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GUEST EDITORIAL
Year : 1989  |  Volume : 37  |  Issue : 4  |  Page : 162-163

Ocular tumours-some newer and controversial aspects


Prof. of Ophthalmology, BHU, Varanasi, India

Correspondence Address:
H V Nema
Prof. of Ophthalmology, BHU, Varanasi
India
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Source of Support: None, Conflict of Interest: None


PMID: 2638300

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How to cite this article:
Nema H V. Ocular tumours-some newer and controversial aspects. Indian J Ophthalmol 1989;37:162-3

How to cite this URL:
Nema H V. Ocular tumours-some newer and controversial aspects. Indian J Ophthalmol [serial online] 1989 [cited 2021 Feb 24];37:162-3. Available from: https://www.ijo.in/text.asp?1989/37/4/162/26059

Ocular tumours or neoplasms are benign and malignant. However, all benign tumours are not completely inno­cent, just as all malignant ones are not dangerous or fatal. Chemical carcinogens, radiant energy, oncogenic viruses and genes are capable of altering the growth behaviour of normal cells of the ocular tissues. In the recent past, substantial advances have been made in the diagnosis and treatment of ocular tumours. At the same time considerable controversies are generated in ocular oncology. These controversies are indeed inter­esting as well as thought provocative.


  Retinoblastoma Top


Retinoblastoma, a most common intra ocular tumour of childhood has its origin in the neuroreceptor cells of the retina. The incidence of the tumour is approximately 1 in 18000 births. It occurs both in hereditary and non­hereditary forms and is relatively often bilateral (8 to 35 percent) For the first time D group chromosome deletion in the skin fibroblast or a retinoblastoma patient was reported in 1963. Later it was hypothesised that majority of unilateral retinoblastomas are phenocopies due to somatic mutation, while all bilateral ones are genetically determined [1]. Recently, an oncogene predisposing to retinoblastoma in the autosomal dominant inherited cases has been identified. The genetic locus determin­ing retinoblastoma susceptibility was asigned to band q 14 chromosome 13 along with the gene for the polym,orphic marker enzyme esterase -D, by examination of cytogen­etic deletion. It is proposed that inactivation of both alleles of a gene located in the region of 13,g 14 resulted in retinoblastoma. Lee et.al. has now sequenced the gene of retinoblastoma isolated earlier. Incidently, it is the first human cancer gene isolated and sequenced [2].

The newer diagnostic modalities such as hypocyclodial polytomography, computerised trans-axial tomography, Nuclear magnetic resonance, A and B ultrosonography radionucleide scintigraphy with technitium diphosphate are more sensitive in the clinical diagnosis of retinoblas­toma. Besides A and B scans, M-scan Kinetic ultros­onography is also advocated as spontaneous vascular pulsations within the mass can be easily seen as box shaped [3].The estimation of Lactic dehydrogenase (LDH) activityin the tear, aqueous humour and serum of retino­blastoma patients may be helpful. Perhaps the determi­nation of LDH isoenzymes might even be more reward­ing.

It is depressing that retinoblastoma survivors are prone to develop secondary primary neoplasms (2 to 15 per­cent) irrespective of their treatment modalities. These primaries are often histologically distant from retinoblas­toma; most commonly osteosarcomas. The patients with the genetic form of retibnoblastoma are particularly sensitive to the carcinogenic effect of radiation.

Enucleation, Cobalt plaque irradiation, photocoagula­tion, cryo therapy and systemic chemotherapy are well established modalities for the management of retino­blastoma. The identification of the oncogene will cer­tainly open new vistas for more appropriate preventive and therapeutic protocols for retinoblastomas. The day is not far when biotechnologists would understand the basic biochemical alteration that influence the retinal cells to proceed to form retinoblastoma. Hopefully, the retinoblastoma can be prevented by the biotechnologi­cal gene correction in the future.


