Ординатура / Офтальмология / Английские материалы / Essentials in Ophthalmology Pediatric Ophthalmology Neuro-Ophthalmology Genetics_Lorenz, Moore_2006

Fig. 8.18. Choroidal osteoma surrounding the optic disc

more common in females. It consists of a plaque of mature bone that generally occurs adjacent to the optic disc (Fig. 8.18). It generally shows slow enlargement and choroidal neovascularization with subretinal hemorrhage as a frequent complication. The pathogenesis is unknown. Serum calcium and phosphorus levels are normal.

8.4.10 Uveal Nevus

Uveal nevus is a flat or minimally elevated, variably pigmented tumor that may occur in the iris (Fig. 8.19) or in the choroid (Fig. 8.20).Although it is most likely congenital, it is usually asymptomatic and not usually recognized until later in life. Although most uveal nevi are stationary and nonprogressive, malignant transformation into melanoma can occur in rare instances [14].

An important variant of iris nevus is the presence of bilateral multiple, slightly elevated melanocytic lesions of the iris, known as Lisch nodules. These lesions become clinically apparent at about age 5 years and are often the first sign of von Recklinghausen’s neurofibromatosis.

a

b

Fig. 8.19 a, b. Iris freckles and nevi. a Flat iris freckles on iris surface. b Slightly thickened iris nevus distorting the iris stroma and causing corectopia

8.4.11

Uveal Melanoma

Although uveal melanoma is generally a disease of adulthood, it is occasionally diagnosed in children [15]. It is a variably pigmented elevated mass that shows slow progression (Fig. 8.21). If it is not treated early, it has a tendency to metastasize to liver, lung, and other distant sites. Most advanced tumors are treated by enucleation. Radiotherapy of local tumor resection can be employed for less advanced tumors.

a

b

Fig. 8.20 a, b. Choroidal freckles and nevi. a Flat macular choroidal freckle. b Slightly thickened suspicious choroidal nevus in macular region

Fig. 8.21. Choroidal melanoma with shallow subretinal fluid and documented growth in a 16-year-old boy

a

b

Fig. 8.22 a, b. Congenital hypertrophy of the retinal pigment epithelium (RPE). a Solitary type with lacunae and halo. b Multifocal type

8.4.12

Congenital Hypertrophy

of Retinal Pigment Epithelium

Congenital hypertrophy of the retinal pigment epithelium (CHRPE) is a well circumscribed,flat, pigmented tumor that can occur anywhere in the fundus [16]. It often shows depigmented lacunae within the lesion and a surrounding pale halo. It can occur as a solitary lesion or it can be multiple as part of congenital grouped pigmentation lesion (Fig. 8.22). Similar but distinct multifocal pigmented lesions may be a marker for familial adenomatous polyposis and Gardner’s syndrome

in which patients have a high likelihood of developing colonic cancer [42].

8.4.13 Leukemia

Childhood leukemias can occasionally exhibit tumor infiltration in the retina, optic disc, and uveal tract.It is characterized by a swollen optic disc and thickening of the retina and choroid, often with hemorrhage and secondary retinal detachment. Intraocular leukemic infiltrates are generally responsive to irradiation and chemotherapy, but they generally portend a poor systemic prognosis.

Summary for the Clinician

∑Retinoblastoma is a highly malignant intraocular tumor of childhood

∑Most children with unilateral retinoblastoma have the eye enucleated

∑Most children with bilateral retinoblastoma are treated with chemoreduction and thermotherapy

∑All children with retinoblastoma should have genetic analysis to establish the presence and site of the 13Q mutation

∑Benign intraocular tumors of childhood are many and include choroidal nevus, congenital hypertrophy of the RPE, capillary hemangioma of the retina, and others

∑Young children with retinal capillary hemangioma should be evaluated for von Hippel Lindau syndrome

