Abstract
This case report presents a rare familial cluster of erythema nodosum
(EN) secondary to streptococcal infection in a 33-year-old Iranian woman
and her two children, aged 13 and 8 years. EN is a form of panniculitis
characterized by tender, erythematous nodules predominantly located on
the lower extremities. Although various triggers have been identified,
including infections, drugs, and systemic diseases, familial cases of EN
are infrequently reported. All three patients presented with painful,
erythematous nodules on the pretibial aspects of their lower legs,
preceded by respiratory symptoms. Laboratory investigations revealed
elevated antistreptolysin O (ASO) titers, leukocytosis, and increased
inflammatory markers, supporting the diagnosis of EN associated with
streptococcal infection. The temporal relationship between the onset of
respiratory symptoms and the development of EN in all three family
members suggests a shared environmental exposure to the streptococcal
pathogen. This case highlights the importance of considering familial
predisposition and common environmental exposures in the etiology of EN.
Furthermore, it emphasizes the value of a comprehensive clinical
evaluation and targeted laboratory tests in establishing the diagnosis
and identifying the underlying cause. Prompt recognition and appropriate
management of EN are crucial for optimal patient outcomes and the
prevention of potential complications. The familial occurrence of EN
underscores the need for further research to elucidate the genetic and
environmental factors contributing to the development of this rare
condition and to improve our understanding of its pathogenesis and
management.
Key words: Erythema nodosum, Familial, Streptococcus, Genetic,
Extremities