Ординатура / Офтальмология / Английские материалы / Clinical Ophthalmic Echography_Harrie_2008

Shields states, “most uveal melanomas have little tendency to invade the optic disc. Even tumors that are adjacent to the disc tend to stop abruptly at the optic disc margins.” He adds that some melanomas with a diffuse growth pattern have a tendency

to grow into the substance of the nerve and can be confused with papilledema. Such tumors have an extremely poor prognosis.55 This frequency of nerve invasion is in contrast to retinoblastoma, in which an incidence of 29% is reported.56

NA is a 67-year-old woman who noted a drop in the vision in her right eye, but delayed seeking medical attention for several months. She was finally seen by an ophthalmologist who documented vision in that eye of 20/70-2 and 20/30 in the left eye. A 2+ afferent defect was noted. Fundus examination showed a darkly pigmented lesion adjacent superiorly to the optic nerve. Echography was performed and revealed a low-to-medium reflective tumor measuring 4.2 mm in thickness and 13.8 mm in basal diameter (Fig. 279). The optic nerve was measured by A-scan to be 2.66 mm, which is within normal limits.

Because of the poor visual acuity and the presence of an afferent defect, the patient was referred for an MRI scan of the optic nerve. It demonstrated slight nonspecific enhancement after the administration of a contrast agent. The patient chose to have the eye enucleated as opposed to exenteration. Every effort was made to obtain a long segment of the retrobulbar optic nerve. The pathological report showed that the surgical margin at the distal end of the optic nerve segment was clear and only the anterior part was invaded by melanoma cells.

Choroidal melanomas will uncommonly present as a diffuse process and not a solid tumor. This is reported to occur in 4% to 5% of cases and has a metastatic risk of 24% at 5 years. According to Shields et al., the risk of metastasis is higher in a lesion with a large basal diameter and poorly defined margins.57 Such lesions are misdiagnosed about half of the time.

FIG. 279. B-scan of choroidal melanoma (small arrows) adjacent to optic nerve (large arrow)

TY is a 25-year-old man who was noted on routine examination to have a dark choroidal lesion with poorly defined margins. Echography revealed low reflective choroidal thickening in the area of the lesion on A-scan and an irregular surface on B-scan (Fig. 280). The differential diagnosis included an infiltrative process either by inflammatory or neoplastic cells. A systemic workup for malignancy was negative. He returned for follow-up in 3 months and the lesion had increased in size. Because of the high probability of diffuse melanoma, the eye was enucleated and pathology confirmed the diagnosis of epitheloid melanoma.

The low-to-medium and regular internal reflectivity of melanomas as imaged by the A-scan is the result of a dense, homogenous cell population with relatively few tissue interfaces to reflect the sound waves. On the other hand, choroidal nevi

have a less dense population of melanocytes that are loosely interspersed within the normal choroid. This results in multiple interfaces from which the sound beam is reflected resulting in higher reflectivity than is seen in melanomas on the A-scan (Fig. 281).

Another pigmented choroidal tumor with high internal reflectivity on A-scan is the melanocytoma (Fig. 282). This lesion is generally dome shaped on B-scan, but a case of a “mushrooming” melanocytoma has been reported.58 These lesions most often originate from pigmented cells within the optic disc, although they can occur anywhere in the uveal tract. They generally are heavily pigmented, with a jet-black appearance with a feathered edge that extends into the adjacent retina. Their clinical appearance allows an accurate diagnosis in most cases. Their malignant potential is very low, but there have been reports of transformation to a melanoma. They do not replace the choroid with a dense homogenous population of cells as the case

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FIG. 282. A-scan of melanocytoma (arrows)

with melanomas, but infiltrate the choroidal tissue in a less compact distribution.

An analogous situation on the cellular level occurs as metastatic tumors invade the choroid. These lesions invade the uveal tract in a sporadic pattern with areas of dense tumor cells and “fingers” of partial choroidal infiltration by the malignant cells. A-scan performed on these tumors will be irregular, with low spikes corresponding to the more homogenous areas of malignant infiltration and higher spikes corresponding to the more heterogeneous areas (Fig. 283). The lower reflective and regular areas can be confused with a choroidal melanoma if only that part of the lesion is imaged. The entire tumor must be scanned with particular attention to more irregular portions. The overall echographic picture of metastatic tumors usually includes irregular internal reflectivity with high and low echo spikes on A-scan.

