Which histologic findings are characteristic of primitive neuroectodermal tumor of the thoracopulmonary region (PNET)?

Updated: Dec 25, 2019
  • Author: Joseph F Tomashefski, Jr, MD; more...
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Answer

Askin tumors exhibit 3 patterns of cell organization: diffuse sheets of cells, tumor cells with a nesting arrangement separated by fibrovascular stroma, or serpiginous bands of cells with necrosis. [19] The neoplastic cells are round to oval with scant cytoplasm and a dense nucleus with evenly distributed coarse chromatin without prominent nucleoli. A moderate number of mitotic figures may be present. Homer-Wright–like neural rosettes may occasionally be seen. [19] PAS-diastase stain is usually negative for glycogen, although some tumors may stain positively, further blurring the histological distinction from classical EWS. [18]

Pathology of nonmesothelial cancers of the pleura. Pathology of nonmesothelial cancers of the pleura. A small round blue cell tumor is consistent with a primitive neuroectodermal tumor involving the chest wall of a 28-year-old woman. Small neoplastic cells are present in a diffuse pattern.

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