8.5

Orbital Tumors

A variety of orbital neoplasms and related space-occupying lesions can affect the orbit [43]. Orbital cellulitis secondary to sinusitis and inflammatory pseudotumors are more common than true neoplasms. Only about 5% of orbital lesions that come to biopsy prove to be malignant [44]. Cystic lesions are the most common group and vascular lesions are the second most common. This section covers orbital tumors and cysts but does not discuss orbital inflammatory or infectious conditions.

a

b

Fig. 8.23 a, b. Dermoid cyst near the lateral orbital rim, barely visible clinically. a Slight elevation of lateral orbital skin is shown. b Coronal CT showing the cystic mass

8.5.1 Dermoid Cyst

Dermoid cyst is the most common noninflammatory space occupying orbital mass in children [11, 45]. It usually appears in the first decade of life as a fairly firm, fixed, subcutaneous mass at the superotemporal orbital rim near the zygomaticofrontal suture (Fig. 8.23). Occasionally, a dermoid cyst may occur deeper in the orbit unattached to bone. Although it sometimes stationary,it does have a tendency to slowly enlarge. It can occasionally rupture, inciting an intense inflammatory reaction. Management is either serial observation or surgical removal of the mass.

8.5.4 Lymphangioma

Lymphangioma is an important vascular tumor of the orbit in children [4, 28, 50]. It tends to become clinically apparent during the first decade of life. It may case abrupt proptosis following orbital trauma, secondary to hemorrhage into the lymphatic channels within the lesion (Fig. 8.24). Such spontaneous hemorrhages, called chocolate cysts, may require aspiration or surgical evacuation to prevent visual loss from compression of the eye.

c

Fig. 8.24 a–c. Orbital lymphangioma producing rapid proptosis in a young child. a Downward displacement of the globe is shown. b Axial MRI showing bright signal in the blood filled cyst. c Coronal MRI showing the mass displacing the globe

8.5.5

Juvenile Pilocytic Astrocytoma

Juvenile pilocytic astrocytoma (optic nerve glioma) is the most common orbital neural tumor of childhood [28]. It is a cytological benign hamartoma that is generally stationary or very

Fig. 8.25. Juvenile pilocytic astrocytoma of optic nerve causing proptosis

slowly progressive. The affected child develops ipsilateral visual loss and slowly progressive axial proptosis (Fig. 8.25). Orbital imaging studies show an elongated or oval shaped mass that is well circumscribed because of the overlying dura mater. There is a greater incidence of this tumor in patients with neurofibromatosis. Since surgical excision necessitates blindness,the best management is periodic observation and surgical removal if there is blindness and cosmetically unacceptable proptosis. In cases that extend to the optic chiasm and are surgically unresectable, radiotherapy may be necessary.

8.5.6 Rhabdomyosarcoma

Rhabdomyosarcoma is the most important primary orbital malignant tumor of childhood [17, 28,46]. It usually occurs in the first decade of life with a mean age of 8 years at the time of diagnosis. It causes fairly rapid proptosis and displacement of the globe, usually without pain or major inflammatory signs (Fig. 8.26). Imaging studies show an irregular but fairly well-cir- cumscribed mass usually in the extraconal anterior orbit. Although orbital exenteration was

b

Fig. 8.26 a, b. Orbital rhabdomyosarcoma.a Proptosis and tumor involving the inferior fornix is shown. b Axial CT showing mass in medial orbit

often employed in the past, more recent experience has suggested that the best cure is obtained by performing a biopsy to confirm the diagnosis and treating with combined irradiation and chemotherapy, using vincristine, Cytoxan and adriamycin [17, 46].

8.5.7

Granulocytic Sarcoma (Chloroma)

Granulocytic sarcoma is the soft tissue infiltration by myelogenous leukemia [3, 28, 47]. Although leukemia usually appears first in the blood and bone marrow, the orbit soft tissues may be the initial site to become clinically apparent. The child presents with a fairly rapid onset of proptosis and displacement of the globe. Confirmation of the orbital lesion can be made by biopsy and the condition treated by chemotherapy or low-dose irradiation.

