A 60-year-old woman with hypothyroidism, hypertension, and dyslipidemia presented with left-sided strabismus, diplopia, occasional ocular pain, and progressive left-sided proptosis over two years (Figure 1). Computed tomography (CT) revealed a well-circumscribed, intraorbital mass with ground glass appearance, suggestive of fibro-osseous lesion, unconnected to the adjacent bony structure (Figure 2). Surgical excision was performed, and histopathological analysis confirmed the diagnosis of fibrous dysplasia (Figure 3).

Fibrous dysplasia is a sporadic, non-hereditary genetic disorder resulting from a mutation in the GNAS1 gene located on chromosome 20, histologically characterized by the replacement of normal bone with fibro-osseous tissue.⁽¹⁾ The clinical presentation is variable and depends on the size and extension of the lesion and the relation to adjacent organs and structures. Management varies according to symptoms and lesion growth, with some patients requiring only observation while others may need pharmacological and/or surgical treatment.⁽²⁾

To our knowledge, only one other case of ectopic intraorbital fibrous dysplasia has been reported in scientific literature³. In that case, the authors speculated that the lesion originated from ectopic embryonic osteogenic cells or via differentiation of pluripotent stem cells within orbital adipose tissue – a rationale that may be applicable to the case described in our report.