Iris Mammillations as the Only Sign of Ocular Melanocytosis in a Child With Choroidal Melanoma

An 8-year-old girl had visual loss in her left eye over 2 months. Ocular examination showed that visual acuity was counting fingers in the left eye. The left iris was moderately pigmented and thickened with numerous confluent, dome-shaped elevations on its surface, consistent with iris mammillations arising from ocular melanocytosis. There was total retinal detachment and an inferiorly located large amelanotic choroidal mass compressing the optic nerve. A specimen from a fine-needle aspiration biopsy showed spindle and epithelioid melanoma cells. The eye was enucleated. Pathologic examination showed that the bland melanocytes comprising the anterior border layer of iris formed focal aggregates, corresponding to the iris mammillations observed clinically. The uvea was diffusely thickened. Arising from the posterior choroid and obscuring the optic nerve head was a moderately pigmented spindle and epithelioid cell choroidal melanoma with diffuse lymphocytic infiltration and high mitotic activity. This case demonstrates that iris mammillations can be the initial manifestation of ocular melanocytosis in the absence of scleral pigmentation.

The occurrence of uveal melanoma in patients younger than 20 years is rare, accounting for approximately 1% of all uveal melanoma cases.¹ Congenital ocular melanocytosis is the most common predisposing factor for the development of uveal melanoma in children as well as in adults.²

We describe an 8-year-old girl who had choroidal melanoma associated with congenital ocular melanocytosis characterized primarily by the presence of numerous prominent iris mammillations.

An 8-year-old girl developed visual loss in her left eye over 2 months. On examination, the visual acuities were 20/20 OD and counting fingers OS. The right eye was normal. Anterior segment examination of the left eye showed that the conjunctiva and sclera were normal. The iris was moderately pigmented and thickened and there were numerous elevated protuberances on the iris surface, compatible with iris mammillations. Ophthalmoscopy disclosed total retinal detachment and an inferiorly located amelanotic multilobulated choroidal mass measuring 18 × 16 mm in basal diameter and 9.6 mm in thickness. The choroidal lesion compressed and completely obscured the optic nerve.

Ultrasonography (A- and B-scan) showed medium internal reflectivity, acoustic hollowness, and intrinsic vascular pulsations in the choroidal mass. Fluorescein angiography demonstrated early and late hyperfluorescence within the lesion. The primary diagnoses considered were choroidal melanoma or large choroidal granuloma. A fine-needle aspiration biopsy of the choroidal mass was performed. Cytopathologic examination disclosed spindle and epithelioid cells that contained melanin and were consistent with malignant melanoma. The left eye was enucleated and a hydroxyapatite sphere was implanted.

Macroscopic examination of the left eye showed that the uvea was diffusely thickened. There were numerous mound-shaped protuberances with roughly stellate bases on the left iris surface, corresponding to the iris mammillations observed clinically (Figure 1). Microscopically, the iris stroma was quite cellular, with an infiltration of spindle-shaped melanocytes with bland nuclear features. The melanocytes comprising the anterior border layer of iris formed focal aggregates, consistent with iris mammillations (Figure 2). Arising from the posterior choroid and obscuring the optic nerve head was a moderately pigmented choroidal melanoma. The tumor was composed of a mixture of epithelioid and spindle melanoma cells with diffuse lymphocytic infiltration.

The patient was systemically followed up at 6-month intervals. One year after enucleation, the patient developed liver and pancreas metastases and is now undergoing chemotherapy for metastatic melanoma.

Iris mammillations are dark brown, smooth, mound- or dome-shaped protuberances that are typically found on the anterior surface of a diffuse iris nevus or deeply pigmented iris.^3,4 Iris mammillations are most often found in patients with ocular melanocytosis, as in our patient. They can also occur as an isolated finding. The differential diagnosis of iris mammillations includes Lisch nodules seen in neurofibromatosis, ocular and oculodermal melanocytosis, tapioca malignant melanoma of the iris, inflammatory iris granulomas, and the Cogan-Reese or iris nevus syndrome variant of the iridocorneal endothelial syndrome.⁴

Iris mammillations are presumed to be congenital in origin and can be the initial sign of ocular melanocytosis.³ Our patient with iris mammillations had intraocular melanocytosis, which probably predisposed to the development of uveal melanoma. In contrast, some patients with iris mammillations never develop clinical signs of periocular, scleral, or intraocular melanocytosis.^4,5 This observation suggests that iris mammillations can also represent a limited form of ocular melanocytosis. The development of uveal melanoma has not been reported in this group of patients with iris mammillations and no other sign of ocular and oculodermal melanocytosis.^4,5

In conclusion, iris mammillations can be the initial sign of ocular melanocytosis in younger patients. Because ocular melanocytosis is a risk factor for uveal melanoma, regular follow-up is necessary in these patients to identify the development of uveal melanoma.

Accepted for publication January 4, 2000.

This research was supported by the Paul Kayser International Award of Merit in Retina Research, Houston, Tex (Dr J. Shields); the Eye Tumor Research Foundation, and the Noel T. and Sara L. Simmons Endowment for Ophthalmic Pathology, Wills Eye Hospital, Philadelphia, Pa.

Corresponding author: Carol L. Shields, MD, Oncology Service, Wills Eye Hospital, 900 Walnut St, Philadelphia, PA 19107.