Conjunctival myxoid stromal tumour: a distinctive clinicopathological and immunohistochemical study.

BACKGROUND/AIMS: To describe the clinicopathological and immunohistochemical characteristics of 10 patients representing a new entity of benign conjunctival myxoid stromal tumours.

METHODS: Retrospective review of clinical findings, histopathological and immunohistochemical studies identified 10 cases of low-grade conjunctival myxoid stromal tumours. Specimens were routinely processed and stained with H&E. Immunohistochemical stains for CD34, CD68, vimentin, S100, smooth muscle actin (SMA), myosin, desmin, actin, Bcl-2 and Ki-67 were performed. Specific stains for Alcian-blue periodic acid-Schiff (AB-PAS) and aldehyde fuchsin stains were also performed.

RESULTS: Ten patients with an average age of 45.6±11.1 years had a tender white or faint yellow to red mass on the bulbar conjunctiva. All the lesions were completely removed, and none of the patients relapsed. Histologically, all neoplasms consisted of spindle-shaped cells that showed signs of pseudonuclear inclusions, multinuclear cells and had no atypia. The stroma consisted of a large amount of mucus and was infiltrated with delicate to ropey collagens, a few mast cells and new vessels. Immunohistochemical stains were positive for CD34, vimentin and Bcl-2; partial positive for CD68; very low for Ki-67; and negative for S100, SMA, myosin, desmin and actin. AB-PAS suggested that the stroma was mucinous.

CONCLUSIONS: These rare benign mesenchymal conjunctival tumours are mostly unilateral and occur in the bulbar conjunctiva. Complete resection is the radical treatment. These lesions are characterised by multiple spindle cells, a large amount of mucus, and sharing similar basic histopathological features with conjunctival myxoma and conjunctival stromal tumour. We suggest naming these lesions 'conjunctival myxoid stromal tumours'.