Systemic Necrotizing Arteritis
Systemic necrotizing arteritis (SNA) is a group of severe and complex systemic vasculitides marked by necrotizing, transmural (full-thickness) inflammation of small and medium-sized arteries. Unlike cutaneous necrotizing venulitis, which affects only small veins in the superficial dermis, SNA strikes deeper, in the subcutis and fascia where the main feeding arteries run. The result is aneurysm formation, narrowing and clotting of the vessels, and widespread ischemic necrosis of the skin and vital organs (kidneys, heart, peripheral nerves, gut). Typical members of this group include polyarteritis nodosa (PAN), microscopic polyangiitis (MPA) and other ANCA-associated vasculitides. At Haute-Derma, we provide urgent clinical diagnosis, coordinate systemic immune treatment and offer a plan to preserve and rebuild deeply necrotic skin.
How the disease damages the skin, and the immune processes involved:
- Transmural Inflammation of Medium-Sized Arteries:
- Immune complex deposition or activation of anti-neutrophil cytoplasmic antibodies (ANCA) sets off acute inflammation in the walls of arteries in the subcutis.
- Neutrophils flood through every layer of the vessel wall (intima, media and adventitia) and release protein-digesting enzymes (elastase, collagenase) that destroy the internal elastic lamina.
- Fibrinoid Necrosis, Thrombosis and Aneurysm Formation:
- The intense inflammation causes fibrinoid necrosis of the whole vessel wall. As smooth muscle and elastic fibers weaken, the wall bulges into small aneurysms (microaneurysms) that may be felt on examination.
- Damage to the endothelium triggers the clotting cascade, forming clots that can completely block the artery.
- Deep Subcutaneous Necrosis and Large Skin Defects:
- Blockage of the feeding arteries in the subcutis cuts off the blood supply to the dermis and epidermis above.
- The resulting acute ischemia causes full-thickness skin necrosis, with painful nodules under the skin, black patches of dry gangrene and deep ulcers that can reach the muscle fascia.
Skin Findings in Systemic Necrotizing Arteritis (SNA)
| Clinical Sign | What It Looks Like | Cellular and Molecular Mechanism |
|---|---|---|
| Painful Subcutaneous Nodules | Firm, easily felt nodules deep in the subcutis or fat, lying along the course of arteries in the lower leg; very tender to pressure. | Necrotizing transmural inflammation of a segment of a medium-sized subcutaneous artery, causing aneurysm and swelling of the surrounding tissue. |
| Livedo Racemosa | A broken, irregular, wavy red-purple net on the lower legs, thighs and buttocks that does not blanch with pressure. | Partial blockage of subcutaneous arteries slows blood flow in the superficial venous network. |
| Necrotic Blisters and Deep Ulcers | Hemorrhagic blisters break open into deep, very painful ulcers with steep edges and a black necrotic base (eschar). | Complete blockage of the feeding artery causes ischemic necrosis through the full thickness of the epidermis and dermis. |
| Digital Gangrene | Fingertips and toes turn blue and cold, then dry and black, with numbness or stabbing pain. | Blockage of end arteries in the digits by clots forming on vessel walls with fibrinoid necrosis. |
| Associated Systemic Features | High fever, weight loss, peripheral nerve pain (mononeuritis multiplex), high blood pressure, kidney failure, acute abdominal pain. | Necrotizing arteritis occurring at the same time in the kidneys, nerves, gut and heart. |
Systemic Necrotizing Arteritis (SNA) vs. Cutaneous Necrotizing Venulitis (CNV)
| Feature | Systemic Necrotizing Arteritis (SNA / PAN) | Cutaneous Necrotizing Venulitis (CNV / LCV) |
|---|---|---|
| Vessels affected | Small and medium-sized arteries in the subcutis/fat | Postcapillary venules in the superficial dermis |
| Main skin lesions | Deep nodules, livedo racemosa, deep undermined ulcers, digital gangrene | Palpable purpura, superficial hemorrhagic blisters |
| Pain | Very severe; neuropathic or ischemic pain | Moderate burning or stinging |
| Internal organ involvement | Very common and severe (kidneys, nerves, gut, heart) | Usually rare or mild (except IgA vasculitis) |
| ANCA and serology | ANCA (p-ANCA/c-ANCA) or hepatitis B/C often positive | Usually ANCA-negative; C3/C4 complement may be low |
Our Approach
At Haute-Derma, evaluating a patient with suspected systemic necrotizing arteritis calls for precision and urgent action:
- Clinical and Systemic History Assessment:
- We look for deep nodules under the skin, broken patches of livedo racemosa and necrotic ulcers with a black slough.
- We ask about warning signs of organ damage: nerve pain (numbness or weakness in the legs), bloody stools, unexplained weight loss, blood in the urine or a sudden rise in blood pressure.
- Deep Skin and Subcutaneous Biopsy:
- A deep punch biopsy (or an elliptical incisional biopsy) taking the full thickness of skin down to the deep fascia. This is essential because the affected arteries lie in the subcutis.
- Histology: transmural arteritis, fibrinoid necrosis, neutrophil infiltration and no superficial venulitis.
- Whole-Body Laboratory and Imaging Screening:
- Complete blood count, markedly raised inflammatory markers (ESR/CRP), kidney function and urinalysis.
- Serology: p-ANCA, c-ANCA, hepatitis B (HBsAg, particularly linked to PAN) and hepatitis C.
- Digital subtraction angiography (DSA) or CT angiography to detect microaneurysms in the kidneys and mesentery.
Treatment Options at Haute-Derma
Because the necrosis can be severe, our plan at Haute-Derma closely combines systemic immune therapy with skin-preserving care:
- Coordinated Systemic Immunosuppression (Essential):
- Patients must be jointly assessed and actively treated with immunology or nephrology/rheumatology specialists: high-dose corticosteroids (intravenous methylprednisolone or oral prednisolone) combined with potent immunosuppressants such as cyclophosphamide, rituximab or azathioprine.
- If the patient has hepatitis B (HBV-related PAN), antiviral therapy (entecavir or tenofovir) is combined with plasma exchange.
- Managing Deep Necrotic Ulcers and Pain at Haute-Derma:
- Conservative debridement: Black necrotic tissue (eschar) is removed gradually using enzymatic or gentle ultrasonic debridement, avoiding aggressive cutting that could cause arterial bleeding.
- Biocompatible dressings: Hydrocolloid or alginate dressings, or negative pressure wound therapy (NPWT), to stimulate granulation tissue from the base of deep ulcers.
- Restoring Microcirculation and Rebuilding the Skin Surface:
- Photobiomodulation: Red (630 nm) and near-infrared (830 nm) LED light to improve blood flow around the wound, ease burning nerve pain and speed healing.
- Post-inflammatory scar treatment: Once the ulcer has filled with granulation tissue and closed, treatments such as 1064 nm laser toning and microneedle RF are used to soften fibrotic scar tissue and restore the skin surface.
