Ординатура / Офтальмология / Английские материалы / Clinical Ophthalmic Echography_Harrie_2008

RC is a 2-year-old girl with a history of a vascular lesion involving the left upper lid and anterior orbit. It was diagnosed as a capillary hemangioma and intralesional injection of steroids was recommended to the parents because the tumor was enlarging rapidly and threatening to obstruct the visual axis. The child was referred for echography to substantiate the diagnosis and direct the steroid injection.

Echography by A-scan showed a 17-mm lesion with irregular internal reflectivity and marked vascularity on examination with an obstetrical Doppler unit. A low reflective area with marked spontaneous vascularity was noted (Fig. 253) and a marking pen was used to outline this highly vascular area. A triamcinolone injection of 1 cc was performed with avoidance of the area with the highest blood flow to reduce the possibility of retrograde injection of steroid into the retinal arterial vasculature. The injection was accomplished without difficulty

FIG. 253. A-scan of low reflective high flow area (middle arrow) in infantile hemangioma (small vertical arrows)

and the lesion regressed significantly over the next several weeks.

Varices can occur in the orbit but sometimes present as more visible lesions in the paraocular area.

RG is a 25-year-old man who presented with the history of bulging of his right eye when he felt increased pressure in his head when lifting weights or bending over and picking up heavy objects. Examination found vision in both eyes of 20/20 and normal intraocular pressures. Proptosis of his right eye was measured at 23 mm when he performed a valsalva maneuver and his left eye exophthalmometry measurement was normal at 18 mm.

Echography showed a normal right orbit before valsalva and a low reflective encapsulated lesion in

the mid-orbit after he increased venous pressure by bending over and bearing down (Fig. 255).

The most common marginal lid lesion encountered in clinical practice is the chalazion (stye). This often starts as a focal tender bump at the lid margin that may come to a head and involute spontaneously or with the application of warm compresses. However, it may evolve into a more chronic form called a chalazion. Generally, echography has little or no role in these lesions except in atypical presentations.

CT is a 35-year-old man with a reddish focal swelling in his right lower lid that fluctuated in size over several months. He was seen by his primary care doctor and diagnosed with a chalazion. He had tried hot packs, oral antibiotics, and was seen by an ophthalmologist who injected steroids into the lesion, but it persisted.

Echography was performed and showed a 1-cm encapsulated lesion with medium internal reflectivity on A-scan (Fig. 256). The differential diagnosis included an inflammatory infiltrate but a lymphoid lesion could not be ruled out. Because of this possibility and the persistence of the tumor, a biopsy was performed.

The pathological diagnosis was a B-cell lymphoma and a systemic workup was initiated with no evidence of lymphoma at other sites. Nevertheless, the patient was informed that the probability of a distant focus of lymphoma was 60% to 70% because of the involvement of the ocular adenexae.

Bulges in the nasal canthus are often related to pathology of the nasolacrimal system. Obstruction of the nasolacrimal duct is quite common in newborns and is generally a self-correcting problem but can be treated by probing. Rarely, an infant is born with a tense cystic bulge in the area of the nasolacrimal fossa. This is called a dacriocystocele or lacrimal sac mucocele. It may be of the regurgitating type when mucous and fluid can be expressed

FIG. 256. A-scan of atypical chalazion (vertical arrows)

through the punctum when the examiner presses on the sac. If secretions cannot be expressed due to obstruction or kinking of the common canaliculus, then it is of the nonregurgitating type and can result in marked distention of the lacrimal sac.

Echography is useful in such cases by demonstrating a well-outlined and low reflective structure without vascularity. The A-scan can be placed inside the nose. If the mucocele descends into the nasal cavity it is best treated by a myringotomy blade from the nasal end because it may not respond to probing of the system performed through the punctum.

TE is a 3-day-old infant who was noted to have a moderately firm swelling in the corner of the left eye. This increased over the next 2 days so the parents sought ophthalmic consultation. The doctor was relatively certain the lesion was a lacrimal sac mucocele. The differential diagnosis included a meningoencephalocele, but the lack of pulsations made this unlikely.

