Malignant nerve sheath tumor of the ophthalmic nerve

Case Discussion

Ophthalmic nerve malignant nerve sheath tumor.

Histology

A resection of the left eye including an attached ovoid piece of skin superomedial to the eye.  The eye is 48mm superior to inferior, 42mm medial to lateral and 49mm anterior to posterior.  The ellipse of skin including the eyelashes anteriorly is 43mm medial to lateral and 9mm superior to inferior.  The attached  ovoid piece of skin is 92mm superomedial to inferolateral by 38mm. The medial 20mm of the left eyebrow is 20mm superomedial to the eyelashes.  Lateral to the eyebrow there is either a blood vessel or nerve, 15mm in length and 2-3mm in diameter.

Microscopic description

Sections show a nerve, which is thickened and largely replaced by markedly atypical spindle cells of similar appearance to tumor. 

Sections show a nerve containing occasional clusters of atypical spindle cells and a lymphoplasmacytic infiltrate.

Sections from the nodular and serpiginous lesion deep to the skin and posterior to the eye show a cellular tumor composed of spindle cells arranged in short fascicles and small whorled structures.  Cells have large, hyperchromatic pleomorphic nuclei with irregular nuclear routlines, prominent nucleoli and moderate amounts of elongate eosinophilic cytoplasm.  Mitoses are frequent, including atypical forms.  In areas, the tumor forms small nests of more epithelioid cells.  There is a patchy moderate lymphoplasmacytic infiltrate.  Some areas contain thick collagen fibers, probably entrapped reticular dermis.  Tumor is centered on the subcutis.  Tumor extensively involves adjacent nerves.  Some nerves appear completely replaced by tumor cells, with other nerves showing perineural spread.  In areas, the architecture is plexiform.  Tumor extensively involves the extrinsic nerves of the eye, posterior and medially, but is clear of the optic nerve.  Tumor involves the margin posterior to the eye, and involves the margin of the nerve described as lateral to the eyebrow. Tumor is 0.1mm from the lateral skin margin and 0.4mm from the deep skin margin.  The superior and medial skin margins appear clear.  No lymphatic or vascular space invasion is identified.

By immunohistochemistry, tumor cells are positive for S100, weakly positive for smooth muscle actin and negative for MelanA, HMB45, AE1/3 and desmin.

COMMENT: The plexiform nature of the tumor, and associated plexiform neurofibroma are highly suggestive of neurofibromatosis type 1.