Undifferentiated (embryonal) sarcoma of the liver: ultrastructure, immunohistochemistry, and DNA ploidy analysis of two cases

Distinguishing undifferentiated embryonal sarcoma of the liver from biliary tract rhabdomyosarcoma: a Children's Oncology Group study

Morphologically, the distinction between undifferentiated embryonal sarcoma of the liver (UESL) and biliary tract rhabdomyosarcoma (RMS) can be uncertain because of some shared pathologic similarities. Patients with UESL have been consistently but erroneously enrolled in Children's Oncology Group (COG) treatment protocols because UESL was equated with RMS, despite the differing primary treatment modalities of these entities. Review of COG pathology files yielded 20 cases of UESL that were compared to 25 cases of biliary tract RMS. Clinicopathologic features including immunohistochemical staining were examined. In the UESL cases, the male:female ratio was 1:1 and the median age was 10.5 years. Histologically, hyaline globules and diffuse anaplasia were consistently present. The cases of RMS had a male:female ratio of 1.8:1 with a median age of 3.4 years and routinely lacked diffuse anaplasia and hyaline globules. Polyclonal desmin and muscle-specific actin were variably immunoreactive in UESL and RMS; however, myogenin and myogenic regulatory protein D1 (MyoD1) were uniformly negative in UESL and routinely positive in the majority of biliary tract RMS. Myogenin, in particular, was highly significant (P = 0.0003) in distinguishing RMS from UESL. With a median follow-up of 8 months, 11 of 18 patients with UESL were still alive. The estimated 5-year survival for biliary tract RMS was 66%. Establishing the correct diagnosis of these distinct clinical and pathologic entities is important, as surgery alone may be curative in UESL, whereas initial chemotherapy is often recommended for the treatment of biliary tract RMS.

Immunohistochemical analysis of embryonal sarcoma of the liver

Embryonal sarcoma of the liver is a rare, aggressive malignant tumor that typically occurs in children and teenagers. Microscopic features include spindle, oval, or stellate cells with poorly defined cell borders, nuclear pleomorphism and multinucleation, and variable immunoreactivity to cytokeratin, vimentin, and alpha-1-antitrypsin. Intracellular and extracellular PAS-positive, diastase-resistant hyaline globules are commonly present. The authors evaluated a panel of IHC stains to better define the pattern of immunoreactivity in this tumor. Embryonal sarcomas of the liver were identified from archival files and were immunostained with antibodies: cytokeratin AE1/3, hepatocyte, SMMS, myogenin, calponin, h-caldesmon, desmin, S100, vimentin, CD34, C-kit (CD117), CD10, ALK-1, PE10, Bcl2, p53, and Ki-67. Six cases were identified. Patient age ranged from 6 to 24 years. Tumors ranged from 10 to 20 cm and contained spindled and epithelioid areas with PAS-positive, diastase-resistant globules and atypical cells with focal multinucleation. All cases showed immunoreactivity with vimentin and five showed immunoreactivity with Bcl2. Focal immunoreactivity was seen with cytokeratin AE1/3 in three cases, CD10 in four, calponin in two, desmin in one, and p53 in four. All tumors were negative with hepatocyte, myogenin, CD34, SMMS, h-caldesmon, PE10, ALK-1, and S100. No cytoplasmic staining was seen with C-kit. The proliferation index ranged from 30% to 95%. The diagnosis of embryonal sarcoma is based on typical morphologic features in a large liver tumor occurring in a young patient. The most useful IHC stains help to exclude tumors such as hepatoblastoma, hepatocellular carcinoma, embryonal rhabdomyosarcoma, and other sarcomas.

Mesenchymal Hamartoma of the Liver With an Interstitial Deletion Involving Chromosome Band 19q13.4: A Theory as to Pathogenesis?

Mesenchymal hamartoma of the liver is the third most common liver tumor of infancy. The lesion is primarily mesenchymal in origin, believed to arise from a developmental abnormality in the formation of ductal plates during late embryogenesis. Several studies have revealed a recurrent translocation in mesenchymal hamartomas, all involving a breakpoint at chromosome band 19q13.4. We present a case with a deletion involving this locus. A 10-month-old girl presented with an asymptomatic abdominal mass. The 21.0-cm tumor arose from the surface of the liver. The cut surfaces displayed multiple cysts with intervening loose fibrous tissue. Microscopically, the tumor was mostly composed of edematous connective tissue with intervening cysts, islands of hepatocytes, and haphazard branching bile ducts. Cytogenetic analysis revealed an interstitial deletion on the long arm of chromosome 19(q13.1q13.4). The patient was discharged on postoperative day 4 without complications. The cytogenetic findings support the involvement of an alteration of a gene at chromosome band 19q13.4 in the pathogenesis of mesenchymal hamartoma of the liver.