Echography demonstrated a well-outlined echolucent lesion on B-scan with regular low reflectivity on A-scan. The A-scan probe was placed inside the nose and a high reflective membrane was encountered that was consistent with a mucocele of the sac (Fig. 257). An otolaryngologist performed an incision with a myringotomy blade and under the same anesthesia an ophthalmologist performed nasolacrimal probing. Mucinous fluid gushed out and the distended lacrimal sac was decompressed.

Rarely, tumors can originate from the lacrimal sac. When a patient presents with the complaint

FIG. 257. A-scan inside nose of dacriocystocele (vertical arrows)

of tearing, the sac on the involved side should be palpated. Bloody tears are especially suggestive of a neoplasm. Firmness may indicate dacrioliths in the sac that may require surgical removal, but also may indicate a neoplasm.

JR is a 34-year-old man who presented with complaints of epiphora on the left side for several months. He had been given antibiotics and decongestant nasal sprays by his primary care physician without relief of the tearing. He was referred to an ophthalmologist, who noted some fullness in the nasolacrimal fossa and found a firm lesion on palpation.

Echography revealed a moderately echodense encapsulated lesion on B-scan and a regular medium reflective growth with moderate spontaneous vascularity on A-scan (Fig. 258). CT scan showed an isodense process in the lacrimal sac without bone destruction or invasion. The patient was referred for a dacriocystorhinostomy with the plan to perform a

concurrent excisional biopsy of the lesion. A reddish firm tumor was found at surgery.

Pathology demonstrated a cellular lesion with vascular elements consistent with a hemangiopericytoma of the lacrimal sac. The patient was followed serially with ultrasound to eliminate recurrence of the tumor.

Other tumors can also rarely involve the lacrimal sac and include epithelial tumors, such as squamous cell carcinoma, adenocarcinoma, and oncocytoma. Nonepithelial tumors, such as rhabdomyosarcoma, lymphoma, plasmocytoma, and leukemia can also be found.

Epiphora can be the first sign of an extensive process invading the medial orbital bony wall and may even extend intracranially.

FIG. 259. A-scan of meningioma invading lacrimal sac (first two vertical arrows) and paranasal sinuses (between second and third arrows)

FIG. 260. Computed tomography of meningioma invading nasal orbit (arrow)

oma (Fig. 260). This diagnosis was confirmed on biopsy.

Occasionally, a foreign body that strikes the periocular area will lodge in the eyelids. Any history of high-speed projectiles hitting the eye or adnexae, especially without safety goggles being worn, should prompt a careful examination for a tiny self-sealing entry wound in the lids or globe. The threat to the eye is greatly increased by the entry of a foreign body into the ocular contents.

CP is a 23-year-old man who was involved in a motor vehicle accident with shattered glass from the windshield striking his eye. He went to an emergency room where the doctor “picked out many pieces of glass from the eye.” He later felt focal tenderness in the lid and was convinced that he could palpate a small firm object under the eyelid skin. He was seen by an ophthalmologist who was not able to palpate any foreign object in the lid. The patient demanded that some sort of “x-ray” be performed to find the object. The doctor felt radiographic studies including CT would not show a piece of glass so the patient was referred for echography.

Standard contact B-scan did not show any foreign body signals in the globe or anterior orbital tissue but the image of the eyelid was hidden in the probe’s 5-mm dead zone. An immersion scan with a 20 MHz probe was performed utilizing a soft silicone immersion shell filled with methylcellulose to back the probe away from the lid to display its full thickness (Fig. 261). No foreign body signal was detected and the patient was reassured that there was nothing to worry about.

The differential diagnosis of proptosis and other malpositions of the eye is a long one. Echography

provides a rapid and inexpensive method to quickly diagnose many of these entities in an office setting. The quantitative ability of the A-scan can provide a focused differential diagnosis in most cases and can correctly characterize the lesion in many cases.

