Erythema nodosum, a painful disorder of the subcutaneous fat, is the most common type of panniculitis. Generally, it is idiopathic, although the most common identifiable cause is streptococcal pharyngitis.Erythema nodosum may be the first sign of a systemic disease such as tuberculosis, bacterial or deep fungal infection, sarcoidosis, inflammatory bowel disease, or cancer.rythema nodosum nodules vary from 0.4 to 4 inches (1 to 10 cm) in diameter and are poorly demarcated, reflecting their subcutaneous anatomic location (Table 11â4; Figure 1) . Pretibial involvement is most common, although the extensor surfaces of the forearm, the thighs, and the trunk also may be affected.
xeric - being deficient in moisture; deserts provide xeric environments. 1  hydric - having or characterized by excessive moisture; a hydric habitat. 2  mesic - having or characterized by moderate or a well-balanced supply of moisture; mesic habitats.
A region is arid when it is characterized by a severe lack of available water, to the extent of hindering or preventing the growth and development of plant and animal life. Environments subject to arid climates tend to lack vegetation and are called xeric or desertic.