than 6 mm.28 Diffuse choroidal hemangiomas are a part of neuro-oculo-cutaneous hemangiomatosis (Sturge-Weber syndrome). These tumors often are less elevated than the circumscribed, domeshaped lesions and can be mistaken for nonspecific retinochoroidal thickening. As a result, the retinochoroid layer thickness must be compared carefully between the two eyes in cases with Sturge-Weber syndrome.

On A-scan, choroidal hemangiomas exhibit high internal reflectivity with negligible attenuation. They are hyperechoic on B-scan with regular internal structure and little internal blood flow (Fig. 14). Serous retinal detachment at the tumor margins and calcification on the tumor surface may be present.28

Choroidal metastasis

Choroidal metastasis preferentially presents in the posterior pole as focal or multifocal lesions. They may be flat or dome-shaped, pigmented or nonpigmented, and unilateral or bilateral. They frequently are associated with serous retinal detachments. The internal reflectivity of metastatic carcinoma is typically medium to high with some

degree of internal irregularity that results from the varied histologic architecture (Fig. 15). Internal vascularity is minimal or absent. On B-scan, these lesions have irregular surfaces and often central excavations. The serous retinal detachment is often much more extensive with metastatic carcinomas than with a comparable-sized choroidal melanoma. Vitreous and subretinal hemorrhages rarely are associated with metastatic carcinoma. Some choroidal metastases present with atypical features such as low internal reflectivity and internal vascularity. The most common metastasis to produce these atypical findings is small cell carcinoma of the lung. Additionally, bullous choroidal detachments have been reported.29

Leiomyoma

Leiomyoma is a nonpigmented benign tumor that almost exclusively occurs in young women. Clinically, they can be differentiated from amelanotic choroidal melanoma by transillumination. Leiomyoma readily transilluminates, while choroidal melanoma does not. On B-scan, these lesions are smooth and dome-shaped. A scan shows