Photoreceptor differentiation of retinoblastoma: An electron microscopic study of 29 retinoblastomas |
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Authors: | Yasuo Tajima Shigeru Munakata Yasuo Ishida Tohru Nakajima Isamu Sugano Koichi Nagao Kensei Minoda Yoichiro Kondo |
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Institution: | Department of Surgical Pathology, Teikyo University School of Medicine, Ichihara Hospital, Ichihara;Laboratory of Electron Microscopy, Teikyo University School of Medicine, Ichihara Hospital, Ichihara;Department of Ophthalmology, Teikyo University School of Medicine, Ichihara Hospital, Ichihara;Department of Pathology, School of Medicine, Chiba University, Chiba, Japan |
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Abstract: | Retinoblastomas exhibit a unique form of differentiation to produce cell elements similar to those seen in a photoreceptor cell. An ultrastructural study was performed on 29 cases of retinoblastoma to further clarify the cytologic characteristics of the tumor cells. The age of the retinoblastomas averaged 17.1 months and the tumor cells showing photo-receptor differentiation were demonstrated in 10 cases (35%). The findings were especially notable in retinoblastomas with Flexner-Wintersteiner rosette formation (seven cases, 28%). Similar photoreceptor differentiation was also evident in solid cell clusters without rosette formation (four cases, 14%). The presence of photoreceptor elements was assumed to be significantly frequent both in Flexner-Wintersteiner rosettes and in the solid cell clusters. The cell cytoplasm also showed proliferation of long mitochondria and microtubules, reflecting photoreceptor differentiation. The hereditary-type retinoblastoma showed more advanced cell differentiation than the non-hereditary type. Photoreceptor differentiated retinoblastoma showed rather indolent growth compared with the undifferentiated type, and the former can expect a curative treatment by operation. These observations provide additional findings of the biological nature of retinoblastomas. |
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Keywords: | intraocular tumor photoreceptor differentiation retinoblastoma ultrastructure |
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