Intra-abdominal EWSR1/FUS-CREM-rearranged malignant epithelioid neoplasms: two cases of an emerging aggressive entity with emphasis on misleading immunophenotype

CREB family (CREB1, ATF1, and CREM) gene fusions are defining markers in diverse mesenchymal neoplasms (clear cell sarcoma, angiomatoid fibrous histiocytoma, and others). However, neoplasms harboring EWSR1-CREM/FUS-CREM fusions are rare and poorly characterized. We describe two cases (55-year-old male with 7.5 cm renal mass and 32-year-old female with 5.5 cm mesenteric mass) illustrating their misleading immunophenotypes. Histologically, both showed eosinophilic and focally clear epithelioid cells arranged into sheets, nests, and trabeculae. Immunohistochemistry showed ALK, EMA, and AE1/AE3 immunoreactivity suggesting ALK-rearranged renal cell carcinoma (Case 1) and coexpression of keratin, EMA, synaptophysin, and chromogranin-A, suggesting neuroendocrine neoplasm (Case 2). Targeted RNA sequencing revealed EWSR1-CREM (Case 1) and FUS-CREM (Case 2) fusions. These cases add to the spectrum of CREM fusion-positive intra-abdominal epithelioid neoplasms. Their unusual immunophenotype and unexpected sites represent major pitfalls, underline a wide differential diagnosis, and emphasize the value of molecular testing in correctly diagnosing them.

Management of renal tumors during pregnancy: case reports

Background Renal tumors during pregnancy are rare and the treatment requires evaluation of both the patient and the fetus. No consensus or guidelines has been proposed or verified in this field. We successfully managed three renal tumor cases during pregnancy and reviewed the relative literature. Case presentation In the first renal cell carcinoma case diagnosed in the 21st week of pregnancy, laparoscopic retroperitoneoscopic partial nephrectomy was performed in the 26th week of pregnancy. In the second renal cell carcinoma case diagnosed in the 3rd week of pregnancy, laparoscopic retroperitoneoscopic radical nephrectomy was carried out after the abortion. In the third angiomyolipoma case who was diagnosed before pregnancy but received no treatment, we performed laparoscopic retroperitoneoscopic partial nephrectomy during the 17th week of pregnancy due to the rapid enlargement of the tumor. Conclusion Although no consensus or guidelines for the management of renal tumors in pregnant patients has been proposed or verified, the general rules of kidney tumor management in non-pregnant patients and the guidelines for surgery in pregnancy could be referred to. Renal tumors found in pregnant patients require an individualized treatment regimen involving surgical timing, routes, techniques, and excision ranges, which should be decided by both the patients and the surgical teams.