**7. Conclusion**

OFG is an uncommon immunologically mediated disorder with unknown etiology that affects the soft tissues of the oral and maxillofacial region. Although the precise cause of OFG is still unknown, allergy, infection, and genetic predisposition as well as immunological reaction have been suggested as probable causes that can be effective in pathogenesis of OFG. Clinical features of OFG are nonspecific, and various presentations in disease make it difficult to diagnose, so a comprehensive clinical, laboratory, and microscopic evaluation is required for exact diagnosis and treatment [28]. A number of granulomatous disorders, such as deep fungal infections, tuberculosis, angioedema, leprosy, Wegener's granuloma, Crohn's disease, and sarcoidosis, are similar to OFG in clinical features specifically persistent lip swelling, so differential tests are needed for diagnosis of OFG [33]. Because of similarity between OFG and some of the granulomatous diseases, this point arises that whether or not OFG is a distinct clinical disorder [12]. In this context, further studies are needed to differentiate OFG from this group of disorders.
