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.
1 Often, x-rays. a form of electromagnetic radiation, similar to light but of shorter wavelength and capable of penetrating solids and of ionizing gases.  such radiation having wavelengths in the range of approximately 0.1â10 nm.