Pathology of endometrial biopsy diagnosed PNET according to the characteristic of small blue round cells with Homer-Wright rosettes and Friend leukemia integration 1 transcription factor (FLI-1) positive.
Sequential pathology of endometrial biopsy displayed that the tumor was composed of monotonous small round primitive cells with high nuclear-to-cytoplasmic ratio in papillary, nest, and sheet patterns [Figure 2]a with Homer-Wright rosettes [Figure 2]b.
(B) In some areas, characteristic Homer-Wright rosettes
could be seen (H&E, x200).
Common features of ENB on light microscopy include small, round-to-oval cells with coarsely granular chromatin, multiple small nucleoli, prominent nuclear membranes, and scant cytoplasm with pseudo rosette or occasional Homer-Wright rosettes
separated by fibrous septa.
Some of the cells clustered around a central area of eosinophilic granular material, forming so-called Homer-Wright rosettes
(Figure 3, B).
Gross inspection reveals a lobular shape with either dark brown, yellow, or gray-white areas of necrosis or hemorrhage.[sup.13] The histologic hallmark of PNET is formation of Homer-Wright rosettes
or pseudorosettes involving hyperchromatic cells.
(10) A PNET has morphologic evidence of neural differentiation, which is demonstrated histologically by Homer-Wright rosettes
, immunohistochemically by expression of at least 2 neural markers, or ultrastructurally by the presence of neural elements.
The neoplastic growth is composed of sheets of undifferentiated small blue cells with occasional Homer-Wright rosettes
. These cells have basophilic chromatin and frequent mitosis.
Fibrillary areas were visible (Figure 2, A), and the tumor cells often formed typical Homer-Wright rosettes
. Mitoses were rare.
Rosettes were observed with cells surrounding a central core of fibrillary material (Homer-Wright rosettes
) (Figure 1).
True perivascular pseudorosettes or Homer-Wright rosettes
were not noted.