Exophthalmos is the most commonly known symptom of orbital tumors in adults and children [
2] and is, usually easy to recognize, and always brings to mind the possibility of a neoplasm. Conversely, if a few cases have been described in adults [
1,
3‐
5], there is only very little knowledge of the association between enophthlamos and orbital tumors in children [
2] ; because of the scarcity of both entities and the difficulty in clinically objectivizing this symptom. In fact, enophthalmos is a posterior displacement of the eyeball within the orbit but its diagnosis is tricky because there is no agreement on a clear definition, especially in children. For example, Yip set a 14 mm limit [
6] while diagnosis is not made formal until after orbital CT scan measures an oculo-orbital index (OOI) < 30 % (OOI = Prebicanthal eyeball length/overall eyeball length x100). Nonetheless, a large majority of specialists agree on the importance of clinical and exophthalmometric judgment over imaging assessment.
When this symptom is identified, the next step is to rule out differential diagnoses: contralateral proptosis, ipsilateral ptosis (including Horner syndrome), microphthalmia and phthisis bulbi.
Once those are excluded, the cause needs to be sought. MacFaul stated in his “System of ophthalmology” that unlike exophthalmos
, enophthalmos could not lead to a fatal outcome [
7]; because his classification failed to mention orbital tumors as a possible etiology. He stated that orbit topography is such that infiltrative processes are more likely to push outwards and induce proptosis [
3]. Most of the time, this statement is true, however in rare cases; neoplastic cells can infiltrate extraocular muscles, alter orbital fat structure and destroy bony architecture leading to a backwards eyeball traction [
4].
Based on this, three possible mechanisms have been suggested to explain the occurrence of enophthalmos [
4]. First, structural modifications: post traumatic bone fractures, congenital bony defects; silent sinus syndrome and tumors can crack the orbit wall and modify the eyeball position [
4,
5]. Second: eyeball backwards retraction consecutive to muscle and/or fat tissue infiltration [
4,
5]. Fitting into this category are adult cases of enophthalmos, which can reveal various types of orbital neoplasms. Affected patients are usually females with breast cancer [
1,
5]. When the musculature is invaded, areas of fibrosis are created causing posterior traction of the eyeball. In such cases, enophthalmos is usually not isolated and is associated with a palpable mass, impaired eye motility, diplopia, orbital pain, drooping of the upper eyelid etc.. [
1,
3‐
5]. Third: fat atrophy (such as in senile fat atrophy and orbital varices) might induce an eyeball displacement by shrinking the orbital content [
4,
5].In the present case, the three mechanisms could have caused a posterior displacement of the eyeball. By cracking the orbital wall (Figure
1b), the neuroblastoma modified the eyeball position dragging it downwards and backwards. Additionally, the orbital cavity seemed to be increased on the right side as compared with the left side. In Figure
1b, the osteolytic process induced fractures of the right orbit’s inferior wall and osteocondensation with bone neoformation at the superior wall of the left orbit associated with soft tissue inflammation, which denotes less space available for the right globe as compared with the left globe, possibly explaining the enophthalmos of the right eye. Additionally, muscle and fat infiltration by the neuroblastoma could have induced local areas of retractile fibrosis pushing the globe backwards, as shown in Figure
1b where the right globe seems to be smaller than the left globe whereas the cross-section is perfectly vertical, denoting a backwards retraction of the right eye. Third, (though this is probably less likely), the growth of the neuroblastoma could have induced a shrinking of the orbit’s other components including fat. As seen in Figure
1a, the orbital content is less prominent in the right side as compared to the left side, causing a backwards displacement of the eye.