Diktyoma

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Diktyoma
Medulloepithelioma Histology.jpg
Histopathology of medulloepithelioma showing characteristic neural tube like strands.

Diktyoma, or ciliary body medulloepithelioma, or teratoneuroma, is a rare tumor arising from primitive medullary epithelium in the ciliary body of the eye. Almost all diktyomas arise in the ciliary body, although, rarely, they may arise from the optic nerve head or retina. [1]

Medulloepithelioma Human disease

Medulloepithelioma is a rare, primitive, fast-growing brain tumour thought to stem from cells of the embryonic medullary cavity. Tumours originating in the ciliary body of the eye are referred to as embryonal medulloepitheliomas, or diktyomas.

Ciliary body part of an eye

The ciliary body is a part of the eye that includes the ciliary muscle, which controls the shape of the lens, and the ciliary epithelium, which produces the aqueous humor. The vitreous humor is produced in the non-pigmented portion of the ciliary body. The ciliary body is part of the uvea, the layer of tissue that delivers oxygen and nutrients to the eye tissues. The ciliary body joins the ora serrata of the choroid to the root of the iris.

Human eye mammalian eye; part of the visual organ of the human body, and move using a system of six muscles

The human eye is an organ that reacts to light and allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth. The human eye can differentiate between about 10 million colors and is possibly capable of detecting a single photon. The eye is part of the sensory nervous system.

Contents

The name "diktyoma" comes from its characteristic findings on histology.

Histology Study of the microscopic anatomy of cells and tissues of plants and animals

Histology, also known as microscopic anatomy or microanatomy, is the branch of biology which studies the microscopic anatomy of biological tissues. Histology is the microscopic counterpart to gross anatomy, which looks at larger structures visible without a microscope. Although one may divide microscopic anatomy into organology, the study of organs, histology, the study of tissues, and cytology, the study of cells, modern usage places these topics under the field of histology. In medicine, histopathology is the branch of histology that includes the microscopic identification and study of diseased tissue. In the field of paleontology, the term paleohistology refers to the histology of fossil organisms.

Signs and Symptoms

The most common symptoms of diktyoma are vision loss and pain, while the most common signs are leukocoria and presence of a mass in the iris or ciliary body. [1] [2] Other signs and symptoms include lens subluxation, glaucoma, cataract, exophthalmos, buphthalmos, strabismus, and ptosis.

Leukocoria abnormal white reflection from the retina of the eye

Leukocoria is an abnormal white reflection from the retina of the eye. Leukocoria resembles eyeshine, but leukocoria can occur in humans and other animals that lack eyeshine because their retina lacks a tapetum lucidum.

Iris (anatomy) part of an eye

In humans and most mammals and birds, the iris is a thin, circular structure in the eye, responsible for controlling the diameter and size of the pupil and thus the amount of light reaching the retina. Eye color is defined by that of the iris. In optical terms, the pupil is the eye's aperture, while the iris is the diaphragm.

Ectopia lentis disorder of lens

Ectopia lentis is a displacement or malposition of the eye's crystalline lens from its normal location. A partial dislocation of a lens is termed lens subluxation or subluxated lens; a complete dislocation of a lens is termed lens luxation or luxated lens.

Diagnosis

Classification

Diktyoma is classified into teratoid and nonteratoid types, based on heteroplastic tissue in the former. Each type may be sub-classified as benign or malignant based on histology. [3]

Benign tumor disease of cellular proliferation that results in abnormal growths in the body which lack the ability to metastasize

A benign tumor is a mass of cells (tumor) that lacks the ability to invade neighboring tissue or metastasize. However, they can sometimes be quite large. When removed, benign tumors usually do not grow back, whereas malignant tumors sometimes do. Unlike most benign tumors elsewhere in the body, benign brain tumors can be life threatening. Benign tumors generally have a slower growth rate than malignant tumors and the tumor cells are usually more differentiated. They are typically surrounded by an outer surface or remain with the epithelium. Common examples of benign tumors include moles and uterine fibroids.

