What causes vascular lines and petechiae in middle back?

Hi,

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I have observed the picture and also gone through the history of present and past illness (attachment removed to protect patient identity). I could observe that there is tendency for the lesions to assume a shape that is generally seen due to excoriation. This implies that the primary lesion or symptom induces the subject to scratch resulting in this picture.

Vasculitis tends to be diffuse and involves various body areas and more so on the dependent parts like lower legs and feet. Most such patients tend to spontaneously recover over time. However, an attempt must be made to find out whether any local factor might be operative like an insect or bug bite, postural pressure on the area, any disorder that would cause itching like heat rash or an allergy to some agent that is off and on applied to this part of the body. The petechiae seem to have resulted from scratching. Careful observation leads one to the cause in a good number of cases. For symptomatic relief, one can consider giving anti-allergic medications.