Case Study 156. Diffuse Choroidal Melanoma

FIG. 283. A-scan of metastatic tumor to the choroid (arrows)

An important differential point is the rarity of echographically detectable spontaneous vascularity in metastatic tumors. These lesions are relatively flat compared to choroidal melanomas, which causes difficulty in visualizing the rapidly moving vertical spikes on A-scan. In addition, these tumors often lack the larger arterioles that are seen in melanomas. The examiner must carefully analyze the ultrasound screen for the rapid flickering movements visible on standardized A-scan and many B-scan units. It is helpful to enlarge the image with the zoom control and to look at the screen at a distance of a few inches. The degree of vascularity can be graded on a scale of 1 to 4+. The higher degrees of spontaneous movement are generally seen in larger melanomas. Their absence in a choroidal tumor over 3 mm in thickness should bring the diagnosis of melanoma into question.

HA is a 57-year-old woman with a history of breast cancer 5 years prior to her presentation. The tumor was first detected as a small nodule and was resected via a lumpectomy. She received a short course of chemotherapy and no radiation. She had been followed with annual exams by her oncologist and no evidence of recurrence or systemic spread of the tumor was noted.

She saw her ophthalmologist complaining of some distortion in vision in the right eye for the previous 3 weeks. His examination documented vision 20/30-2 OD and 20/20 OS. A paramacular yelloworange lesion was noted and she was referred for echography. B-scan revealed a dome-shaped high reflective lesion near the macula. A-scan demonstrated a thickness of 2.17 mm and medium-to-high reflectivity (Fig. 284). Spontaneous vascularity was not observed. The differential diagnosis first included metastatic tumor, but a subretinal disciform lesion could not be ruled out. Fluorescein angiography did not demonstrate choroidal new vessels. Her primary ophthalmologist informed the patient that there was a possibility that she had a metastatic breast lesion in her eye. Echography was repeated in a month and no change in the size or internal structure of the lesion was noted. This fact was more consistent with a neoplasm than subretinal blood.

Since her initial diagnosis of breast cancer, the patient had been actively participating in healthy lifestyle choices, including good nutrition with an emphasis on antioxidants, exercise, and stress reduction. She was involved in the American Cancer Society and ran a support group for cancer survivors. She had a very difficult time accepting the diagnosis of metastatic disease. She sought

other opinions nationally and was seen by several prominent ocular oncologists.

She finally underwent a fine needle biopsy of the ocular lesion that substantiated the diagnosis of metastatic breast cancer. A systemic workup had failed to reveal any other lesions so she underwent

FIG. 284. Top: A-scan of choroidal metastatic tumor (arrows). Bottom: B-scan of tumor (arrow)

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chemotherapy and focal radiation treatment to the choroidal lesion with a partial loss of central vision. There was no evidence of recurrent metastatic lesions to the eye or elsewhere over a 2-year follow-up.

Metastatic lesions to the globe and orbit commonly occur in systemically ill cancer patients with a known primary tumor that has already metastasized elsewhere in the body. They are often undetected in this location because such patients are usually preoccupied with the cancer treatment and its side effects and do not seek ophthalmologic care unless there are significant problems with vision. They frequently die from the cancer before the ocular metastasis is diagnosed. Several studies of autopsy series of patients who succumbed to metastatic cancer of various types found a 4% to 8% incidence of metastatic lesions in the eye and orbit.59 Most of these had been undiagnosed while the patients were alive. It was concluded that metastatic tumors to the globe and orbit are the most common malignancies that invade these structures. The rich vascular supply of the choroid predisposes it to invasion by metastatic cells. According to Madhavi and Finger,60 this tissue has a metastatic efficiency index that is the highest for any site in the body that has been investigated.

Case Study 157. Metastasis to Choroid

According to Shields et al., the most common metastatic tumors to the choroid are breast carcinomas in women.61 These lesions are bilateral in about 33% of cases and tend to be multifocal. They are relatively flat on the average, measuring about 2 mm. The next most common cancers that invade the eye are from the lung and are more often found in men. These tumors not infrequently present in the eye before the primary in the lung is diagnosed. Other less common primary cancers that metastasize to the eye are from the gastrointestinal tract, kidney, thyroid gland, and skin. Shields found no primary site in 51% of the cases in his series.