Cancer group of diseases

Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal bleeding, prolonged cough, unexplained weight loss, and a change in bowel movements. While these symptoms may indicate cancer, they can also have other causes. Over 100 types of cancers affect humans.

Based on histology, the tumor is classified as malignant if it contains poorly differentiated neuroblasts, nuclear pleomorphism, markedly abnormal mitotic activity, sarcomatous components, or invasion into the uvea, cornea, or sclera. [1] Most diktyomas are malignant. [1] [4]

A neuroblast or primitive nerve cell is a postmitotic cell that does not divide further, and which will develop into a neuron after a migration phase. Neuroblasts differentiate from radial glial cells and are committed to becoming neurons. Neural stem cells, which only divide symmetrically to produce more neural stem cells, transition gradually into radial glial cells. Radial glial cells, also called radial glial progenitor cells, divide asymmetrically to produce a neuroblast and another radial glial cell that will re-enter the cell cycle.

Mitosis nuclear division cycle for eukaryotic cells in which the two resulting nuclei are genetically identical

In cell biology, mitosis is a part of the cell cycle when replicated chromosomes are separated into two new nuclei. Cell division gives rise to genetically identical cells in which the number of chromosomes is maintained. In general, mitosis is preceded by the S stage of interphase and is often accompanied or followed by cytokinesis, which divides the cytoplasm, organelles and cell membrane into two new cells containing roughly equal shares of these cellular components. Mitosis and cytokinesis together define the mitotic (M) phase of an animal cell cycle—the division of the mother cell into two daughter cells genetically identical to each other.

Sarcoma cell type cancer that has material basis in abnormally proliferating cells derived from embryonic mesoderm

A sarcoma is a cancer that arises from transformed cells of mesenchymal origin. Connective tissue is a broad term that includes bone, cartilage, fat, vascular, or hematopoietic tissues, and sarcomas can arise in any of these types of tissues. As a result, there are many subtypes of sarcoma, which are classified based on the specific tissue and type of cell from which the tumor originates. It is important to note that sarcomas are primary connective tissue tumors, meaning that they arise in connective tissues. This is in contrast to secondary connective tissue tumors, which occur when a cancer from elsewhere in the body spreads to the connective tissue. The word sarcoma is derived from the Greek σάρξ sarx meaning "flesh".

Imaging findings

Imaging studies such as ultrasonography (US), Computerized Tomography (CT) and Magnetic Resonance Imaging (MRI) may aid diagnosis. On ultrasound, diktyomas typically appear as echogenic, irregularly shaped to ovoid masses. [5] [6] Ultrasound is excellent for demonstrating cystic collections of vitreous fluid in the tumor, and may show calcifications in the teratoid type.

Medical diagnosis process to determine or identify a disease or disorder

Medical diagnosis is the process of determining which disease or condition explains a person's symptoms and signs. It is most often referred to as diagnosis with the medical context being implicit. The information required for diagnosis is typically collected from a history and physical examination of the person seeking medical care. Often, one or more diagnostic procedures, such as medical tests, are also done during the process. Sometimes posthumous diagnosis is considered a kind of medical diagnosis.

Dystrophic calcification

Dystrophic calcification (DC) is the calcification occurring in degenerated or necrotic tissue, as in hyalinized scars, degenerated foci in leiomyomas, and caseous nodules. This occurs as a reaction to tissue damage, including as a consequence of medical device implantation. Dystrophic calcification can occur even if the amount of calcium in the blood is not elevated. Basophilic calcium salt deposits aggregate, first in the mitochondria, and progressively throughout the cell. These calcifications are an indication of previous microscopic cell injury. It occurs in areas of cell necrosis in which activated phosphatases bind calcium ions to phospholipids in the membrane.

