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   Table of Contents      
ARTICLES
Year : 1981  |  Volume : 29  |  Issue : 1  |  Page : 51-54

Diktyoma


Department of Ophthalmology and Pathology, Medical College, Calcutta, India

Correspondence Address:
G N Seal
13/B-Durga Pithuri Lane, Calcutta 700012, West Bengal
India
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Source of Support: None, Conflict of Interest: None


PMID: 7287128

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How to cite this article:
Seal G N, Gupta S K. Diktyoma. Indian J Ophthalmol 1981;29:51-4

How to cite this URL:
Seal G N, Gupta S K. Diktyoma. Indian J Ophthalmol [serial online] 1981 [cited 2019 Dec 11];29:51-4. Available from: http://www.ijo.in/text.asp?1981/29/1/51/30994

The group of medullo-epitheliomata which mimics embryonic retina before its strata are differentiated is called embryonal medullo­epithelioma or diktyoma. The name, diktyoma was coined by Fuch[1] in 1908 because of the net-like structure of the tumour cell arrange­ment. Although closely related to retinoblas­toma, dictyomata differ from the former in several ways-neither bilateral nor multicentric in origin nor show any hereditary tendency.

The tumours are relatively rare and only some 50 cases have been reported.

They occur in young children with no sex predilection. The average age of occurrence is about 3 years although congenital presence is not uncommon. Clinical diagnosis is not us­ually possible. The growth commonly presents itself as unilateral buphthalmos, cataract or dislocation of the lens or staphyloma. If obser­ved in the early stage, it appears as a whitish irregular, non-pigmented mass arising from the ciliary body or alternately, bulging into the anterior chamber as if arising from the iris. So far as our knowledge goes, only three or four cases of diktyoma has been reported from India.

Because of its rare incidence, a case of diktyoma in the very early stage is being presented.


  Case report Top


A young girl of four and a half years was brought to the out-patient department, with the complaint of a whitish cystic growth in the pupillary area of the left eye. The mass was first noticed in the pupillary region about 6 months back which was gradually increasing in size since then. The child also complained of recurrent pain in the affected eye. She was taken to an ophthalmologist who had noted a raised ocular tension in affected eye for which tab. acetazolamide was prescribed. The case was then referred to this department for further investigations and treatment.

Examination showed that right eye was normal with 6/6 vision. Left Eye had he visual acuity of less than 6/60. Cornea appeared translucent due to epithelial oedema. Anterior chamber was shallow in the lower and inner quadrant. Pupil was half-dilated and immobile. In the medial half of the pupil, there was a grayish-white, loculated cystic mass extending from 10 o'clock to 5 o'clock position. The mass appeared to come from behind the iris, ocular tension was moderately raised with the globe little enlarged.

Slit-lamp : Anterior chamber was shallow in the infero-medial quadrant with the peri­pheral iris adherent to the cornea. In the affec­ ted quadrant, the iris was somewhat thickened and appeared being pushed from behind. At 6 o'clock, there was a prominent feeding vessel coming from the angle of the anterior chamber and entering the iris near the lower end of the growth.

The fundus could not be seen due to haz­iness of the media. The preauricular gland was not enlarged. X-rays of the orbit and chest showed nothing abnormal. W.R. was negative. Transillumination was also negative.

Provisional Diagnosis-A cystic growth arising from ciliary epithelium, most probably a diktyoma.

The left eye was enucleated on 11.8.78 under general anaesthesia and sent for histopa­thology. The orbital cavity did not show any extra-ocular extension. The post-operative recovery was uneventful and the child was discharged from the hospital on the tenth day and advised out-patient department for periodic follow-up.

Histopathology

Macroscopic-When the eyeball was bisect­ed sagittally, the specimen showed a grayish ­white irregular mass of about 10 mm. across the ciliary region and iris root. The mass slightly displaced the lens to the opposite side. The iris root was considerably thickened and adherent to the corneal periphery in the affected quadrant obliterating the angle of the anterior chamber [Figure - 2].

Microscopic-The tumour appeared to arise from the non-pigmented epithelium of the ciliary body pushing the iris in front of it. The iris and the angle of the anterior chamber in the affected segment were also infiltrated by the tumour cells. The growth presented a net­like or polycystic structure. The cysts were lined by a thin layer of columnar epithelium. In some areas of the tumour, the cells occurred in solid conglomerations with rosette forma­tions resembling a true retinoblastoma. The tumour cells did not contain pigment. No islets of cartilage or hyaline depositions were observed within the growth [Figure - 3].


