

The most recognizable skin findings are tender nodules beneath the skin, especially on the lower legs and thighs. The lumps may follow the path of an affected artery and can be felt before they are obvious on the surface. Skin over them may look red, purple, or brown. Larger inflamed plaques may have nodules around the edges and may leave darker patches as they fade.

Livedo reticularis is a net-like or lace-like pattern of reddish, violet, or bluish discoloration. In vasculitis, the pattern may be irregular or persistent rather than a harmless temporary change from cold. Purpura, which is purple-red spots that do not blanch when pressed, can occur. If blood flow is severely disrupted, patches of skin may become very dark, form blood-filled blisters, blister, or break into ulcers. Ulcers can be painful and may heal slowly or leave scars.

Some people experience general symptoms such as low energy, fever, sore throat, muscle aches, or joint pain. Nerve involvement may cause tingling, numbness, altered sensation, weakness, or reduced reflexes. These symptoms should be reported rather than attributed automatically to skin disease. A new foot drop, sudden weakness, rapidly spreading numbness, or other abrupt neurological change requires emergency evaluation.

Not every person has all of these findings. The skin may show only a few nodules or a mottled pattern, and other diseases can cause the same signs. A rash that is painless, itchy, or located elsewhere may still need examination if it is persistent or unusual. Do not try to diagnose vasculitis from photos or use leftover prescription medicines on the lesions.

When to get medical care

Arrange prompt medical evaluation for tender new nodules, persistent livedo, purpura, painful skin sores, or recurring ulcers, especially when accompanied by fever, muscle aches, numbness, or weakness. The clinician may need to coordinate dermatology with rheumatology or another specialty. If a person already has cPAN, new symptoms outside the skin should be reported promptly because they may change the assessment.

Seek emergency care for sudden weakness or numbness on one side, facial droop, trouble speaking, severe new headache, chest pain, difficulty breathing, fainting, severe abdominal pain, vomiting blood, black or bloody stool, or blood in the urine. These symptoms can indicate serious blood-vessel, nerve, heart, or digestive involvement and should not wait for a routine appointment.

Rapidly darkening or black skin, a growing ulcer, severe pain, pus, spreading warmth or redness, or fever with a wound also warrants urgent assessment. A secondary infection or loss of blood flow may need prompt treatment. People who are taking immune-suppressing medicines should contact their care team early if they develop a fever or signs of infection.

How is cutaneous PAN diagnosed?

There is no single blood test that diagnoses cPAN. A clinician reviews the skin changes, when they began, how they fluctuate, recent infections, medicines, family history, age at onset, and any nerve, muscle, joint, kidney, digestive, or heart symptoms. The examination may include checking blood pressure, pulses, sensation, strength, and skin lesions in different stages.

A deep skin biopsy is often needed to confirm the diagnosis. The medium-sized arteries involved in cPAN lie deeper than the tiny superficial vessels sampled by a shallow punch. A dermatologist or surgeon may take an incisional or deep punch sample from an active tender nodule or another representative lesion, including tissue beneath the dermis. The right site and depth matter; the clinician explains the scar and wound-care risks before the procedure.

Under the microscope, the pathologist looks for inflammation and damage in the wall of a medium-sized artery. The changes may include fibrinoid necrosis, inflammatory cells, and partial narrowing or blockage. Because vessel involvement can be patchy and lesions change over time, a sample from an old scar may be less helpful than one from an active area. Sometimes additional tissue or testing is needed if the first biopsy is not conclusive.

Blood and urine tests do not prove cPAN, but can help find an infection, check inflammation, assess kidney function, and look for signs of another condition or systemic PAN. Clinicians may order tests for hepatitis or other infections based on the history, and they may check for symptoms suggesting organ involvement. Blood pressure and urine are useful parts of assessing kidney-related concerns. The exact work-up depends on the person rather than a fixed test panel.

When symptoms suggest systemic PAN, additional testing may include imaging of blood vessels or evaluation of an affected nerve, muscle, or organ. The American College of Rheumatology and Vasculitis Foundation guideline addresses systemic PAN and explicitly excludes cutaneous PAN because the forms are managed differently. That distinction helps prevent a treatment recommendation for one form from being applied automatically to another.

Cutaneous PAN versus systemic PAN

In skin-limited cPAN, inflammation is primarily confined to arteries in the skin and tissue beneath it. Some people have general symptoms or nerve-related symptoms, so “skin-limited” does not mean the condition is trivial or symptom-free. The diagnosis also does not guarantee that a patient will never develop a new issue. Follow-up helps clinicians reassess if symptoms change.

Systemic PAN affects medium-sized arteries supplying internal organs. Possible signs include severe abdominal pain, blood in the stool, new high blood pressure, kidney problems, chest symptoms, testicular pain, nerve weakness, or organ-specific pain. These signs do not prove PAN, but they need prompt investigation. Systemic PAN can become life-threatening and requires urgent specialist treatment.

Both forms may involve skin nodules, livedo, purpura, or ulcers, which is why skin appearance alone cannot distinguish them. Clinicians combine the biopsy with symptoms, examination, blood pressure, urine tests, kidney function, and other targeted investigations. If disease began in childhood or there are repeated strokes, immune deficiency, or a strong family pattern, a specialist may consider rare inherited conditions such as DADA2.

