Uveal melanoma classification
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Simrat Sarai, M.D. [2]
Overview
Uveal melanoma may be classified into several subtypes based on their location and based on the cell type. According to the Callender classification, there are four subtypes of uveal melanoma based on the cell type. Based on their location uveal melanoma may be classified into two subtypes.
Classification
Uveal melanomas may arise from any of the three parts of the uvea, and can be divided into two categories.[1]
- Anterior uveal melanomas
- The tumor arises in the iris
- Posterior uveal melanomas
- The tumor arises in either the choroid or the ciliary body. Intraocular melanomas simultaneously can involve more than 1 uveal structure.
Classification based on size
According to Collaborative Ocular Melanoma Study Group, there are three types of uveal melanoma based on tumor size.[2]
- Small melanomas are 1.0 - 2.5 mm in apical height and > 5.0 mm in largest basal dimension
- Medium tumours are defined as tumours 2.5 to 10 mm in apical height and ≤ 16 mm in largest basal diameter.
- Large tumours are ≥ 2 mm in apical height and > 16 mm in maximal basal diameter, or a melanoma > 10 mm in apical height, regardless of the basal diameter.
Classification based on cell type
Uveal melanomas originate from melanocytes in the uveal tract. According to the revised Callender classification there are four distinct cellular types.[3]
- Spindle-A cells (spindle-shaped cells with slender nuclei and lacking visible nucleoli).
- Spindle-B cells (spindle-shaped cells with larger nuclei and distinct nucleoli).
- Epithelioid cells (larger polygonal cells with one or more prominent nucleoli).
- Intermediate cells (similar to but smaller than epithelioid cells).
Most primary intraocular melanomas contain variable proportions of epithelioid, spindle-A, and spindle-B cells (mixed-cell melanomas). Pure epithelioid-cell primary melanomas are infrequent (approximately 3% of cases). In the Collaborative Ocular Melanoma Study, mixed-cell type melanomas predominated (86% of cases).
References
- ↑ Uveal melanoma. Wikipedia(2015) https://en.wikipedia.org/wiki/Uveal_melanoma Accessed on October 20, 2015
- ↑ van, J.G.M.; Koopmans, A.E.; Verdijk, R.M.; Naus, N.C.; de, A.; Kilic, E. (2013). "Diagnosis, Histopathologic and Genetic Classification of Uveal Melanoma". doi:10.5772/53631.
- ↑ Uveal melanoma. National Cancer Institute(2015) http://www.cancer.gov/types/eye/hp/intraocular-melanoma-treatment-pdq#section/_95 Accessed on October 20 2015