Hepatic mesenchymal hamartoma with translocation involving chromosome band 19q13.4: a recurrent abnormality

We report a case of mesenchymal hamartoma of the liver in an 8-month-old male child, in which the cytogenetic analysis revealed a balanced translocation, t(11;19)(q13;q13.4). This is the fifth description of a cytogenetic abnormality in mesenchymal hamartoma and is similar to the four cases reported previously in that one of the breakpoints involved chromosome band 19q13.4.

Hepatic tumors in children

Although they account for only 1% to 4% of solid tumors in children, hepatic tumors and pseudotumors offer a diagnostic challenge to the clinician seeing only an occasional case. Metastatic lesions such as neuroblastoma, Wilms' tumor, and lymphoma are the most common neoplasm seen in the liver, but 10 distinct primary tumors and pseudotumors of the liver occur with some regularity, and a few others may be seen rarely, including leiomyosarcoma, rhabdoid tumor, and endodermal sinus tumor. Five of these neoplasms--hepatoblastoma, infantile hemangio-endothelioma, mesenchymal hamartoma, undifferentiated embryonal sarcoma, and embryonal rhabdomyosarcoma of the biliary tree--occur only in children and are the major focus of the article.

Undifferentiated embryonal sarcoma of the liver: results of clinical management in one center

PURPOSE

This study was undertaken to review the authors' clinical experience with undifferentiated embryonal sarcoma of the liver (UES) in children, focusing on the clinical presentation and results of treatment.

METHODS

A retrospective analysis of all children who have undergone treatment for UES during the 15-year period from 1984 through 1998 was performed.

RESULTS

Seven patients (4 boys and 3 girls) ranging in age from 20 months to 12 years at the time of diagnosis were identified. All presented with large abdominal masses and normal liver function test results. All underwent complete tumor resection; trisegmentectomy was required in 4 of these cases. All patients received postoperative chemotherapy. Two patients suffered tumor recurrence at 12 and 29 months; both of these patients died of their disease. Another patient died of complications related to chemotherapy. The other 4 patients are alive with no evidence of disease after 19 to 150 months' follow-up.

CONCLUSIONS

Undifferentiated embryonal sarcoma of the liver presents as a large hepatic tumor. Operative resection is difficult, but combined with adjuvant chemotherapy offers the best hope for cure.

Third report of t(19q)(13.4) in mesenchymal hamartoma of liver with comments on link to embryonal sarcoma

We report the third known case of mesenchymal hamartoma of the liver (MHL) with a balanced translocation involving a common breakpoint, 19q13.4. A common clonal chromosome abnormality appears to characterize an important subset of MHL, some of which may be low-grade neoplasms. We found no consistent karyotype abnormality in a post-treatment sample of embryonal sarcoma of the liver (ESL). Reports of coexistent MHL and ESL in two patients and detection of 19q abnormalities in two ESLs appear to support Stocker's hypothesis of a histogenetic link between these two rare liver lesions. More data are needed to clarify this relationship. It is possible that MHLs are etiologically heterogenous and may be developmental disorders, disruptions, or neoplasms.

Primary hepatic malignant tumor with rhabdoid features. A histological, immunocytochemical, and electron microscopic study of four cases and a review of the literature

Malignant tumors of the liver with rhabdoid features (MTR) are uncommon: Only 14 previous cases are reported in the literature. These tumors are characterised morphologically by sheets of large polygonal cells with abundant eosinophilic cytoplasm containing a periodic acid Schiff's-positive hyaline globular inclusion and vesicular nuclei with a central prominent nucleolus. Immunohistochemically, the inclusions at least show positivity for vimentin and epithelial markers and sometimes for other antigens. Ultrastructurally, the inclusions are composed of whorled intermediate filaments. Despite the superficial resemblance to cells of muscle origin implied in the term rhabdoid, there is no immunohistochemical or ultrastructural evidence to support such a derivation. We describe four additional children with tumors of this type, in three of whom tumor cells showed focal membrane positivity for MIC-2 on immunostaining. Its expression in an hepatic MTR may indicate neuroepithelial differentiation. Hepatic MTR should be considered in the differential diagnosis of an undifferentiated primary liver tumor in an infant in whom the alpha-fetoprotein concentration is normal or only slightly elevated for age.