  Discussion Top


Diktyoma mostly arise from the non-pig­mented ciliary epithelium of young children of either sex. Reese[2] published a report of a case of diktyoma arising in the posterior retina and optic nerve. When the patient is observed in the early stages as in our case, the tumour presents a characteristic picture. A whitish, irregular non-pigmented growth arises from the ciliary body and/or iris and grows anteriorly in front of the lens surface and behind the iris which is being pushed forward. In course of time, it tends to embarrass the filtration angle leading to secondary glaucoma and enlargement of the globe. In the present case, there was a grayish-white mass with shallowness of the anterior chamber in the infero-nasal quadrant associated with raised ocular tension. The progress of the tumour is usually slow and may be observed or suspected for several years without any distant metastasis. Though locally malignant, distant metastasis usually do not occur. Two cases of distant metastasis are, however, on record[3] one in the lymph nodes and other in the skull, brain and lungs. Reese reported a case of diktyoma of the optic nerve which proved fatal within a year due to intra­cranial extension. Kalidasan et al[4] reported another case where secondaries in the skull bone and right orbit developed a month after enucleation of the globe. In our case, enuclea­tion was done about 6 months after the onset of the growth and no local or distant extension has occurred so far.

The usual age at which the growth occurs is in infancy and early childhood although it maybe present at birth. The average age of incidence is 3 years; its occurrence in older age group has also been reported. The age of the girl under our observation is four and a half years. Gareis5 described a case of diktyoma which occurred in left eye of a 18-month-old child.

A characteristic microscopic feature of these tumours is that they have no stroma. In some places, the remains of the invaded tissue acts as the stroma. The malignant nature of the tumour is indicated by its histologic features and infiltrating tendency. Normally, the tumour tissue is composed of numerous rows of nuclei which, on section, appear as layers of embry­onic retina. It may grow as membranes com­prising of single row of nuclei which may fold on itself so that, on cross section, appear as two or several rows forming intricate convolu­tions and interlacing membranes. The tumour cells may also occur in solid conglomerations with formation of rosettes. Sometimes, there are formation of islets of cartilage with partial calcification. In the present case, the malignant case, the malignant cells are collected into solid conglomerations with rosette formation inter­spersed with cystic spaces. No islets of carti­lage were noted.

The diagnosis of diktyoma should always be borne in mind whenever one comes across a case of unilateral buphthalmos or glaucoma in a child, particularly in presence of an inter­calary staphyloma, a cataractous or dislocated lens or cystic formation in the anterior segment of the globe. The present case which was brought to us in the early stage, exhibited a non-pigmented cystic mass in the infero-nasal cystic mass in the infero-nasal quadrant behind the iris and the picture was very suggestive of the diagnosis of diktyoma. The case reported by Kalidasan et al was first diagnosed to be an early ease of panophthalmitis and true nature of the affection was obvious only after the pathology report and appearance of secon­daries.


  Summary Top


A case of diktyoma in the early stage occur­ring in a girl aged four and a half years is presented[6].

 
  References Top

1.
Fuchs E, 1908, V. Grafe, Arch. Ohhthalmol, 68: 534  Back to cited text no. 1
    
2.
Reese, A.B., 1965, "Tumours of the Eye and Adnexa" Sect. X. Armed Forces Institute of Pathology. Washingtn, D.C.  Back to cited text no. 2
    
3.
Duke-Elder, S., 1966, System of Ophthalmology, Vol. IX, Henry Kimpton, London. P. 790  Back to cited text no. 3
    
4.
Kalidasan, C.S. and Natarajan, K., 1975. Ind. J. Ophthal mol. 23 .13  Back to cited text no. 4
    
5.
Gareis, R., 1955, Klin Monatsbl. f. Augenh. 127 : 344  Back to cited text no. 5
    
6.
Keshavachar, K.R. and Junnarkar, R.V.,, 1960, Brit. J. Ophthalmol. 44 : 693-695.  Back to cited text no. 6
    


    Figures

  [Figure - 1], [Figure - 2], [Figure - 3]



 

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