8.5.8 Lymphoma

The only important lymphoma to affect the orbit of children is Burkitt’s lymphoma.Although this tumor was originally recognized exclusively in African tribes, it is being recognized more often in patients with the autoimmune deficiency syndrome (AIDS) and as an American form in otherwise normal children [28].

8.5.9

Langerhans Cell Histiocytosis

Eosinophilic granuloma can affect the orbital bones as an intraosseous bone-destructive inflammatory lesion. Although it can occur anywhere in the orbit, it most often occurs in the anterior portion of the frontal and zygomatic bones. Recent ultrastructural studies have suggested the stem cell in eosinophilic granuloma and certain other tumors in the histiocytic X group is the Langerhans cell. Hence, the term Langerhans cell histiocytosis is becoming preferable [28].

8.5.10

Metastatic Neuroblastoma

Although orbital metastasis in children can occur secondary to Wilms’ and Ewing’s tumors, metastatic neuroblastoma is the most common metastatic orbital of childhood [28]. The majority of children with orbital metastasis of neuroblastoma have a previously diagnosed primary neoplasm in the adrenal gland. However, the orbital metastasis can be diagnosed before the adrenal primary in about 3% of cases.

Summary for the Clinician

∑Only 5% of orbital tumors in children are malignant

∑Dermoid cyst is the most common orbital mass in children

∑Orbital malignancies in children include rhabdomyosarcoma, lymphoma, leukemic infiltrates, and many others

∑Using accepted chemotherapy protocols, often with nearly 1 year of chemotherapy and a course of radiotherapy, children with orbital rhabdomyosarcoma generally have a favorable life prognosis

Acknowledgements. Supported by the Eye Tumor Research Foundation, Inc., Philadelphia, PA.

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|Core Messages

∑Electrophysiological testing provides an objective and noninvasive method for visual pathway evaluation

∑Complementary use of different electrophysiological procedures allows accurate characterisation and localisation of dysfunction. EOG: The photoreceptor/RPE interface; ERG: rod and cone photoreceptor and inner retinal function; PERG: macular and retinal ganglion cell function; VEP: intracranial visual pathway function

∑Electrophysiology enables distinction between disorders that may present with similar signs and/or symptoms and facilitates differentiation between benign and severe, progressive and stationary disorders

∑Invaluable in suspected nonorganic visual loss

∑Accurate electrophysiological phenotyping is likely to become increasingly important as genotyping increases and new therapies are developed

9.1 Introduction

The electrophysiological examination of the paediatric patient can be of great clinical importance. In addition to the objective nature of the data provided by electrophysiological testing, the potential inability of a child to describe accurately, if at all, their symptoms places electrophysiology in a privileged position of diagnostic importance. Further, it is noninvasive.

A formal clinical audit of the role of electrophysiology in paediatric practice demonstrated a significant influence on management [88]. After an initial description of the available techniques and their uses, the subsequent discussion will adopt a practical approach to diagnosis, based on presenting signs and symptoms, to demonstrate how electrophysiological testing can enable management decisions to be taken with greater confidence.

9.2

Electrophysiological Techniques

9.2.1 Electroretinography

The electroretinogram (ERG) is the mass response of the retina to a luminance stimulus, usually a stroboscopically generated shortduration flash (Fig. 9.1). In adults, ERGs are recorded using corneal electrodes with stimuli delivered via a Ganzfeld bowl. This approach is tenable with older children who are capable of understanding the demands of testing, but there are two distinct schools of thought in relation to the young child or infant. Some adopt the approach that children are simply young adults, and use the same techniques; inevitably this requires either restraint or sedation in some patients. Others adopt the view that the clinical data required in a young child are different to those in an adult population, requiring answers to different, less complex questions, such as “is this baby blind” or “why has this child got nystagmus”, and that clinically meaningful and satisfactory data can be obtained using less inva-