Acinic cell carcinoma of the lacrimal gland

Case Discussion:

CT with contrast of the orbits demonstrates a large extraconal low density mass in the lateral aspect of the right orbit. It distorts and displaces the globe anteriorly. 

Its location and implied firm consistency suggest the most likely diagnosis is that of a tumour of the lacrimal gland (rather than lymphoma or pseudotumour which tend to be softer and not distort the globe). 

In this case resection demonstrated an acinic cell carcinoma of the lacrimal gland which is very rare. 

Microscopic Description

The right lacrimal gland tumour demonstrates a neoplasm, which contains numerous papillae of neoplastic cells, and cystic spaces, which frequently contain degenerated blood and exfoliated cells. The cells are arranged in a variety of patterns, including solid, papillary and microfollicular. The cells have abundant eosinophilic cytoplasm, which is focally finely granular. Numerous cells containing small to large vacuoles are present.

Cells on the surface of the papillae frequently show a "tombstone" appearance. On PAS and Diastase stains occasional cells show faint granular staining and occasional small glands containing PAS positive material are present.

The tumour is surrounded by a fibrous capsule of varying thickness. Tumour focally infiltrates into the capsule and just up to beneath the painted resection margin. The tumour stains strongly for keratin, which highlights the invasive features at the margin of the tumour. Immunoperoxidase stains for smooth muscle actin, S100, P63 and GFAP are negative. 

The histologic features of this tumour are characteristic of an acinic cell carcinoma which is extremely rare within the lacrimal gland with only a handful of cases having been reported in the literature.