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Query: UMLS:C0677930 (primary tumor)
 20,210 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Anaplasia, defined by the presence of extreme nuclear and mitotic atypia, is a potent marker of adverse prognosis in Wilms tumor (WT). Anaplastic WT cells apparently have increased resistance to therapy rather than increased aggressiveness. The distribution of anaplasia should therefore have critical prognostic relevance. The original definitions for focal anaplasia (FA) and diffuse anaplasia (DA) were based on quantitative rather than topographical criteria and lacked prognostic significance. A new definition was developed based on the distribution of anaplastic changes within the tumor: FA applies only to tumors with anaplasia confined to one or a few discrete loci within the primary tumor, with no anaplasia or marked nuclear atypia elsewhere. This revised definition was evaluated in 165 cases with anaplastic WT entered on the third and fourth National Wilms Tumor Study. Only three relapses and one death occurred among 39 cases with FA, regardless of tumor stage, a result comparable to that for nonanaplastic WT. Eight children with metastases at diagnosis and FA in the primary tumor were alive and free of relapse; 22 of 23 children with stage IV DA WT died of tumor. This new definition reinforces the importance of carefully documenting the exact site from which each tumor section is obtained.
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PMID:Focal versus diffuse anaplasia in Wilms tumor--new definitions with prognostic significance: a report from the National Wilms Tumor Study Group. 871 92

The initial presentation of follicular thyroid carcinoma is rarely related to metastatic lesions. Presented here is the case of a 70-year-old woman with the initial presentation of a 13-cm chest wall mass identified as a metastatic follicular thyroid carcinoma. The chest wall lesion had features of a poorly differentiated carcinoma with areas of necrosis, an insular growth pattern focally and increased mitotic activity. A small follicular carcinoma was subsequently identified. The primary tumor was a 1-cm well-differentiated follicular carcinoma with capsular and vascular invasion. This represents a rare presentation of a follicular thyroid carcinoma with initial recognition of a large, dedifferentiated metastatic lesion from a small primary carcinoma. Dedifferentiation and metastasis in the context of microcarcinoma is an exceptionally rare event and suggests other mechanisms may be involved in disease spread other than simply increased cell proliferation.
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PMID:Follicular thyroid carcinoma presenting as a massive chest wall tumor. 2322 18

Solitary fibrous tumor (SFT) is a ubiquitous mesenchymal neoplasm of deep soft tissue with variable and often unpredictable biological behavior. The lineage is presumed to be fibroblastic, and histological features range from benign to overtly malignant with rare tumors showing "dedifferentiation" or transformation to undifferentiated pleomorphic sarcoma. Dedifferentiation in mesenchymal neoplasms is a phenomenon of histologic progression of a well-differentiated neoplasm to a high-grade sarcoma, which can differentiate along divergent lines. It is extremely uncommon to encounter "transdifferentiation" to non-mesenchymal lineage and still maintaining the driver genetic event of the primary tumor. Herein, we report two diagnostically challenging SFTs with transformation to neuroendocrine and squamous phenotypes. The index case is a pelvic malignant SFT, which metastasized to the liver as a high-grade neuroendocrine carcinoma. The second case is a recurrent brain tumor initially presenting as a typical SFT and evolving into a dedifferentiated SFT with foci of squamous differentiation. Positive immunohistochemical stains for CD34 and STAT6 and the detection of NAB2-STAT6 fusion supported the diagnosis of dedifferentiated SFT in both cases. In the first case, molecular study also demonstrated that both the pelvic primary and liver metastasis harbored the same NAB2-STAT6 fusion. Dedifferentiation to a non-mesenchymal lineage/lineage infidelity can be a potential diagnostic pitfall in these tumors.
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PMID:Solitary fibrous tumor with neuroendocrine and squamous dedifferentiation: a potential diagnostic pitfall. 2930 7