On CT, dityomas typically appear as dense, irregular masses in the ciliary body, which enhances with administration of intravenous contrast material. [7] CT is excellent for demonstrating dystrophic calcifications in the teratoid type. [4] [6]

On MRI, dityomas typically appear slightly to moderately hyperdense to vitreous on T1-weighted images and hypodense on T2-weighted images, with marked homogeneous enhancement (except for prominent parts of cystic components, which, if present, may impart heterogeneity) after administration of intravenous contrast material. [6] MRI is excellent for detection of tumors as small as 2 millimeters. [8]

Gross pathologic findings

Grossly, the tumor appears white, gray, or yellow, with irregular surface, often studded with small cysts. [3] More small cysts may be found on cut sections. These cysts may break off the surface and float freely in aqueous or vitreous humour. [4] [9] The tumor may also contain chalky grayish-white particles. The lens may be covered by a semi-translucent membrane in some case. [3] Tumor may invade locally to involve the iris or anterior retina, or through the cornea or sclera. In advanced cases, tumor may fill the entire globe, similar to retinoblastoma. [3]

Histologic findings

Microscopically, the tumor cells recapitulate embryonic sensory retina or nonpigmented ciliary epithelium. The chalky grayish-white particles within the tumor mass correspond to foci of cartilage on histology; the semi-translucent membrane covering the lens in some tumors corresponds to spreading neoplastic cells. [4] [6]

Tumor cells form a characteristic diktyomatous pattern, with folded cords and sheets resembling a fisherman's net. [3] In early development of the retina, the medullary epithelial cells acquire polarity, such that a basement membrane associated with the vitreous forms the internal limiting membrane on one side, while terminal bars form the outer limiting membrane on the other side. Proliferating tumor cells of diktyoma maintain the same polarity, arranged in cords and sheets folding back upon themselves. Depending on the direction of the folding, some folds surround fluid collection, while others do not. [1] These fluid-filled spaces correspond to the grossly observed small cysts, which are mainly composed of vitreous humor. [1]

About 30-50 percent of diktyomas contain heteroplastic elements, and thus belong to the teratoid subtype. [1] [4] These heteroplatic elements may include hyaline cartilage, rhabdomyoblasts, and neuroglial tissue. [3] Sarcomatous elements may be seen in malignant tumors. Foci of dystrophic calcifications may be present.

Treatment

Diktyoma is treated by either close observation, or enucleation of the eye. Surgical resection is no longer done due to risk of late complications and metastases. Small lesions can be treated with iodine-125 plaque brachytherapy. [10] Distant metastases and mortality are rare. Mortality may occur in patients with extraocular extension to the brain. [1] [4] [6] Lack of glial differentiation, as demonstrated by negative staining for glial fibrillary acidic protein (GFAP), may confer a favourable prognosis. [11]

Epidemiology

Mean age at diagnosis is 5 years. [1] [2] While most cases occur in young children, adult cases have been reported. [1] [9] Incidence is similar in male and female and among different races.

Related Research Articles

Cornea part of the eye

The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. The cornea, with the anterior chamber and lens, refracts light, with the cornea accounting for approximately two-thirds of the eye's total optical power. In humans, the refractive power of the cornea is approximately 43 dioptres. The cornea can be reshaped by surgical procedures such as LASIK.

Vitreous body

The vitreous body is the clear gel that fills the space between the lens and the retina of the eyeball of humans and other vertebrates. It is often referred to as the vitreous humor or simply "the vitreous".

Choroid vascular layer of the eye, containing connective tissue, and lying between the retina and the sclera

The choroid, also known as the choroidea or choroid coat, is the vascular layer of the eye, containing connective tissues, and lying between the retina and the sclera. The human choroid is thickest at the far extreme rear of the eye, while in the outlying areas it narrows to 0.1 mm. The choroid provides oxygen and nourishment to the outer layers of the retina. Along with the ciliary body and iris, the choroid forms the uveal tract.

Iris cyst

Iris cysts are hollow cavities in the eye filled with secretion. They come in various sizes, numbers, shapes, pigments and can be free-floating, attached to the pupillary margin or within the posterior chamber. Most frequently iris cysts don't cause any issues, but they can cause problems like: “fly biting” behavior, corneal endothelial pigment, lens capsular pigmentation, altered iris movement, decreased aqueous outflow with subsequent glaucoma or block the vision when grown to big. They can be acquired or innate. Possible causes are inflammation, drug-induced, uveitis, a trauma, tumor-induced, parasitic or implantation. Most frequently iris cysts are benign and need no treatment. Sometimes iris cysts are causing problems and need to be deflated. Iris cysts can be treated with trans corneal diode laser treatment, fine-needle aspiration or surgical excision. For the treatment of iris cysts is a conservative approach favored.

