A 4-year-old patient referred to the ophthalmology department in June 2008 from paediatrics, with a diagnosis of congenital ptosis of the left eye, which according to the parents had been evident since the age of two. The parents report that she tends to rub that eye a lot. Normal pregnancy, at term by caesarean section. Only the mother's coagulation problems during pregnancy, treated with subcutaneous heparin, stand out.
Examination revealed a slight asymmetry between the upper eyelids, with the inner third of the left upper eyelid slightly lowered. No masses were palpable in this area. Visual acuity was 0.8 in both eyes with Snellen's E test. Ocular motility normal, Cover test negative. Fundus examination was unaltered.
The patient was seen again five months later, reporting itching in the left eye. The new examination revealed a discreet bulge in the inner third of the upper eyelid of the left eye. There was no clear limitation of the motility of the left eye, but it appeared to be slightly hypotropic. The rest of the examination was normal. A differential diagnosis of motility disorder or orbital mass was suggested. An assessment by paediatric ophthalmology was decided and an imaging technique was requested.

In the consultation with the paediatric ophthalmology department a week later, uncorrected visual acuity of 1 in the right eye and 0.7 in the left eye was observed, which at 1.25 at 40o reached unity. Negative cover test in primary position with discrete limitation to adduction and elevation, normal stereopsis and fundus without alterations. Palpation revealed a mass in the inner third of the upper eyelid. During the waiting period until the magnetic resonance imaging (MRI) was performed, the astigmatism increased.
The MRI showed a tumour in the superointernal angle of the left orbit, compressing the eyeball, compatible with a dermoid cyst, and surgical treatment was indicated. An anterior orbitomy was performed through the inner third of the palpebral fold. Intraoperatively, a well-defined lesion was detected in the superointernal orbital quadrant, which was removed in its entirety. One week after the operation, symmetry between both upper eyelids and eye position were restored.