The diagnostic accuracy of metastatic tumors to the choroid by echography is less than that of malignant melanoma. This is mainly due to the relative lack of thickness when these lesions are first detected because internal structure cannot be adequately analyzed in a lesion in the range of 2 mm or less. Usually only a differential diagnosis can be given by the echographer, with a specificity of about 80%. In fact, some metastatic tumors will behave like melanomas by aggressively invading the choroid with a densely homogenous cell population. Such lesions can be misdiagnosed on A-scan. Examples include metastatic lung carcinomas, testicular carcinomas, and carcinoid tumors.

TS is a 56-year-old man with a long history of smoking. His medical history was positive for mild hypertension and borderline cholesterol. He presented to his optometrist with complaints of a shadow in the nasal field of vision in his right eye. His visual acuity measured 20/20 in both eyes and the external segment examination was normal. Fundus examination found a cream colored, dome-shaped lesion near the temporal equator. He was referred for fluorescein angiography, which revealed an area of choroidal hypofluorescence in the area of the lesion with adjacent pinpoint hyper-

by 9.83 mm by 7.6 mm in basal dimensions was detected. A-scan revealed medium and regular internal reflectivity without evidence of spontaneous vascularity (Fig. 285). The differential diagnosis first included choroidal melanoma. His primary care physician performed a systemic evaluation and a chest x-ray detected a suspicious nodule in the apex of the left upper lobe of the lung. Bronchoscopy was performed and biopsy of an apical lesion was determined to be poorly differentiated lung carcinoma. He was treated with a lobectomy of the left upper lobe and followed-up by his ophthalmologist several months later. A second choroidal lesion was detected in the right eye supernasally. This strongly supported the diagnosis of metastatic lung carcinoma in spite of the initial echographic findings.

The most common entities in the differential diagnosis of metastatic choroidal tumors are subretinal disciform lesions and choroidal hemangiomas. Fluorescein angiography is essential in the

diagnosis of active subretinal neovascularization (Fig. 286), but is less secure in burned out disciform lesions with gliotic scarring. Echography in such lesions usually demonstrates one or more

FIG. 285. Top: A-scan of metastatic tumor to the choroid (arrows) simulating a choroidal melanoma. Bottom: B-scan of the tumor (arrow)

WA is a 72-year-old man who presented with the complaint of a rapid decrease in vision of his left eye. Examination found visual acuity of 20/30−2 OD and 20/80+1 OS. Fundus examination of the right eye showed only mild macular pigmentary changes. The left macula was seen to have a bulging dark lesion with adjacent subretinal

hemorrhage. A neoplasm could not be ruled out. Fluorescein angiography showed mostly hypofluorescence throughout the macular area.

B-scan revealed a dome-shaped lesion with moderate spontaneous internal vascularity. A-scan demonstrated thickness of 4.9 mm and regular internal reflectivity (Fig. 287). The pattern was suspicious for subretinal hemorrhage, but a malignant lesion could not be ruled out. The patient was asked to return for repeat ultrasound in 3 weeks. On the return visit, A-scan measured the thickness at 1.50 mm with a high internal spike (Fig. 288). This was interpreted as a resolving subretinal hemorrhage with formation of a disciform scar.

Disciform lesions are easier to diagnose when they are submacular than when they are more peripheral. Age-related macular degeneration is the most frequent cause of irreversible visual loss in the elderly. Statistically it is much more likely

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that a macular lesion in this age group is due to subretinal neovascularization than to a metastatic lesion or melanoma. However, peripheral disciform lesions are much less common than the submacular process, which makes the distinction less certain in this location. Fluorescein angiography is helpful if active subretinal neovascularization with leakage of vessels is present.

Case Study 159. Subretinal Hemorrhage

The echographic findings can be equivocal, which necessitates follow-up ultrasound in a few weeks to see if the lesion is increasing or decreasing in size. A subretinal hemorrhage will generally partially resolve with a reduction in thickness. A-scan will often concurrently demonstrate increased irregularity of the internal structure. If such changes do not occur, then a tumor should be suspected.