Abstract
INTRODUCTION: Penetrating foot injuries often involve retained foreign bodies (FBs), Although deep retained FBs are well recognized, superficial metallic FBs embedded specifically within the stratum corneum and mimicking plantar fasciitis are rarely reported and can be easily misdiagnosed. CASE PRESENTATION: A 55-year-old male physician experienced 2 weeks of left plantar pain during activity, self-diagnosed as plantar fasciitis，never had a medical check-up at the hospital. Due to the patient's own professional sensitivity as a doctor，a 1 mm black spot was noted on examination by himself，he decided to use a needle to prick this spot. A 2 mm stainless steel fragment was removed from the this black spot of stratum corneum, with immediate pain resolution. CLINICAL DISCUSSION: Superficial FBs embedded in thick plantar stratum corneum may avoid detection while causing weight-bearing significant weight-bearing pain due to dermal compression. This case highlights FB retention as a critical differential diagnosis for plantar pain, particularly post-trauma. The initial misdiagnosis occurred due to symptom similarity and the patient's prior experience; it underscores the importance of meticulous history and physical examination focusing on potential entry points or subtle skin changes, even if there is no significant history of foreign body punctures. It emphasizes the importance of a meticulous medical history and meticulous physical examination, and timely visits to a clinical specialist for chronic plantar pain. CONCLUSION: Plantar FB retention, including within the superficial stratum corneum, should be considered early in the differential diagnosis of unexplained foot pain, especially after potential penetrating injury. Thorough physical examination and history are paramount for diagnosis. This case highlights the importance of considering superficial retained foreign bodies in patients presenting with chronic plantar pain.