Teaching Case

The patient presented with swollen left eye and hanging down of the upper-eyelid on the left side.

The 56 year old male patient presented with hanging down of the upper eyelid on the left side, the left eye was swollen and the pupila was covered to the middle. The lower eyelid was thickened and swollen, especially in the temporal region. The tumor mass was not painful or moveable. Only lifting in adduction was possible, the abduction was not possible. The conjunctiva was thickened, chemotic and hypervascularised. The caruncula lacrimalis was also thickened and hypervascularised. There was orange-brown pigmentation of iris between 11-13 hour. The cornea was clear with incipient vascularisation. Papilla was inconspicuous. Anophtalmus at the right side in consequence of enucleation because of tumor of not known genesis 30 years ago. There was an suppurative secretion of the right conjunctiva.

MR of the orbita and cranium showed an smooth narrowed, round to oval, extraconal expansion 3x2x3cm (axilar x sagittal x craniocaudal) in the fronto-caudal eyelid region of the left orbita between the, to the medial displaced, bulbus oculi and os zygomaticum. The laterocranial part was reaching the pars palpebralis of gl. lacrimalis.
The orbital septum was not demarcated. M. rectus lateralis was cranial displaced.
This lesion had slightly higher signal on the T1-FS sequences then muscles, and on T2 WI relative hypointense signal. After application of gadolinium, this lesion had moderate enhancement. There were no signs of bony wall destructions.

Orbital melanocytoma is rare benign pigmented tumor of neuroectodermal genesis. MRI of orbita is important in showing the anatomical extent of the tumor mass. T1 WI showed slightly hyperintense Signal and moderate postcontrast enhacement, Precontrast T2 WI showed hypointense Signal. Differential diagnosis is important to distinguished this tumor from other preseptal and extraconal tumors, such as lymphoid hyperplasia (NHL), adenoidcystic lacrimal carcinoma, hemangiopericytoma, benign mixoid lacrimal tumor, dermoid or epidermoid.

Immunhistochemistry findings are decisive in differential diagnosis to malign melanoma. Reactivity with antibodies of S-100 protein and HMB 45, and also antibodies of Synaptophysin, Chromogranin and NCAM, are common. Chemotherapy is normally not needed. Surgical approach is treatment of choice.