Ewing Sarcoma/Primitive Neuroectodermal Tumor of the Liver: A Late Presentation With an Extremely Rare “Large Cell” Variant

Abstract

Ewing Sarcoma (ES)/primitive neuroectodermal tumour (PNET) is a mesenchymal tumor typically belonging to the family of “small round-cell tumors”. Typically, patients present in the first three decades of life. Although PNETs can occur in numerous solid organs, they are extremely rare in the liver. We report a case of a 33-year-old male who presented with worsening right upper quadrant abdominal pain and jaundice for one month. His laboratory studies were as follows: Total Bilirubin 12.2 Direct Bilirubin 7.6 Alkaline Phoshatase 484 Aspartate Aminotransferase 144 Alanine Aminotransferase 153. Computed Tomography scan of the abdomen revealed multiple liver lesions, the largest measuring 10.4 x 7.1 cm (Figure 1), as well as intrahepatic ductal dilatation. A biopsy of this lesion was consistent with sheets of large atypical epithelioid cells with vesicular nuclei, prominent nucleoli, and vacuolated cytoplasm diffusely infiltrating the liver parenchyma with patchy necrosis (Figure 2). These findings represent ES/PNET, but the histologic appearance shown (Figure 1) represented a rare “large cell” variant.2345_A Figure 1 No Caption available.2345_B Figure 2 No Caption available.The Ewing Family of Tumors includes ES and PNET.1 There is considerable overlap between the two, sharing a common and unique translocation t(11; 22) (q24; q12).2 ES/PNET is a member of the family of “small round cell tumors”. Although it can occur in numerous solid organs, it is an exceptionally rare tumor entity. Liver involvement is even rarer and is usually in the form of metastasis.2 The majority of patients with PNET are younger than 30 years of age.3 Three unique aspects of our case are as follows: late presentation, a “large cell” variant indicating an atypical ES/PNET, and liver involvement. To the best of our knowledge, this is only the fifth case reported involving primarily the liver. Furthermore, this is the only reported case involving the liver in an adult over the age of 30 years with a “large cell” variant. Most patients are diagnosed when metastasis has already occurred and prognosis is extremely poor.