Asteroid hyalosis

Asteroid hyalosis is a degenerative condition of the eye involving small white opacities in the vitreous humor. It is known to occur in humans, dogs, cats, horses, and chinchillas. Clinically, these opacities are quite refractile, giving the appearance of stars shining in the night sky—except that ocular asteroids are often quite mobile. Ocular asteroids must be distinguished from the more common typical vitreous floaters, which are usually fibrillar or cellular condensates. The cause of asteroid hyalosis is unknown, but it has been associated with diabetes mellitus, hypertension, hypercholesterolemia, and, in certain animals, tumors of the ciliary body. In dogs, asteroid hyalosis is considered to be an age related change. The asteroid bodies are made up of hydroxylapatite, which in turn consists of calcium and phosphates or phospholipids. While asteroid hyalosis does not usually severely affect vision, the floating opacities can be quite annoying, and may interfere significantly with visualization and testing of the retina. While treatment of asteroid hyalosis is usually unnecessary, vitrectomy may occasionally be indicated, for both diagnostic and therapeutic purposes.

Coats disease Human disease

Coats' disease, is a rare congenital, nonhereditary eye disorder, causing full or partial blindness, characterized by abnormal development of blood vessels behind the retina. Coats' disease can also fall under glaucoma.

Aneurysmal bone cyst, abbreviated ABC, is an osteolytic bone neoplasm characterized by several sponge-like blood or serum filled, generally non-endothelialized spaces of various diameters.

Myoepithelial cells are cells usually found in glandular epithelium as a thin layer above the basement membrane but generally beneath the luminal cells. These may be positive for alpha smooth muscle actin and can contract and expel the secretions of exocrine glands. They are found in the sweat glands, mammary glands, lacrimal glands, and salivary glands. Myoepithelial cells in these cases constitute the basal cell layer of an epithelium that harbors the epithelial progenitor. In the case of wound healing, myoepithelial cells reactively proliferate. Presence of myoepithelial cells in a hyperplastic tissue proves the benignity of the gland and, when absent, indicates cancer. Only rare cancers like adenoid cystic carcinomas contains myoepithelial cells as one of the malignant component.

Eye neoplasm sensory system cancer located in the eye that is characterized by uncontrolled cellular proliferation in the eye

Eye neoplasms can affect all parts of the eye, and can be a benign tumor or a malignant tumor (cancer). Eye cancers can be primary or metastatic cancer. The two most common cancers that spread to the eye from another organ are breast cancer and lung cancer. Other less common sites of origin include the prostate, kidney, thyroid, skin, colon and blood or bone marrow.

The blood–ocular barrier is a barrier created by endothelium of capillaries of the retina and iris, ciliary epithelium and retinal pigment epithelium. It is a physical barrier between the local blood vessels and most parts of the eye itself, and stops many substances including drugs from traveling across it. Inflammation can break down this barrier allowing drugs and large molecules to penetrate into the eye. As the inflammation subsides, this barrier usually returns.

Optic disc drusen Human disease

Optic disc drusen (ODD) are globules of mucoproteins and mucopolysaccharides that progressively calcify in the optic disc. They are thought to be the remnants of the axonal transport system of degenerated retinal ganglion cells. ODD have also been referred to as congenitally elevated or anomalous discs, pseudopapilledema, pseudoneuritis, buried disc drusen, and disc hyaline bodies.

