Flexner–Wintersteiner rosette

Flexner–Wintersteiner rosettes in Retinoblastoma.

Flexner–Wintersteiner rosette is a spoke and wheel shaped cell formation seen in retinoblastoma and certain other ophthalmic tumors.^[1] A rosette is a structure or formation resembling a rose, such as the clusters of polymorphonuclear leukocytes around a globule of lipid nuclear material, as observed in the test for disseminated lupus erythematosus.^[1]

Characteristics

The tumor cells that form the Flexner–Wintersteiner rosette surround a central lumen containing small cytoplasmic extensions of the encircling cells. Unlike the center of the Homer Wright rosette, the central lumen is devoid of fiber-rich neuropil. Like the Homer Wright rosette, the Flexner–Wintersteiner rosette represents a specific form of tumor differentiation.^[2][3][4][5] Electron microscopy reveals that the tumor cells forming the Flexner–Wintersteiner rosette have ultrastructural features of primitive photoreceptor cells.^[6] Furthermore, the rosette lumen shows similar staining patterns as in rods and cones,^[7] suggesting that Flexner–Wintersteiner rosettes represent a specific form of retinal differentiation. In addition to being a characteristic finding in retinoblastomas, Flexner–Wintersteiner rosettes may also be found in pinealoblastomas and medulloepitheliomas.^[2]

History

Flexner–Wintersteiner rosettes were first described by Simon Flexner (1863–1946), a physician, scientist, administrator, and professor of experimental pathology at the University of Pennsylvania (1899–1903). Flexner noted characteristic clusters of cells in an infantile eye tumor which he called retinoepithelioma.^[8][9][10] A few years later, in 1897, Austrian ophthalmologist Hugo Wintersteiner (1865–1946) confirmed Flexner’s observations and noted that the cell clusters resembled rods and cones.^[11] These characteristic rosette formations were subsequently recognized as important features of retinoblastomas.

References

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