Cutaneous malignant melanoma metastatic to the vitreous

Differentiation between Melanin-Laden Macrophages and Melanoma Cells in Vitreous Aspirates

OBJECTIVE

The differential diagnosis between retinal detachment and melanoma metastatic to the vitreous can be challenging, both clinically and cytologically. We demonstrate the diagnostic features and pitfalls of the cytological assessment.

STUDY DESIGN

A case of a metastatic melanoma to the vitreous is compared to a case of retinal detachment initially suspected as melanoma metastasis. Case 1 was a 54-year-old patient with a vague history of pigmented lesions 20 years previously and a current presentation of a visual defect. Case 2 was a 68-year-old patient with a history of melanoma and a presentation of floaters and flashing lights.

RESULTS

The vitreous fluid of case 1 contained atypical, pigment-laden cells positive for HMB-45 and assessed as melanoma. On enucleation, a melanoma metastatic to the vitreous was diagnosed. The vitreous fluid of case 2 revealed atypical cells containing pigment granules. The cells were negative for melanocytic markers, while the granules stained positive for melanin. Macrophage marker CD163 was positive in all cells. The interpretation was one of macrophages reactive to the retinal detachment.

CONCLUSION

Melanin-laden macrophages can mimic melanoma cells. This needs to be considered in the differential diagnosis. Additional stains can help the distinction.

Cutaneous melanoma metastatic to the vitreous cavity

PURPOSE

To report a case of cutaneous melanoma metastatic to the vitreous cavity.

METHODS

Retrospective case report. A 72-year-old white man with a history of cutaneous melanoma but no known distant metastases presented with floaters and decreased vision.

RESULTS

The patient was initially treated for a presumptive diagnosis of ocular toxoplasmosis. After failure to respond to treatment, he underwent diagnostic pars plana vitrectomy. Pathology of the vitreous specimen was suggestive of metastatic melanoma, and systemic workup revealed metastases to the brain.

CONCLUSION

In patients with a known history of cutaneous melanoma presenting with ocular inflammation, a high index of suspicion for metastatic disease should be maintained.