Trans-Epidermal Elimination Due to Insulin Formulation: Report of a Rare Adverse Effect

A 45-year-old female with type-2 diabetes experienced trans-epidermal elimination (TEE) of insulin formulation, presenting as itchy lesions at injection sites. The condition was linked to a change in her isophane insulin brand, leading to a foreign body granulomatous reaction. Histopathology confirmed TEE, and treatment involved switching to oral diabetes medications, resolving the lesions. This case highlights the need to consider rare causes of perforating dermatoses beyond common ones, as insulin and its excipients can induce such reactions.