Cold panniculitis is a dermatological condition that involves a sudden-onset nodular rash, developing in regions of the body that have been subject to a cold temperature, due to inflammation of adipose tissue.
Cold panniculitis (CP) is a disorder that can affect both adults and children. It is caused by exposure of various regions of the body to a cold temperature and, subsequently, there is a wide range of areas on which it may appear.
Patients may present with indurated nodules in areas of the body exposed to cold. The nodules have ill-defined margins and appear approximately 1 to 3 days following the exposure. The erythematous lesions are expected to develop to painful and firm nodules over the days . Pediatric patients tend to exhibit them on the forehead and cheeks and rarely on the extremities such as the toes, with the lesions assuming a lilac/red color   . This is attributed to these two areas of the body being more constantly exposed to a cold temperature during the winter and less protected . Cold panniculitis does not lead to systemic involvement and, therefore, constitutional symptoms are not reported. Except for the characteristic dermatological manifestations, a medical history of fever is the sole complaint that may accompany a case of CP.
The induration gradually subsides and the disorder is a self-limiting one, eventually resolving in approximately two weeks . Ulceration of the nodules or plaque formation and crusting thereof may also be observed .
Several sub-categories of CP have been reported in the literature. Equestrian cold panniculitis is a type of CP that involves nodular lesions appearing in young women who engage in horse-riding . Cold is also the culprit behind these cases and the lesions are typically observed on the upper lateral part of the thigh, with bilateral involvement being a possibility. Popsicle panniculitis is a type of cold panniculitis that occurs following sucking on an ice cube or popsicle, with lesions appearing on the cheeks. Lastly, a case has been reported, concerning CP-induced by a cold therapy unit, in which the rash failed to appear until 10 days after treatment was started .
A targeted medical history and careful physical examination are the key steps towards achieving an accurate diagnosis, given that CP is primarily seen clinically.
There are usually no laboratory tests that can aid in the diagnosis of this medical entity, as cryofibrinogens and cryoglobulins tend to be negative ; a histopathological analysis of a biopsy sample harvested from a lesion is the sole means of confirmation of CP. A biopsy is usually ordered in diagnostically challenging cases of cold panniculitis. The following results are compatible with the disorder: