Vasculitishttps://en.wikipedia.org/wiki/Vasculitis
Vasculitis is a group of disorders that destroy blood vessels by inflammation. Vasculitis can be classified by the cause, the location, the type of vessel or the size of vessel. Laboratory tests and skin biopsy may be required to find underlying causes. Treatments are generally directed toward stopping the inflammation and suppressing the immune system. Typically, corticosteroids such as prednisone are used.

○ Diagnosis
Vasculitis limited to the skin may improve over time. However, blood and urine tests may be done to detect systemic or autoimmune disorders.

○ Treatment ― OTC Drugs
If vasculitis is limited to the skin without invasion of other organs, a steroid ointment could be used.
#OTC steroid ointment
  • Other systemic disorders (autoimmune diseases) involving vasculitis should be ruled out.
  • This is a typical picture of vasculitis of the leg. A urine test can be done to check for abnormalities in kidney function.
  • Livedo vadculopathy
  • Purpura
  • Henoch schonlein purpura
References An aetiological & clinicopathological study on cutaneous vasculitis 22382191 
NIH
Of the 61 patients studied, hypersensitivity vasculitis (HSV) [23 (37.7%)] and Henoch Schonlein purpura (HSP) [16 (26.2%)] were the two most common forms. Systemic involvement was seen in 32 (52.45%) patients. Drugs were implicated in 12 (19.7%) cases, infections in 7 (11.4%) and connective tissue disorders in 4 (6.5%) cases. No association was seen between history of drug intake and tissue eosinophilia and also between histologically severe vasculitis and clinical severity.
 Leukocytoclastic Vasculitis 29489227 
NIH
Leukocytoclastic vasculitis is a cutaneous, small-vessel vasculitis of the dermal capillaries and venules. This condition can be idiopathic or can be associated with infections, neoplasms, autoimmune disorders, and drugs. Key clinical features of leukocytoclastic vasculitis include palpable purpura on the lower extremity, small vessel involvement, and, in about 30 percent of individuals, extracutaneous involvement. Most cases of idiopathic cutaneous, small vessel vasculitis are self-limited with 90 percent of cases resolving in weeks to months of onset. Otherwise, treatment depends on the severity of disease and can range from an oral corticosteroid taper to various steroid-sparing immunosuppressive agents.