Macular Lymphocytic Arteritis (MLA)

Lymphocytic arteritis; Lymphocytic thrombophilic arteritis; Lymphocytic T-cell vasculitis; Hyaline arteriosclerosis with lymphocytic infiltration.

MLA is a rare, chronic, cutaneous, small- to medium-vessel arteritis characterized by asymptomatic, hyperpigmented, reticulated macules or plaques on the lower extremities. Histopathology reveals lymphocytic arterial infiltration and hyaline wall thickening without fibrinoid necrosis or systemic vasculitic involvement. It is considered a benign vasculitis confined to the skin.

Extremely rare. Most commonly affects middle-aged women (peak incidence: 40–60 years). Only case reports and small case series exist. Likely underdiagnosed due to subtle clinical features.

Belongs to the group of cutaneous small- and medium-vessel vasculitides. Considered a distinct entity from cutaneous polyarteritis nodosa (cPAN) due to its benign clinical course and lymphocytic rather than neutrophilic infiltrates.

Unknown. A chronic immune-mediated process with T-cell-dominated infiltration is suspected. Possible associations with coagulation abnormalities, autoimmunity (e.g., ANA positivity, SS-A/B), or neoplasia have been reported but are not consistent.

• Non-painful, reddish-brown to violaceous macules or slightly raised plaques
• Typically in a reticulated or linear configuration resembling livedo
• Primarily localized on the lower extremities, especially the shins
• No ulceration or systemic symptoms
• Chronic, stable course over months to years

• Clinical: asymptomatic macular hyperpigmentation of the legs
• Biopsy (deep punch into subcutis required):
  • Lymphocytic infiltration of dermal or subcutaneous arteries
  • Hyaline thickening of vessel walls
  • Absence of fibrinoid necrosis, neutrophilic infiltrates, or leukocytoclasia
• Immunohistochemistry: CD3+ T-cell predominance; no immune complex deposition
• Laboratory tests: usually normal (no elevation of CRP/ESR, ANA may be positive but nonspecific)

Primarily affects the distal lower legs; less commonly the thighs, arms, or trunk.

Gradual development of discoloration or faint pigmentation on the legs, usually discovered incidentally. No systemic complaints, pain, or itching.

Medium-sized arteries with concentric hyaline wall thickening and perivascular lymphocytic infiltration. No neutrophils, fibrin deposition, or necrosis. Sometimes intraluminal thrombi. Epidermis typically spared.

• Cosmetic disfigurement
• No known progression to systemic vasculitis
• No ulceration, necrosis, or internal organ damage reported

Benign and chronic. Lesions are persistent but stable. No progression to systemic vasculitis observed.

No known primary prevention. Early recognition through histopathology is key in atypical livedo-like pigmentation.

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