Nested (ossifying) stromal epithelial tumor of the liver: case report.

Nested stromal-epithelial tumor (NSET) of the liver is an extremely rare primary hepatic tumor with uncertain malignant potential. To date, only 11 cases have been described. We describe the case of a 2 1/2-year-old girl with an incidental liver mass. The mass was discovered on follow-up abdominal imaging for asymptomatic hydronephrosis diagnosed on antenatal ultrasound. Needle biopsy showed a mixed stromal and epithelial process in a nested pattern, with foci of ossification and no significant pleomorphism or necrosis. The nest cells stained with WT-1, cytokeratin 18, and CD56. Ossifying stromal epithelial tumor of the liver was strongly suspected. The findings were confirmed in the subsequent partial hepatectomy specimen. To our knowledge, this is the 12th case of NSET in the English-language literature and the 3rd case of NSET associated with genitourinary system abnormalities. Possible associations with dysregulated WT-1 expression are discussed.

Characterization of acrylic polyamide plastic embolization particles in vitro and in human tissue sections by light microscopy, infrared microspectroscopy and scanning electron microscopy with energy dispersive X-ray analysis.

Vascular embolization is a well-established practice for the treatment of tumors and vascular lesions. Rounded beads (microspheres) of various materials (collagen, dextran and trisacryl-polymer-gelatin) were developed to solve problems encountered with earlier versions of embolic material. We performed histochemistry, Fourier transform infrared microspectroscopy and scanning electron microscopy with energy dispersive X-ray analysis on two uterine and one hepatic specimen with unidentified intravascular foreign material, and examined a reference embolization product for comparison. The hematoxylin and eosin stained tissue sections showed multiple foci with unidentified intravascular foreign material and fibrous obliteration of vessel lumens. Only one case had a clinical history of previous embolization but without specifying the material used. One case was submitted for identification of a 'parasite'. The material stained positively with Sirius red and mucicarmine, variably with Masson's trichrome stain and Movat pentachrome, and did not stain centrally with periodic acid Schiff with diastase. Infrared spectrophotometric analysis of the material from all three cases demonstrated the spectrum of acrylic polyamide plastic. A control sample of EmboGold exhibited infrared microspectroscopic spectra similar to the three tissue specimens. Analysis by scanning electron microscopy with energy dispersive X-ray analysis demonstrated some differences in elemental composition between the tissue sections and the selected reference material. To our knowledge, this is the first report of infrared spectrophotometric analysis with scanning electron microscopy with energy dispersive X-ray analysis of an acrylic polyamide plastic embolization product both in vitro and in human histologic tissue sections. In cases lacking appropriate clinical information, identification by these methods and/or a panel of special stains may assist pathologists unfamiliar with this material's light microscopic appearance.