Also known as chilblains.
- Caused by exposure to cold
- Red to purple macules, papules or nodules on acral skin or the thighs or buttocks
- Superficial and deep perivascular lymphocytic infiltrate
- Marked edema of the papillary dermis
- Edema of blood vessel with transmural lymphocytic infiltrates
- Occasional fibrin thrombi in the capillaries of the dermal papillae
- The epidermis is usually unremarkable, but epidermal necrosis or ulceration may sometimes be seen.