Differential Diagnosis for Darkening Skin on Hands and Feet with Antibiotic

• Single most likely diagnosis
  • Minocycline-induced hyperpigmentation: This condition is a well-documented side effect of long-term minocycline use, characterized by blue-gray discoloration of the skin, particularly on the hands and feet.
• Other Likely diagnoses
  • Fixed drug eruption: A common adverse reaction to medications, including antibiotics, which can cause skin darkening or hyperpigmentation, especially on the hands and feet.
  • Tetracycline-induced phototoxicity: Certain antibiotics, such as tetracyclines, can increase the risk of phototoxicity, leading to skin darkening or hyperpigmentation, particularly in sun-exposed areas like the hands and feet.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Sepsis or disseminated infection: In rare cases, darkening skin on the hands and feet can be a sign of a severe, life-threatening infection, such as sepsis or disseminated fungal infection, which requires prompt medical attention.
  • Vasculitis: Certain types of vasculitis, such as polyarteritis nodosa or cryoglobulinemia, can cause skin discoloration, including darkening of the skin on the hands and feet, and can be life-threatening if left untreated.
• Rare diagnoses
  • Argria (silver poisoning): Although rare, exposure to silver or silver-containing products can cause a bluish-gray discoloration of the skin, known as argyria, which can affect the hands and feet.
  • Hemochromatosis: A genetic disorder characterized by iron overload, which can cause skin hyperpigmentation, including darkening of the skin on the hands and feet, although this is a less common presentation.