Ocular Cytopathology

An atlas that features the cytologic findings of the normal features and diseases of the eye.

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Thursday, September 29, 2005

CHAPTER 6 Vitreous Abnormalities page 1

CHAPTER 6 Abnormalities of the Vitreous Body

Most abnormalities of the vitreous body (vitreous) are too subtle to be diagnosed by intraocular washings alone. These subtle changes are diagnosed by careful biomicroscopic examination in the living patient or with the dissecting microscope in the enucleated specimen. However, there are a few important conditions, such as amyloid, silicone retinopathy, and asteroid hyalosis, that are evident by examination of extracted vitreous. Other conditions, such as persistent hyperplastic primary vitreous, are considered in the clinical diagnosis of malignant tumors in children and it is important to be aware of their existence. Vitreous hemorrhage and hemoglobin spherulosis are presented in Chapter 5.

PERSISTENT HYPERPLASTIC PRIMARY VITREOUS

Persistent hyperplastic primary vitreous (PHPV) is a congenital condition most commonly unilateral in which there is persistent hyaloid vasculature and mesenchymal tissue from the embryonic primary vitreous in a microphthalmic eye. [1, 2, 3] Fibrovascular tissue and mesenchymal tissue are attached laterally to elongated and centrally dislocated ciliary processes (Figure 6-1 and 6-2). The lens-iris diaphragm may be anteriorly displaced and produce secondary angle-closure glaucoma. Cartilage, mature adipose tissue, and smooth muscle may arise from primitive mesenchymal tissue behind the lens. [4, 5, 6] There is frequently an accompanying total exudative retinal detachment (Figure 6-1). Clinically, the patient usually has a white papillary reflex (leukocria), poor vision, and a small eye. PHPV can be confused with retinoblastoma, although existence of leukocoria at birth and microphthalmia is highly suggestive of PHPV. If retinoblastoma is a series consideration in the differential diagnosis or if surgical repair is considered for PHPV, preoperative fine needle aspiration or intraocular washing may be used. Smears show spindle cells and retinal tissue (Figure 6-3). Unlike retinoblastoma, the cells of PHPV are usually more cohesive and do not exhibit extensive necrosis.

ASTEROID HYALOSIS

Asteroid hyalosis is a disorder in which white-yellow smooth refractile spheres are suspended in the collagenous framework of the vitreous body. It is often unilateral, but can be bilateral. It is more common in older people. [7] The opacities are composed of complex lipids, calcium, and phosphorous. [8, 9, 10] Histochemically, the matrix of the opacities stain with periodic acid-Schiff, alcian blue, Sudan black B, and oil red O. [11] clinically asteroid hyalosis is often asymptomatic with good visual acuity. However, it may be very dense and it may obscure vision. [12, 13] In addition, the poor funduscopic view occasionally prevents adequate laser photocoagulation in patients with concomitant retinopathy (Figure 6-4). Vitrectomy may be indicated to improve vision or to improve the view of the fundus for the surgeon. [14] Cytologic specimens reveal amorphous round bodies that are birefringent in polarized light (Figures 6-5 and 6-6). There may be an associated foreign-body reaction. [10]
The cause of asteroid hyalosis is not known. Even though lipid is present in the yellow particles, there is no clear association with diabetes and hypercholesterolemia. [15, 16, 17]
References:
1. Reese AB. Arch Ophthalmol 1949;41:527-549.
2. Reese AB. AJO 1955;40:317-331.
3. Haddad R, Font, RL, Reeser F. Surv Ophthalmol 1978;23:123
4. Font RL, Yanoff M, Zimmerman LE. Arch Ophthalmol 1969;82:43-50
5. Manschot WA. Arch Ophthalmol 1958;59:188-203
6. Reese AB, Payne F. AJO 1964;29:1-19
7. Rutherford CW. Arch Ophthalmol 1933;9:106
8. Verhoeff FH. AJO 1921;4:155-160
9. March W, Shock D, O' Grady R. Invest Ophthalmol 1974;13:701705
10. Miller H, Miller B, Rabinowitz H, et al. Invest Ophthalmol Vis Sci 1983;24:133-136
11. Rodman HI, Johnson FB, Zimmerman LE. Arch Ophthalmol 1961;66:552-563
12. Engel HM, Green WR, Michels RG, Rice TA, Erozan YS, et al. Retina 1981;1:121-149
13. Renaldo DP. Retina 1981;1:252-254
14. Lambrou FH, Sternberg P, Meredith TA, Mines J, Fine SL. Ophthalmic Surg 1989;20:100-102
15. Smith JL. JAMA 1958;168:891-893
16. Hatfield RE, Gastineau CF, Rucker CW. Mayo Clin Proc 1962;37:513-514
17. Luxenberg MN, Sime D. AJO 1969;67:406-413






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