Orientation of eye structures.
The choroidal melanoma exhibits a mushroom-like growth.
Our esteemed P.A. demonstrates the proper technique of preparing the section.
Which would yield this specimen with all the preserved structures.
The globe is serially sectioned for optimal histology. Having correctly sized cassettes is important.
The tumor undermines the retina, leading to retinal detachment.
This image demonstrates the relationship of the tumor to retina (pigmented wavy line on the left side of image).
These melanoma cells are best classified as type B spindle cells. Scattered melanin pigment can be appreciated.
Note the vesicular nuclei and prominent single nucleoli (characteristic of type B spindle cells).
Uveal melanoma is the most common primary intraocular malignant tumour, with an annual incidence of approximately 6 cases per million (Singh). Choroidal melanoma is a subtype of uveal melanoma. The uvea is composed of iris, ciliary body and choroid. Primary choroidal melanoma arises from melanocytes within the choroid (and not from the pigmented retinal epithelium).
Grossly, choroidal melanomas commonly exhibit a discoid, collar-button or mushroom-shaped growth (McLean). Histologically, the melanoma cells are either spindled or epithelioid, the latter being a poor prognostic factor. The spindle cells are further subclassifed as type A or type B. Type B cells are larger than type A, and contain prominent nucleoli (Garcia-Valenzuela).
Enucleation and globe-sparing therapies appear to have similar success rates.
The tumor most commonly metastasizes to the liver and up to 40% of patients with posterior (choroidal) uveal melanoma develop liver metastasis by 10 years (Singh). Other prognostic factors include location (iris melanomas have the best prognosis and ciliary body melanomas have the worst) and cytomorphology(epithelioid histolgy is a poor prognostic factor). Mitotic activity, tumor size, the presence of extrascleral extension and tumor infiltrating lymphocytes are also significant prognostic factors (McClean, Singh).
Garcia-Valenzuela E. Choroidal Melanoma: eMedicine. Last updated on May 2011. Available at: emedicine.medscape.com/article/1190564-overview#a1
McLean IW, Saraiva VS, Burnier MN Jr., Pathological and prognostic features of uveal melanomas. Can J Ophthalmol. 2004 Jun;39(4):343-50.
Singh AD, Shields CL, Shields JA. Prognostic factors in uveal melanoma. Melanoma Res. 2001 Jun;11(3):255-63.
***Gross photos courtesy of Myra Zucker, Dept of Pathology, Albuquerque New Mexico.