Gains of Chromosome 8 Are Confined to Mesenchymal Components in Pleuropulmonary Blastoma

Abstract

Pleuropulmonary blastoma, an aggressive tumor that is emerging as a distinct entity of childhood, is characterized by mesenchymal elements (including undifferentiated blastema and often cartilaginous, rhabdomyoblastic, or fibroblastic differentiation) and epithelium-lined spaces. We investigated two patients with pleuropulmonary blastoma, a 3-year-old boy and an 11-year-old girl, both with large cystic masses replacing one lung. In both children, the post-chemotherapy resection specimens showed more maturation of rhabdomyoblasts and more nuclear pleomorphism in all mesenchymal cell lines, compared with biopsies sampled before treatment. Karyotypic analysis demonstrated gains in chromosome 8 in both cases and 17p deletion in one case. Fluorescent in situ hybridization analysis demonstrated that the chromosome 8 gains were present in all mesenchymal elements, including undifferentiated blastematous, rhabdomyoblastic, fibroblastic, and chondroblastic areas. Epithelial cells showed no chromosome 8 gains. The chromosome 8 aberrations were not appreciably different in pre- versus post-chemotherapy tissue. Our findings substantiate previous reports that polysomy of chromosome 8 is a consistent feature of pleuropulmonary blastoma. Further, they indicate that clonal proliferation in pleuropulmonary blastoma is restricted to the malignant mesenchymal elements, supporting the notion that the epithelial components of this tumor are non-neoplastic.

Primary pleuropulmonary synovial sarcoma

“…7), although the former appeared more likely. This problem, common to lung tumors, is analogous to past controversy about the biphasic nature of pleuropulmonary blastoma 24, 28, 29. In the case of pleural tumors, the finding that all previously reported cases were of biphasic type whereas ours were only monophasic may be explained by similar reasoning, because entrapped and/or reactive mesothelium may have been mistaken for glandular differentiation in some prior cases.…”

Gain of chromosome 8q is a frequent finding in pleuropulmonary blastoma

“…The most consistent chromosomal anomaly is extra copies of chromosome 8, which has been found in many studies, approximating 75-80% of all cases studied. [10][11][12][13][14][15][16][17][18][19] A single case study has thus far been performed with CGH, also showing gain of almost the entire chromosome 8. 21 In our study, we confirm these findings by showing gain of at least the long arm of chromosome 8 in four of the five cases studied.…”

“…Cytogenetic studies have repeatedly reported trisomy of chromosome 8 or, more generally, gains of chromosome 8, in addition to complex genetic abnormalities. [10][11][12][13][14][15][16][17][18][19] Furthermore, trisomy of chromosome 2 has been reported by fluorescence in situ hybridization (FISH). 20 However, altogether these studies have investigated no more than 17 cases of pleuropulmonary blastoma.…”

Thirteen-Year-Old Child With a Malignant Chest Tumor Clinicopathologic Conference

“…In solid lesions, c-kit (CD117) positivity has been demonstrated in the spindle cells [27]. No consistent chromosomal alteration has been identified for PPB, although gain of chromosome 8q, trisomy 8, and loss of 17p are the most frequent abnormalities reported [19,[28][29][30][31][32][33][34][35][36][37][38].…”