WHY MISDIAGNOSIS PERSISTS
At least 3 reasons account for the persistent misdiagnosis of unexplained lesions as spider bites by many patients and some health care professionals:
• Arachnophobia is a common fear. It is easy, and perhaps oddly comforting, to ascribe unexplained and potentially frightening symptoms to spider bites. In the United States, the spider most commonly implicated as the cause of dermonecrotic lesions is the brown recluse (Box).10-13
• Patients often have difficulty in accepting that a medical problem has an endogenous origin. They prefer to blame an external agent, such as a poison or envenomation.
• Some health care professionals may find it easier to rely on the diagnosis of "spider bite" than to generate an adequate differential diagnosis for a skin lesion of unknown origin.
Although spider bites can produce dermonecrotic wounds, the differential diagnosis of such lesions is extensive; it includes microbial infections, dermatologic disorders, vasculitides, and environmental exposures (Table).14-16