Calcifying nested stromal-epithelial tumors of the liver: a clinicopathologic, immunohistochemical, and molecular genetic study of 9 cases with a long-term follow-up.

There is a rare primary liver tumor that has been reported as "ossifying stromal-epithelial tumor" (3 cases), "desmoplastic nested spindle cell tumor" (4 cases), and "nested stromal-epithelial tumor" (6 cases). Herein we report 9 cases of this tumor, including 3 previously reported, from the files of the Armed Forces Institute of Pathology. All tumors were discovered incidentally in patients between 2 and 33 years of age. Four had a history of calcified hepatic nodules since childhood (ages 4 to 10 y). One had Cushing syndrome that abated after excision. Eight patients had a partial hepatectomy and 1 underwent liver transplantation. The tumors ranged from 5.5 to 20 cm and had a characteristic histologic appearance with irregular, sharply circumscribed nests and islands of bland-appearing spindled to focally epithelioid cells, surrounded by a cellular desmoplastic stroma. The tumor nests had focal psammoma-like calcifications with or without ossification. Immunohistochemistry demonstrated at least focal positivity for keratin cocktail AE1/AE3/LP34 in all 9 cases, and Wilms tumor suppressor gene (7/7) with variable staining for other epithelial (except keratins 7 and 20), neural, and mesenchymal markers. None of the tumors was positive for Ewing sarcoma-primitive neuroectodermal tumors, desmoplastic small round cell tumor, and SYT-SSX fusion transcript. Follow-up revealed that 1 patient had 2 local recurrences successfully treated by radiofrequency ablation. The patient who underwent liver transplantation died of postoperative complications. Six patients were alive and well up to 22 years after surgery. We propose the name "calcifying nested stromal and epithelial tumor" for this rare but distinctive clinicopathologic entity of uncertain histogenesis. On the basis of currently available information, this tumor is best considered a low-grade malignancy.