Cold panniculitis.

Cold panniculitis has been described in children and young women following cold exposure. Histopathologically, cold panniculitis shows a mostly lobular panniculitis, which consists of an infiltrate of lymphocytes and histiocytes in the fat lobules. Usually, the dermis shows a superficial and deep perivascular infiltrate mostly composed of lymphocytes, with no vasculitis. Inflammation is most intense at the dermal-subcutaneous junction. Differential diagnosis of cold panniculitis should be established with subcutaneous fat necrosis of the newborn, sclerema neonatorum, poststeroid panniculitis, chilblains, and frostbites.