see also:

• dermatology

• mottled skin (also known as livedo reticularis) is generally pale cool skin with a reticular pattern of venous congestion, usually of all limbs - not just hands and feet as with Raynaud's phenomenon

• exposure to cold leading to arteriolar vasospasm, especially common in young women.
• sometimes called cutis marmorata, typically resolves on warming and is harmless

• embolism, thrombosis, and cardiac conditions causing impaired circulation can manifest as livedo reticularis
• Severe form of this may result in phlegmasia caerula dolens or phlegmasia alba dolens
  • life threatening thrombosis of ileo-femoral / pelvic veins +/- IVC
• consider urgent CT venogram

• antiphospholipid syndrome (APS)
• vasculitis (e.g., polyarteritis nodosa, microscopic polyangiitis)
• rheumatoid arthritis
• systemic lupus erythematosus (SLE)

• medications and susbtances
  • amantadine, ergotamine, cocaine, and thiouracil

• infections:
  • hepatitis C virus
  • COVID-19 coronavirus (2019-nCoV / SARS-CoV-2)
• lymphoma
• hypothyroidism
• Cushing's disease
• other endocrine conditions