Epiretinal membrane disease of the eye in response to changes in the vitreous humor or more rarely, diabetes


Epiretinal membrane is a disease of the eye in response to changes in the vitreous humor or more rarely, diabetes. Sometimes, as a result of immune system response to protect the retina, cells converge in the macular area as the vitreous ages and pulls away in posterior vitreous detachment (PVD). PVD can create minor damage to the retina, stimulating exudate, inflammation, and leucocyte response. These cells can form a transparent layer gradually and, like all scar tissue, tighten to create tension on the retina which may bulge and pucker, or even cause swelling or macular edema. Often this results in distortions of vision that are clearly visible as bowing and blurring when looking at lines on chart paper within the macular area, or central 1.0 degree of visual arc. Usually it occurs in one eye first, and may cause binocular diplopia or double vision if the image from one eye is too different from the image of the other eye. The distortions can make objects look different in size, especially in the central portion of the visual field, creating a localized or field dependent aniseikonia that cannot be fully corrected optically with glasses. Partial correction often improves the binocular vision considerably though. In the young, these cells occasionally pull free and disintegrate on their own; but in the majority of sufferers the condition is permanent. The underlying photoreceptor cells, rod cells and cone cells, are usually not damaged unless the membrane becomes quite thick and hard; so usually there is no macular degeneration.

Optic pit Human disease

Optic pit, optic nerve pit, or optic disc pit is a congenital excavation of the optic disc, resulting from a malformation during development of the eye. Optic pits are important because they are associated with posterior vitreous detachments (PVD) and even serous retinal detachments.

Proliferative vitreoretinopathy (PVR) is a disease that develops as a complication of rhegmatogenous retinal detachment. PVR occurs in about 8–10% of patients undergoing primary retinal detachment surgery and prevents the successful surgical repair of rhegmatogenous retinal detachment. PVR can be treated with surgery to reattach the detached retina but the visual outcome of the surgery is very poor.

Sohan Singh Hayreh is an ophthalmologist, clinical scientist, and professor emeritus of ophthalmology at the University of Iowa. As one of the pioneers in the field of fluorescein angiography, he is generally acknowledge to be a leading authority in vascular diseases of the eye and the optic nerve. For over 60 years, Hayreh has been actively involved in basic, experimental, and clinical research in ophthalmology, publishing over 400 original peer-reviewed articles in various international ophthalmic journals, 6 classical monographs and books in his field of research, and more than 50 chapters in ophthalmic books. He has made many seminal observations dealing with the ocular circulation in health and disease, the optic disc and the optic nerve, retinal and choroidal vascular disorders, glaucomatous optic neuropathy, fundus changes in malignant arterial hypertension, ocular neovascularization, rheumatologic disorders of the eye, and nocturnal arterial hypotension. He is an elected fellow of the National Academy of Medical Sciences.

Odontogenic cyst are a group of jaw cysts that are formed from tissues involved in odontogenesis. Odontogenic cysts are closed sacs, and have a distinct membrane derived from rests of odontogenic epithelium. It may contain air, fluids, or semi-solid material. Intra-bony cysts are most common in the jaws, because the mandible and maxilla are the only bones with epithelial components. That odontogenic epithelium is critical in normal tooth development. However, epithelial rests may be the origin for the cyst lining later. Not all oral cysts are odontogenic cyst. For example, mucous cyst of the oral mucosa and nasolabial duct cyst are not of odontogenic origin.
In addition, there are several conditions with so-called (radiographic) 'pseudocystic appearance' in jaws; ranging from anatomic variants such as Stafne static bone cyst, to the aggressive aneurysmal bone cyst.

Orbital lymphoma Human disease

Orbital lymphoma is a common type of non-Hodgkin lymphoma that occurs near or on the eye. Common symptoms include decreased vision and uveitis. Orbital lymphoma can be diagnosed via a biopsy of the eye and is usually treated with radiotherapy or with combination with chemotherapy.

Vitreomacular adhesion Human medical condition

Vitreomacular adhesion (VMA) is a human medical condition where the vitreous gel of the human eye adheres to the retina in an abnormally strong manner. As the eye ages, it is common for the vitreous to separate from the retina. But if this separation is not complete, i.e. there is still an adhesion, this can create pulling forces on the retina that may result in subsequent loss or distortion of vision. The adhesion in of itself is not dangerous, but the resulting pathological vitreomacular traction (VMT) can cause severe ocular damage.

