What is NOT one of the common causes of erythema nodosum according to the mnemonic NoDOSUM?

Erythema nodosum is an inflammatory condition characterized by painful, red nodules that typically appear on the lower legs. The mnemonic NoDOSUM helps to remember the common causes of this condition, which include several underlying diseases and factors.

The components of the mnemonic are particularly useful for recalling that drugs, sarcoidosis, ulcerative colitis, and other conditions can lead to erythema nodosum. While rheumatoid arthritis is an autoimmune condition that can present with skin changes, it is not traditionally listed among the most common causes of erythema nodosum.

Understanding the other elements of the mnemonic can provide insight into the classical associations of erythema nodosum. For instance, certain medications (like sulfonamides or oral contraceptives) and infectious diseases can precipitate this condition, as can systemic conditions like sarcoidosis and ulcerative colitis. This reinforces the idea that the connection between rheumatoid arthritis and erythema nodosum is less direct, which makes it an outlier compared to the other causes identified in the mnemonic.