Metastatic Tumors
Metastatic lesions are the most common intraocular tumors in adults. These lesions most often involve the choroid, but any ocular structure can be affected. Unlike primary uveal melanoma, metastatic lesions are often multiple and may be bilateral. Although these lesions typically assume a flattened growth pattern, rare cases of collar-button or mushroom-shaped lesions have been reported. The most common primary tumors metastasizing to the eye are breast carcinoma in women and lung carcinoma in men (Fig 12-22), although tumors from many different primary sites have been reported. Histologically, metastatic tumors may recapitulate the appearance of the primary lesion, or they may appear less differentiated. Special histochemical and immunohistochemical stains can be helpful in diagnosing the metastatic lesion and determining its origin. The importance of a careful clinical history cannot be overemphasized. See Chapter 20 for further discussion.
Other Uveal Tumors
Hemangioma
Hemangiomas of the choroid occur in 2 specific forms. The localized choroidal hemangioma typically occurs in patients without systemic disorders. The diffuse choroidal hemangioma is generally seen in patients with Sturge-Weber syndrome (encephalofacial angiomatosis).
Histologically, both the diffuse and localized hemangiomas show collections of variably sized vessels within the choroid (Fig 12-23). The lesions may appear as predominantly capillary hemangiomas or cavernous hemangiomas or a mixed pattern. The adjacent and overlying choroid may show compressed melanocytes, hyperplastic RPE, and fibrous tissue proliferation. See also Chapter 18 and Figures 18-1 and 18-2 in this volume and BCSC Section 12, Retina and Vitreous.
Figure 12-22 A, Clinical appearance of a metastatic lesion from a primary lung tumor. B, Gross appearance of lesion (between arrowheads). C, Choroidal metastasis from lung adenocarcinoma; histology shows adenocarcinoma (between arrows) with mucin production (asterisk). Note overlying retinal detachment. D, Higher magnification depicts a welldifferentiated adenocarcinoma with distinct glandular appearance. (Courtesy of Hans E. Grossniklaus, MD.)
Figure 12-23 Choroidal hemangioma with a large number of thin-walled, variably sized vessels within the choroid. A, Lowmagnification view illustrating exudative retinal detachment overlying the lesion (asterisk). Arrows designate the Bruch
membrane. B, Higher magnification; arrows designate Bruch membrane. (Courtesy of Nasreen A. Syed, MD.)
Choroidal osteoma
Choroidal osteomas are benign bony tumors that typically arise from the juxtapapillary choroid and are seen in adolescent to young adult patients, more commonly in females. The characteristic lesion appears yellow to orange and has well-defined margins (see Chapter 17, Fig 17-13). Histologically, the tumor is composed of compact bone located in the peripapillary choroid. The intratrabecular spaces are filled with a loose connective tissue containing large and small blood vessels, vacuolated mesenchymal cells, and scattered mast cells. The bony trabeculae contain osteocytes, cement lines, and occasional osteoclasts. See Chapter 17 for further discussion.
Lymphoid proliferation
The choroid may be the site of lymphoid proliferation, either as a primary ocular process or in association with systemic lymphoproliferative disease.
Uveal lymphoid infiltration (formerly reactive lymphoid hyperplasia) of the uveal tract is similar to the spectrum of low-grade lymphoid lesions that occur in the orbit (see Chapter 14) and conjunctiva. There may be diffuse involvement of the uveal tract by a mixture of lymphocytes and plasma cells, and lymphoid follicles may be present. In addition, there may be a similar infiltrate located along the posterior episclera. Lymphocyte typing reveals a polymorphic population without clonal restriction; this finding distinguishes inflammatory pseudotumor from lymphoma.
Lymphoma of the uveal tract occurs almost exclusively in association with systemic lymphoma (Fig 12-24) as an extranodal site. The classification of lymphomas is discussed in Chapter 14.
Grossniklaus HE, Martin DF, Avery R, et al. Uveal lymphoid infiltration: report of four cases and clinicopathologic review. Ophthalmology. 1998;105(7):1265–1273.
Figure 12-24 A, Diffuse expansion of choroid by lymphoma. R = RPE, S = sclera. B, Higher magnification depicts atypical
lymphocytes. (Courtesy of Hans E. Grossniklaus, MD.)
Neural sheath tumors
Neurilemomas (schwannomas) and neurofibromas are rare tumors of the uveal tract. Multiple neurofibromas may occur in the ciliary body, iris, and choroid in patients with neurofibromatosis. The histopathologic features of these tumors are discussed in Chapter 14.
Leiomyoma
Neoplasms arising from the smooth muscle of the ciliary body have been reported only rarely. When they occur, they may be confused with amelanotic melanoma or neurofibroma clinically.