Ultrastructural pathology of melanomalytic glaucoma

Area of Science:

• Ophthalmology
• Oncology
• Pathology

Background:

• A patient presented with a heavily pigmented ciliary body tumor, diffuse iris and chamber angle pigmentation, and secondary open-angle glaucoma.
• Clinical diagnosis suggested malignant melanoma and melanomalytic glaucoma, leading to enucleation of the eye.

Observation:

• Histopathology, immunohistochemistry, and ultrastructural studies revealed a spindle cell tumor with extensive necrosis and a significant macrophagic response.
• The iridocorneal angle showed heavy infiltration by pigmented cells, identified as melanomacrophages, consistent with previous descriptions.
• Trabecular endothelial cells had phagocytosed melanin but maintained structural integrity, showing signs of activation.

Findings:

• The primary finding was a spindle cell ciliary body melanoma causing secondary open-angle glaucoma.
• Massive infiltration of the iridocorneal angle by melanomacrophages was observed, leading to mechanical obstruction of aqueous humor outflow.
• Tumor cells were also identified on the iris surface and in the trabecular meshwork, indicating potential spread.

Implications:

• This case reinforces the understanding of melanomalytic glaucoma as a mechanical process secondary to pigment dispersion and macrophage infiltration.
• The presence of tumor cells in the anterior chamber highlights the importance of considering tumor spread in managing uveal melanomas with glaucoma.
• Findings have implications for the clinical management of anterior uveal melanomas complicated by secondary open-angle glaucoma.