Chapters authored
Pathology of Alveolar Soft Part Sarcoma
Alveolar soft part sarcoma (ASPS) is a rare orphan sarcoma of uncertain differentiation according to the latest WHO classifcation of soft tissue tumors with a somewhat indolent clinical course. The common histomorphological alveolar-type presentation is unique. It is usually not graded according to the French Federation of Cancer Centers grading system, but nonetheless defined as a high-grade sarcoma. The tumor adopts a clinical pattern with a distinctive natural history marked by local recurrences up to 50% of cases and a high prevalence of metastases in such diverse sites such as the lung, liver, brain, bone that can occur more than 10 years after the primary event. ASPS is driven by a specific recurrent nonreciprocal translocation der(17)t(X;17)(p11;q25). This chimeric gene fusion is also found (albeit in the balanced mode) in a subset of renal cell carcinomas in the young. Nevertheless, its high specificity and sensitivity in ASPS is a recognized feature and accurate diagnosis requires trained pathologists and molecular testing. Prognostication is based on age, size of tumor, primary site, and the presence or not of metastasis.
Part of the book: Advances in Soft Tissue Tumors
Emerging Mesenchymal Tumors
Two new soft tissue entities are described. First, GL1-altered epitheloid mesenchymal tumors comprise two reported molecular subtypes: one with GLI1 fusion and the other with GLI1 amplification, both of which show increased expression of GLI1 RNAm. While most tumors described are malignant, a small subset provisionally termed distinctive nested glomoid neoplasm pursue an indolent course even with regional lymph nodes metastatic spread. There is no known association between prognostication and molecular subtype. Second, the so-called pseudoendocrine sarcoma is considered to be a sarcoma of intermediary grade with a morphology reminiscent of neuroendocrine tumors and characterized by recurrent mutations of the B-catenin gene. This lesion occurs more and less in elderly patients and is most often found in paravertebral area, which makes complete resection surgically relatively challenging.
Part of the book: Soft Tissue Sarcoma and Leiomyoma