  Malignant melanoma of the uvea Top


Malingnant melanoma of the uvea is not a common intra ocular tumour in our population. It originates from mela­nocytes which are derived from the neural crest. Malig­nant melanomas of choroid are frequent, comprising of 85% melanomas of the uveal tract, while ciliary body and iris melanomas occur only in 9 percent and 6 percent of cases respectively. The tumour poses diagnostic prob­lems. Inspite of the availability of sophisticated proce­dures 2 to 5 percent cases remain misdiagnosed even at major ophthalmic centres. [4] Monoclonal antibodies (MoAb) have more affinity for melanoma cells in vitro. It is speculated that in the recent future the application of monoclonal antibodies is likely to increase diagnostic as well as therapeutic possibilities in malignant melanoma . [5]

Malignant melanoma of the uveal tract has become a topic of great controversy. The clinicians seem to be divided in their opinion on prognosis and treatment protocols. Some ophthalmologists advocated that ma­lignant melanoma of iris should not be dealt with by radical excision but be periodically followed with meticu­lous clinical documentation as the tumour rarely metas­tasises and the mortality is much less than in the tumours of ciliary body and choroid. The better outlook of iris melanomas is attributed to their tendency to present at an early stage in their development and remain localised for a long duration. On the other hand, the large tumour size, epitheloid cell type, and relative tendency for delayed presentation are the main factors for a poor prognosis for the patients of melanomas of the ciliary body and choroid than that of the iris . [6]

Owing to the poor prognosis of the melanomas of the posterior uvea, enucleation of the eye was the classical treatment of the disease. Recently, the value of enuclea­tion was questioned and it was suggested that perhaps the operation facilitates metastasis of the tumour cells and thus might worsen the prognosis. [7] To minimise the dissemination of neoplastic cells "no touch technique" of enucleation or radiation treatment prior to enucleation was introduced. However, a number of clinicians strongly advocate and prefer using alternative methods of man­agement of malignant melanoma. [8] Indeed each case must be treated on individual basis and generalisation be strictly avoided. Size, location, extent of melanoma, status of the other eye, age and general health of the patient must be taken into consideration before the modality of therapy is worked out. An eye with large tumour without useful vision warrant enucleation while conservative procedures be applied in eyes with small tumours and salvagable vision. The alternative modali­ties of management includes periodic follow-up, sup­ported with steroscopic coloured photographs, photoco­agulation, radidtherpy and local resections.Most pa­tients with systemic metastasis need palliative radiation and chemotherapy. May be the immunotherapy pro­vides an effective management of the malignant mela­noma of the uvea in the near future.

 
  References Top

1.
Francois, Juleus: Hereditary and malignant tumours of the eye. In symposiyum on surgical and medical management of congenital anomalies of eye. Trans. New Orleans Aced. Ophthal. St. Louis C.V. Mosby, 1968, p. 220.   Back to cited text no. 1
    
2.
Lee, W. H. et at.: Human retinoblastoma susceptibility gene cloning idenfication and sequence. Science. 235:1394-99,1987.   Back to cited text no. 2
    
3.
Dogan, O.K. ; Gunalp, I. and Gundaz, K. : Comparison of the clinical, histopathological and ultrasonographic, histopathologic findings In retinobias­toma. Proc. XXV Int. Cong. Ophthal., Rome Amsterdam, Kugler and Ghedini, 1987. pp. 97-902.  Back to cited text no. 3
    
4.
Davidroff, F.H. ; Leston, A.D. ; Weiss, E.T. and Lenine, E.: Incidence of misdiagnosed and unsuspected choroidal melanomas : a 50 year experience, Arch. Ophthalmol. 101; 410, 1983.  Back to cited text no. 4
    
5.
Bomanji, J.; Garner, A.; Prasad, J. at al.: consideration of ocular melanoma with cutaneous melanoma antibodies. B.J.O. 71, 647-50,1987  Back to cited text no. 5
    
6.
Hungerford, J.: Editorial : Prognosis in Ocular melanoma; B.J.O. 73 689-692, 1989.  Back to cited text no. 6
    
7.
Mc Lean, I.W.; Foster, W.D.; Zimmerman, L.E.; Mankin, D.G.; Inferred natural history of uveal melanomas. Invest. Ophthalmol. Vis. Sci.:19: 760-70, 1980.   Back to cited text no. 7
    
8.
Shields, J.A.: Current treatment of Malignant melanoma of the posterior uvea. In Recent advances in Ophthalmology. Eds. Davidson, S. I. and Fraunfelder, F.T., Edinburgh, Churchill Livingstone, 1985. p. 173-183.  Back to cited text no. 8
    




 

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