Retinoblastoma Causes And Clinical Stages

Retinoblastoma Causes And Clinical Stages

Retinoblastoma represents a retinal tumor that occurs in young children aged between 1 and 4 years, caused by the mutation of the RB1 gene localized at the chromosome 13.

The most common form of retinoblastoma is hereditary (more than 60%) and the mutated gene can be inherited from one of the parents but it can also be a sporadic, non-hereditary form (35-40%) due to a defect that can occur in the chromosome 13 during the gene coding process.

The tumor cells have a very high rate of development thereforeretinoblastoma is the cause of multiple metastasis. Although in more than 70% of the cases the tumor is present unilateral , the tumor can also be present bilateral with variation in dimensions and localization.

Retinoblastoma Clinical Stages

The tumor develops in several clinical stages.

In first stage the tumor can be detected during occasionally eye examination. At this stage the presence of small tumors is noticeable . In this stage the tumor grows irregularly as a polycyclic, white-yellow colored spot. The tumor usually develops in the posterior pole of the retina but it can also be present in other parts of retina. As a malignant process it can have it's origins in the superficial or the deep layers of the retina either it can originate from the external layers of the retina.

Stage two is represented by the progressive ocular hypertension occured when the tumor invades the eyeball leading to  secondary glaucoma. The eye becomes painful red, through the pupil a tumor mass that protrudes can be observed. Leukocoria is also a very important sign which represents an abnormality of the pupil.  Usually at this stage, the child is brought to the doctor and diagnosed.

Exteriorization stage consists of the progression of the tumor outside the eyeball sclera and cornea. . Tumor invades the orbit and eyelid and can appear as a painful purple mass, brittle and hemorrhagic .Tumor invades the optic nerve along which it enters the skull.

Generalization stage, metastasis, is represented by the appearance of metastases in the brain, meninges, cervical lymph nodes, mediastinum, liver and bones. The tumor is composed of embryonic retinal cells, multiple retinoblastic mitosis, cells are arranged around vessels creating  a rosettes aspect. Extensive necrosis is usually present.

Differential diagnosis is made with retrolenticular fibroplasia, retinal detachment, Coats disease and intraocular metastases. If the disease was discovered in the state of orbital invasion chemotherapy associated with radiotherapy and orbital ablation is the prefered treatment option.