References

  1. 1 2 3 4 5 6 7 8 9 10 Broughton, Warren L.; Zimmerman, Lorenz E. (March 1978). "A Clinicopathologic Study of 56 Cases of Intraocular Medulloepitheliomas". American Journal of Ophthalmology. 85 (3): 407–418. doi:10.1016/S0002-9394(14)77739-6.
  2. 1 2 McLeanIW, Burnier MN, Zimmerman LE, Jakobiec FA. Tumors of the retina. In: Rosai J, Sobin LH, eds. Atlas of tumor pathology: tumors of the eye and ocular adnexa. Washington, DC: Armed Forces Institute of Pathology, 1994; 101–135.
  3. 1 2 3 4 5 6 Chung, Ellen M.; Specht, Charles S.; Schroeder, Jason W. (July 2007). "Pediatric Orbit Tumors and Tumorlike Lesions: Neuroepithelial Lesions of the Ocular Globe and Optic Nerve". RadioGraphics. 27 (4): 1159–1186. doi:10.1148/rg.274075014. PMID   17620473.
  4. 1 2 3 4 5 6 Shields, Jerry A.; Eagle, Ralph C.; Shields, Carol L.; De Potter, Patrick (December 1996). "Congenital Neoplasms of the Nonpigmented Ciliary Epithelium (medulloepithelioma)". Ophthalmology. 103 (12): 1998–2006. doi:10.1016/S0161-6420(96)30394-1.
  5. ↑ Foster, Robert E; Murray, Timothy G; Byrne, Sandra Frazier; Hughes, J.Randall; Gendron, B.Kym; Ehlies, Fiona J; Nicholson, Donald H (September 2000). "Echographic features of medulloepithelioma". American Journal of Ophthalmology. 130 (3): 364–366. doi:10.1016/S0002-9394(00)00542-0.
  6. 1 2 3 4 5 Vajaranant, Thasarat S.; Mafee, Mahmood F.; Kapur, Rashmi; Rapoport, Mark; Edward, Deepak P. (February 2005). "Medulloepithelioma of the Ciliary Body and Optic Nerve: Clinicopathologic, CT, and MR Imaging Features". Neuroimaging Clinics of North America. 15 (1): 69–83. doi:10.1016/j.nic.2005.02.008. PMID   15927861.
  7. ↑ Peyman, GA; Mafee, MF (May 1987). "Uveal melanoma and similar lesions: the role of magnetic resonance imaging and computed tomography". Radiologic clinics of North America. 25 (3): 471–86. PMID   3554332.
  8. ↑ De Potter, Patrick; Shield, Carol L.; Shields, Jerry A.; Flanders, Adam E. (November 1996). "The Role of Magnetic Resonance Imaging in Children with Intraocular Tumors and Simulating Lesions". Ophthalmology. 103 (11): 1774–1783. doi:10.1016/S0161-6420(96)30428-4.
  9. 1 2 FontR, Croxatto J, Rao N. Tumors of the optic nerve and optic nerve head: medulloepithelioma. In: Silverberg S, Sobin L, eds. AFIP atlas of tumor pathology: tumors of the eye and ocular adnexa. Washington, DC: American Registry of Pathology, 2006; 148–149.
  10. ↑ Davidorf, Frederick H.; Craig, Elson; Birnbaum, Lee; Wakely, Paul (June 2002). "Management of medulloepithelioma of the ciliary body with brachytherapy". American Journal of Ophthalmology. 133 (6): 841–843. doi:10.1016/S0002-9394(02)01432-0.
  11. ↑ Janss, Anna J.; Yachnis, Anthony T.; Silber, Jeffrey H.; Trojanowski, John Q.; Lee, Virginia M.-Y.; Sutton, Leslie N.; Perilongo, Giorgio; Rorke, Lucy B.; Phillips, Peter C. (April 1996). "Glial differentiation predicts poor clinical outcome in primitive neuroectodermal brain tumors". Annals of Neurology. 39 (4): 481–489. doi:10.1002/ana.410390410. PMID   8619526.
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