FIG. 261. Immersion scan of normal eyelid (arrows)

Echography is extremely valuable in the evaluation of lumps and bumps in and around the eye. It is the most valuable of the various imaging techniques in the evaluation of intraocular lesions. The approach to intraocular tumors has changed dramatically in the last 25 years. Prior to that time, eyes were often enucleated because of the suspicion of intraocular melanoma. Ferry published a major intraocular tumor pathology study from the Armed Forces Institute of Pathology (AFIP) in the 1960s and found that 20% of eyes enucleated with the diagnosis of malignant melanoma harbored other mostly nonmalignant lesions. This study was criticized because it was performed before indirect ophthalmoscopy and fluorescein angiography were widely used in the evaluation of intraocular tumors. Ferry repeated the study in the 1970s when these modalities were part of routine practice and the same 20% misdiagnosis rate was found.48

The list of lesions misdiagnosed as choroidal melanomas with their incidence in the pathology series includes:

Many of these lesions can be readily diagnosed by careful ophthalmoscopy but this becomes more difficult as a direct function of the opacity of the ocular media. Such obscurations to the passage of the light from the ophthalmoscope are not inhibitory to the sound beam of the echographer. This modality is essential in the accurate characterization of a number of intraocular lesions. The most difficult clinical differentiation is among solid tumors of the fundus, such as metastatic tumors, hemangiomas, and large nevi, even when they are not obscured by media opacification. A-scan allows tissue differentiation that is especially valuable in separating choroidal melanomas from the various mimickers.

Since the second AFIP study, echography has dramatically impacted the accuracy of the evaluation of intraocular tumors. This technique began to be used more extensively in the 1980s and the rate of specificity for the diagnosis of choroidal melanoma increased significantly. The latest data from the Collaborative Ocular Melanoma Study (COMS) documents a diagnostic accuracy of 99.7%, although atypical lesions were not included.49 Standardized echography was the primary ancillary tool used in this study. Ultrasound has become the standard in detecting and diagnosing intraocular tumors. According to Trubo, “the gold standard in evaluating ocular tumors remains ocular ultrasound, including both A- and B-scan ultrasound.” He quotes Timothy Murray who states, “it is clearly better than the best MRI scan, the best CT scan or the best PET scan that we have.”50 This level of reliability approaches that of microscopic tissue sections as studied by the pathologist. Echography is unable to differentiate

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cell types, but the tissue architecture created by collections of cells has a direct correlation to the reflectivity patterns on A-scan. This is especially important in an organ, such as the eye, in which biopsy may be hazardous.

Current radiologic techniques, such as magnetic resonance imaging (MRI) and computed tomography (CT) rely mostly on gross morphology and are not able to differentiate tissue at the resolution of ultrasound. Positron emission tomography (PET)/CT technology does its imaging in the biochemical realm. It displays the concentration of radioactively tagged glucose and other molecules as they are metabolized in different tissues. Finger et al. reviewed two cases of intraocular melanoma in which the first evidence of liver metastases was focal hot spots on PET/CT scanning.51 This finding was noted before liver function tests became abnormal. However, this technology is not widely available and is relatively expensive. The usefulness of PET scans for the characterization intraocular tumors has not been established.

B-scan echography is similar to MRI and CT scanning as it provides valuable morphologic information about the size and shape of ocular and orbital lesions. Lesions such as ocular melanomas often have an almost pathognomonic mushroom shape on B-scan (Fig. 262). This shape is due to the constriction of the “neck” of the tumor as it erodes and breaks through Bruch’s membrane into the subretinal space.

Part VI. Lumps and Bumps

Rarely, a rapidly growing metastatic tumor breaks through Bruch’s membrane. B-scan also allows an overview of the local surround of a lesion. It can demonstrate subretinal fluid and the extent of any retinal detachment (Fig. 263). It provides a picture of tumor proximity to the optic nerve, which is an important prognostic factor (Fig. 264). B-scan is essential in measuring the basal dimensions of a lesion, which enables the calculation of total tumor volume when combined with the very precise thickness measurements attainable by A-scan.

The use of A-scan enables a peek inside the tissue being studied. Histological characteristics are directly correlated to the characteristics of the spikes. The major A-scan criteria for the diagno-

FIG. 262. B-scan of choroidal melanoma with mushrooming shape (arrow)

FIG. 263. Top: A-scan of subretinal fluid (first two arrows) over choroidal melanoma (second and third arrows). Bottom: B-scan of subretinal fluid (vertical arrow) over melanoma (horizontal arrow)