Discussion
This case report presents a rare familial cluster of EN secondary to streptococcal infection, involving a mother and her two children. EN is the most common form of panniculitis, characterized by tender, erythematous nodules predominantly located on the anterior aspects of the lower extremities (9, 10).Although the exact pathogenesis of EN remains unclear, it is considered a delayed hypersensitivity reaction to various antigenic stimuli, including infections, drugs, systemic illnesses, and malignancies (3, 11).
The clinical presentation of EN in this familial cluster is consistent with the typical features described in the literature, including the acute onset of painful, erythematous nodules on the lower extremities (6, 12). The presence of associated systemic symptoms, such as fever and arthralgia, is also commonly reported in EN (13). The diagnosis of EN is primarily based on the characteristic clinical findings, although a deep incisional or excisional biopsy may be performed to confirm the diagnosis and exclude other nodular lesions (3, 6).
Compared to the previous case report of EN, this familial cluster presents a unique perspective on the potential genetic predisposition and shared environmental factors contributing to the development of the condition (14, 15). Familial EN is a rare subset of the disease, and its exact prevalence remains unknown (16).The occurrence of EN in multiple family members within a short time frame, as seen in this case, strongly suggests a common triggering factor, such as streptococcal infection (2).
The temporal relationship between the onset of respiratory symptoms and the subsequent development of EN in all three family members supports the role of streptococcal infection as the underlying cause. Streptococcal pharyngitis is the most common identifiable cause of EN (9, 17),and the elevated antistreptolysin O (ASO) titers in the patients further support this etiology (2, 18).
The familial occurrence of EN in this case highlights the importance of considering a family history in the diagnostic evaluation and management of the condition (19). Genetic factors may play a role in the susceptibility to EN, as suggested by the presence of human leukocyte antigen (HLA) alleles in some familial cases [6,16]. However, the specific genetic markers associated with familial EN remain to be elucidated (9, 15).
In addition to genetic predisposition, shared environmental exposures may contribute to the development of EN in family members (20). The proximity of family members and the potential for transmission of infectious agents, such as streptococcal bacteria, may explain the clustering of EN cases within families (2, 20).
The management of EN primarily focuses on identifying and treating the underlying cause, if present (9, 12). Supportive measures, such as rest, leg elevation, and the use of nonsteroidal anti-inflammatory drugs (NSAIDs) or potassium iodide, can help alleviate symptoms (9, 21). In severe or refractory cases, systemic corticosteroids may be considered (21). Furthermore, patients should be monitored for potential complications or associated systemic diseases, particularly in the setting of chronic or recurrent EN (22, 23).