SUBACUTE NODULAR MIGRATORY PANNICULITIS
Synonyms: Erythema nodosum migrans Chronic erythema nodosum
Key features
Nodules on the lower extremities that migrate or undergo centrifugal spread, with central clearing
Often unilateral
Most cases are idiopathic; occasionally associated with strepto- coccal infection or thyroid disease
More chronic course than typical erythema nodosum
History and Clinical Features
This condition was first described by Bafverstedt in 1954 and was named subacute nodular migratory panniculitis by Vilanova and Piñol Aguade in 1956. Some of its clinical and microscopic characteristics are similar to chronic erythema nodosum, and it is believed by many to represent a variant of the latter. However, others consider it to be a separate disorder. Subacute nodular migratory panniculitis is seen predominantly in women, is often unilateral, and is characterized by nodules that migrate or expand in a centrifugal manner (with central clearing) and may assume a yellowish or morpheaform appearance. Lesions tend to be less tender than those of classic erythema nodosum. There may be few, if any, associated systemic symptoms, though arthralgias have been reported and the ESR may be elevated. Most cases are idiopathic, but some are associated with streptococcal infection (as evidenced by elevated antistreptolysin O and anti-DNase B titers) or thyroid disease.
Pathology
Microscopically, the changes are those of a chronic septal panniculitis. However, in contrast to more classic forms of chronic erythema nodosum, subacute nodular migratory panniculitis shows greater septal thickening, more prominent granulomatous inflammation along the borders of widened subcutaneous septa, absence of phlebitis, and rare hemorrhage.
Treatment
Untreated, subacute nodular migratory panniculitis can last for months or years. However, treatment with potassium iodide is usually effective, resulting in clearing of lesions within several weeks.