Treatment options

Treatment depends on whether disease is limited to the skin, how painful or damaging the lesions are, whether ulcers are present, and whether an associated infection or other condition is found. The evidence for cPAN treatment is limited. A systematic review found seven case series with 325 adults and no controlled comparison group, so it could not determine one best treatment for all patients. The care team balances symptom control against the possible harms of long-term immune-suppressing medicine.

Symptom and wound care

For less severe disease, clinicians may focus on pain relief, protecting inflamed areas from repeated pressure or injury, and caring for blisters or ulcers. A wound-care professional can recommend suitable dressings and help monitor healing. Keep wounds clean according to clinician instructions, avoid harsh chemicals or unprescribed topical medicines, and do not cut or drain a nodule at home.

Anti-inflammatory pain medicines or other pain treatments may be considered if appropriate for the person's health. Some medicines can affect kidney function, increase bleeding, or interact with other prescriptions, so “over the counter” does not mean risk-free. Ask the clinician or pharmacist before taking new pain medicine, especially if there are kidney, stomach, blood pressure, bleeding, or pregnancy concerns.

Medicines for active or recurring disease

When symptoms are more active, recurrent, painful, or causing ulcers, a specialist may recommend a short course of an oral corticosteroid or another prescription treatment. Colchicine, dapsone, hydroxychloroquine, or an immune-modifying medicine may be considered in selected cases. The choice depends on disease severity, age, other health conditions, test results, prior treatment response, and likely side effects. These treatments require medical supervision and sometimes laboratory monitoring.

Because immune-suppressing medicines can increase infection risk and affect blood counts, liver, kidneys, or other systems, clinicians weigh the expected benefit against harms and arrange follow-up. Do not use leftover prednisone or someone else’s medicine. If you already take a steroid or immune-modifying medicine, follow the prescribed taper or schedule and contact the prescriber before any change.

If a specific infection is found or repeatedly linked to flares, the clinician may treat that infection and consider whether preventing recurrence is appropriate. Antibiotics are not a general treatment for vasculitis and should not be taken without a clinician's recommendation. In DADA2, treatment may be different and involve a specialist approach such as a tumor necrosis factor inhibitor; genetic or functional testing is considered when the clinical picture supports it.

Monitoring and follow-up

Follow-up may include checking whether nodules or ulcers have healed, whether new lesions have appeared, whether pain is improving, and whether new symptoms suggest internal organ involvement. If a medicine is prescribed, follow-up may also include blood tests, infection prevention, review of side effects, and a plan for how long the treatment is expected to continue. Contact the care team if symptoms return while tapering or after treatment ends.

Outlook and day-to-day care

Cutaneous PAN often has a chronic course with periods of worsening and remission. Some flares settle spontaneously or after treatment; ulcers and discoloration can take longer to heal. New flares may happen months or years later. The skin-limited form generally has a more favorable outlook than systemic PAN, but persistent pain, ulceration, and nerve symptoms can still affect daily life.

There is no routine home test to tell whether a flare is active or whether disease has spread. Keep follow-up appointments and let the clinician know about new symptoms even if the rash appears unchanged. Photos taken in similar light and notes about pain, walking, fever, numbness, and wound healing can help describe the course accurately.

Ask for help managing wound dressings, footwear, school or work accommodations, and activity during flares. Gentle protection from repeated pressure may reduce irritation at affected sites, but avoid strict activity restrictions unless recommended. Emotional support can also help with a long-lasting condition and uncertainty about recurrence. If pain or sleep is not controlled, tell the care team; it is a treatable part of the burden.

Questions to ask your care team

• Does the biopsy need to be deep enough to reach medium-sized arteries?
• What findings support skin-limited cPAN, and what tests are being used to check for systemic disease?
• Could an infection, medicine, or another condition be contributing?
• What wound-care or pain plan is suitable for the current lesions?
• What are the likely benefits and risks of each medicine being considered?
• Which symptoms should prompt same-day care or an emergency visit?
• How often should I be reassessed, especially if new symptoms appear?

Bring a current medicine list and mention recent infections, travel, new supplements, and symptoms such as tingling or abdominal pain. If the condition started in childhood or a young person has livedo with repeated strokes, immune problems, or unexplained fevers, mention this clearly so the specialist can decide whether a rare genetic condition should be considered.

Frequently asked questions

Sources and further reading

• DermNet: Cutaneous polyarteritis nodosa
• DermNet: Polyarteritis nodosa pathology
• Systematic review of treatment options for cutaneous polyarteritis nodosa
• Vasculitis Foundation: Polyarteritis nodosa
• American College of Rheumatology and Vasculitis Foundation guideline for systemic PAN
• 2024 retrospective study of clinical and treatment outcomes in cutaneous PAN
• NIH Genetic and Rare Diseases Information Center: Cutaneous polyarteritis nodosa

Medical information notice: This article is for education and is not a diagnosis or treatment plan. Cutaneous and systemic PAN can look alike but require different evaluation and care. Seek a qualified clinician for persistent painful nodules, livedo, purpura, ulcers, nerve symptoms, or any possible organ-related symptoms. Emergency symptoms should be assessed immediately.