Nodular fasciitis (NF) is an uncommon and benign tumour-like fibroblastic proliferation that is difficult to distinguish from sarcoma both clinically and histologically. In addition, it is a type of lesion characterised by having a potential for spontaneous regression. NF is frequently misdiagnosed due to its rapid growth, rich cellularity, and mitotic figure. Although NF is only rarely diagnosed in children, the head and neck represent the most common locations for NF among this population. The cause of NF remains unknown, however trauma is believed to be an important triggering factor. We describe an unusual case of NF in the posterior ethmoid sinus in a six-year-old boy with no history of trauma. The NF was incidentally noted on a computed tomography scan after the patient complained of a squint. The diagnosis of NF was also supported by histopathology and specific immunohistological staining. A surgical biopsy was performed, and no recurrence was observed after one year.