A Case of a Cavitary Iris Melanoma with Aqueous Cytological Modulation

Abstract

Malignant melanoma is the most common primary malignant tumour of the iris, but represents a small proportion of all uveal melanomas. The authors describe a 34-year-old male with a pigmented lesion of the iris. The lesion remained stable for 7 years, but the patient re-presented after this time with sudden enlargement of the mass and hyphaema. Excisional biopsy confirmed cavitary melanoma of the iris. This is the first reported case of cavitation in a primary iris melanoma. The patient has not had any further adjuvant treatment and remains metastasis free at 5 years of follow-up.

Keywords: Iris cyst; Iris melanoma; Uveal melanoma.

Fig. 1

a Right pupillary margin lesion at presentation: a 3-mm dumbbell-shaped mass covered with pigmented epithelium from the back surface of the iris encroaching on the pupil and a 3 × 2.5 mm partially melanotic lesion entering the anterior chamber from the front of the iris. This lesion had enlarged feeder vessels and a slight dusting of pigment spread 1 mm from the lesion but not reaching the edge of the iris or angle on gonioscopy. b Four years after presentation, the lesion was noted to have slow growth, gradually encroaching the visual axis, although vision remained stable. c, d A haemorrhagic outgrowth from the inferotemporal edge of the retroiridal portion of the lesion.

Fig. 2

Transverse ultrasound biomicrosopy images from 4: 00 in the right eye. a At initial presentation, a solid mass arising from the iris stroma centrally with a small cavitation at the pupillary portion of the lesion can be seen. b After rupture of the cyst, prominence of the pupillary portion of the mass is visible, with larger lucencies involving the posterior iris stroma.

Fig. 3

Histology. a Haematoxylin and eosin (H&E)-stained section showing three zones. The asterisk represents the solid melanoma, the larger arrow shows the cavitary component, and the smaller arrow the pigment epithelial cyst component. b Higher power of a showing the cavity marked by the asterisk and melanoma constituting the walls of the cavity. c H&E-stained section of the cytological detail of the solid melanoma area. The nuclei show varying chromasia and size variation. Some contain nucleoli. Melanin pigment is present. d H&E of the melanoma lining the cavity shows similar cytological features to c. e H&E showing melanoma several cell layers thick lining the iris pigment epithelium. f H&E showing melanoma cells up to 2 cells thick (arrow) lining the iris pigment epithelium. g H&E showing just iris pigment epithelium without a tumour lining. h Melanoma cells on the anterior iris surface showing smaller cell size (upper plate) compared to deeper melanoma cells (lower plate). i, j Cyclin D1 immunohistochemistry showing many more nuclei positive in the deeper, larger melanoma cells, compared to the surface, smaller melanoma cells.