Telomeric associations in the progression of chromosome aberrations in pediatric solid tumors

Telomeric association (tas) is a cytogenetic phenomenon in which chromosome ends fuse to form dicentric, multicentric, and ring chromosomes. We observed clonal tas in six pediatric solid tumors of various types and histological grades studied using short-term in situ culture and G-banding techniques. These tumors included a neurilemoma, an undifferentiated (embryonal) sarcoma of the liver (UESL), two anaplastic astrocytomas (AA), one case of glioblastoma multiforme (GBM), and a neuroblastoma (NB) of the kidney. Cytogenetic data from all six tumors demonstrated multiple numerical and structural aberrations including tas. The tas appeared to be a secondary aberration in these tumors, however, it was possible to follow the progression of the telomeric chromosome aberrations in several cases. In all but one case (UESL) the loss of chromosome segments occurred. Tas of 11p was observed in three of the six tumors, two of which showed the subsequent loss of 11p (AA and AB). In addition, tas of 4p was seen in three tumors, two of which showed clonal tas of 4p with 22q. Tas of 10p, 21p, and 22q were all observed in at least two different tumors. The clonal telomeric fusions of 4p with 22q, recurring tas of 11p, and the subsequent loss of the short arm of 11 demonstrated here, suggests that some chromosome regions are subject to nonrandom instability and sometimes loss.

Cytopathology of undifferentiated (embryonal) sarcoma of the liver

We have studied one undifferentiated (embryonal) sarcoma of the liver (USL) by fine-needle aspiration cytology (FNAC) and have correlated the cytologic findings with those seen in the histologic sections. The main cytologic and immunocytochemical features were: cellular aspirates, mesenchymal clusters, disparity in individual cell size (small round cells, and multinucleated giant cells, sometimes bizarre), absence of biliary pigment, AFP-negative and vimentin-negative tumor cells, AFP-negative and PAS-positive hyaline globules, and apoptotic cells. Only immunostaining for alpha-1-antitrypsin, alpha-1-antichymotrypsin, and carcinoembryonic antigen were positive in tumor cells in histologic sections. The differential diagnosis should be carried out with rhabdomyosarcomas, hepatoblastomas, malignant fibrous histiocytomas, and poorly differentiated hepatocarcinomas. We think that the cytologic features observed in this case, evaluated both in the appropriate clinical context and in the light of the laboratory findings, may permit the correct diagnosis of this infrequent liver tumor. Nevertheless, more cases need to be studied to assess the reliability of our findings.

Mesenchymal hamartoma of the liver. DNA flow cytometric analysis of eight cases

BACKGROUND

Mesenchymal hamartoma of the liver is a rare lesion seen predominantly in childhood, which is believed to be either a developmental anomaly or reactive process. Because of recent reports of specific translocations involving chromosome 19 in mesenchymal hamartomas and certain ultrastructural and histologic features suggesting a relationship between mesenchymal hamartoma and undifferentiated (embryonal) sarcoma of the liver, some have speculated that mesenchymal hamartoma may be a neoplastic lesion with uncertain malignant potential.

METHODS

Because DNA aneuploidy can be useful as a marker for neoplasia, the authors decided to assess ploidy in paraffin embedded mesenchymal hamartomas using flow cytometry. The authors retrospectively examined mesenchymal hamartomas from eight children and evaluated the clinicopathologic features and the ploidy of the lesions.

RESULTS

Boys and girls were equally affected, and the mean age at presentation was 11 months. Lesions involved predominantly the right lobe of the liver, with a range of greatest dimension of 7-25 cm, and a mean weight of 651 g (though weights for three of the largest lesions were not recorded). Flow cytometric analysis of nuclei extracted from paraffin embedded tissue revealed that six of the eight lesions were DNA diploid, whereas two were DNA aneuploid (with DNA indices of 1.13 and 1.25). All of the lesions had a low S phase fraction.

CONCLUSIONS

The authors concluded that although most mesenchymal hamartomas are diploid, a subset of mesenchymal hamartomas is aneuploid. The finding of aneuploidy in mesenchymal hamartoma, in conjunction with the reported cytogenetic abnormalities, suggests that mesenchymal hamartoma may be a true neoplasm and not a developmental anomaly or reactive process.

An autopsy case of hepatic sarcomatoid tumor: immunohistochemical comparison with a sarcomatous component of hepatocellular carcinoma

A case of primary hepatic tumor exclusively composed of malignant cells with sarcomatous features is described and compared immunohistochemically with two cases of hepatocellular carcinoma (HCC) with a sarcomatous component. More than 30% of HCC cells were positively stained with anti-cytokeratin (CAM5.2), anti-albumin, anti-fibrinogen and anti-alpha 1-antitrypsin antibodies, and some with anti-epithelial membrane antigen. The present sarcomatoid tumor and the sarcomatous component with HCC showed similar immunohistochemistry; many tumor cells were strongly immunoreactive for vimentin and some positive for cytokeratin, albumin, fibrinogen and alpha 1-antitrypsin. Other immunohistochemical markers, indicating specific differentiations to lineage of macrophages, muscle cells, glial cells, endothelial cells and so forth, were not detected in sarcomatous tumor cells of all cases. These findings suggest that the present sarcomatoid tumor would belong to an anaplastic sarcomatous variant of HCC.