Sean Klepper M.D.
Stephen Lyle, M.D., ...
- The majority of arthropod bites are clinically insignificant. Serious reactions can result, however, from the bites of the black widow and brown recluse spiders.
- The reaction to the bite can range from a minor erythematous papule to a large nodule with ulceration and/or vesicle formation.
- Wedge-shaped mixed dermal inflammatory infiltrate composed of lymphocytes, histiocytes eosinophils and sometimes neutrophils
- Dermal edema
- Excoriated lesions may have ulceration and/or a scale crust.
- Arthropod mouth parts may be seen in the center of the lesion.
- Spider bites often show extensive necrosis and suppurative inflammation, sometimes extending into the subcutaneous fat and soft tissues, and vasculitis may be present.