Enzinger And Weiss Soft Tissue Tumors 6th Edition Pdf Free Fix 50 LINK
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After three days a wide excision was carried out and the tumor was removed together with the two thirds of the left scapula and the overlying soft tissues. The remaining bone and soft tissue margins were widely free of tumor. Macroscopic and pathologic examination of the removed mass confirmed the primary diagnosis.
Apart from diversity in morphological features seen even in conventional SFT, two histologic variants (fat-forming and giant cell-rich) are also recognized. In addition, a malignant form and dedifferentiation are well recognized. Owing to diverse histological features and involvement of diverse anatomic locations, SFT can mimic other soft tissue neoplasms of different lineages including schwannoma, spindle cell lipoma, dermatofibrosarcoma protuberans, liposarcoma, gastrointestinal stromal tumor (GIST), malignant peripheral nerve sheath tumor (MPNST), and synovial sarcoma. SFT is classified as an intermediate (rarely metastasizing) tumor according to World Health Organization Classification of Tumors of Soft tissue and Bone, 5th edition. The management and prognosis of SFT differs from its malignant mimics and correct diagnosis is therefore important. Although SFT expresses a distinct immunohistochemical (IHC) profile, the classic histomorphological and IHC profile is not seen in all cases and diagnosis can be challenging. NAB2-STAT6 gene fusion has recently emerged as a sensitive and specific molecular marker and its IHC surrogate marker signal transducer and activator of transcription 6 (STAT6) has also shown significant sensitivity and specificity. However, few recent studies have reported STAT6 expression in other soft tissue neoplasms.
The vascular channels in SFT lack a connective tissue layer and the endothelial cells merge with surrounding tumor cells. Fibrotic background and perivascular fibrosis are not seen [20]. HPC-like vasculature can be seen in other mesenchymal tumors including various soft tissue sarcomas [5, 10]. This gave rise to a debate whether HPC was a distinct tumor entity or simply a non-specific histomorphological pattern seen in various tumor types [28,29,30].
Like other soft tissue tumors, dedifferentiation is also observed in SFT. The dedifferentiated variant is extremely rare and shows abrupt transition to a low or high-grade sarcoma with adjacent conventional SFT. The dedifferentiated component is mostly in the form of spindle cell sarcoma not otherwise specified or undifferentiated pleomorphic sarcoma (Fig. 5a&b) and can rarely show osteosarcomatous or rhabdomyosarcomatous differentiation [38,39,40,41,42,43]. Dedifferentiation may be seen in primary or recurrent tumors. It can be associated with loss of expression of immunohistochemical markers and newer molecular alterations. Occasional squamous and neuroendocrine differentiation has also been reported in SFTs [40].
STAT6 IHC marker can also be expressed in some other soft tissue neoplasms such as well differentiated liposarcoma (WDL) or dedifferentiated liposarcoma (DDL), desmoid fibromatosis, unclassifiable sarcoma, neurofibroma, myxoid liposarcoma, undifferentiated pleomorphic sarcoma, low grade fibromyxoid sarcoma, synovial sarcoma (SS) and ovarian fibroma [17, 61, 62]. Doyle et al. observed positive STAT6 expression in 4 out of 35 (11%) cases of DDL [61]. In a large study, Demicco et al. assessed STAT6 expression in 1781 non-SFT mesenchymal tumors and observed strong nuclear expression in 4% cases. Tumors which demonstrated positive expression included unclassifiable sarcoma (8/65{12%}), WDL and DDL (49/409{12%}), desmoid tumor/fibromatosis (14/184{8%}), neurofibroma (3/60 {5%}), clear cell sarcoma (1/19{5%}), myxoid liposarcoma (2/108{2%}) and undifferentiated pleomorphic sarcoma (2/173{1%}). Ouladan et al. evaluated STAT6 expression in 374 non-SFT mesenchymal tumors and positive nuclear staining was observed in only 4 (1%) cases including 2 cases of WDL, 1 case of DDL and 1 case of SS [63]. STAT6 expression was also found in a small subset of non-neoplastic tissue including scar tissue and adipose tissue [62]. In a series of prostatic SFT and smooth muscle tumors of uncertain malignant potential (STUMP), the sensitivity and specificity of STAT6 for SFT was 91 and 75% respectively [64]. The expression of STAT6 in SFT is exclusively nuclear but other tumors may show both nuclear and cytoplasmic staining [62].
Gene expression profiling studies have also identified overexpression of GRIA2 gene and aberrant expression of GRIA2 protein in SFT [12]. This protein is usually expressed in central nervous system tissue and epithelia of some organs but can also be expressed in soft tissue tumors such as SFT and dermatofibrosarcoma protuberans (DFSP) [54]. In one study, overall frequency of GRIA2 IHC expression in SFT was 80%. The frequency was 86% in malignant cases and 100% in dedifferentiated cases [17].
In superficial locations, two soft tissue tumors with CD34 expression need to be distinguished from SFT [22]. These tumors are DFSP and superficial CD34 positive fibroblastic tumor (SCD34PFD). DFSP is a dermal based tumor usually composed of fairly uniform spindle cells with elongated nuclei arranged in storiform pattern and infiltrating into the subcutaneous adipose tissue. SCD34PFD is also a dermal based tumor comprising of sheets and fascicles of spindle to epithelioid cells. Tumor cells have moderate cytoplasm and may show moderate to marked atypia [74]. In comparison to these tumors, SFTs have relatively more defined borders and heterogeneous cellularity. Molecular studies on DFSP typically show translocation t(17;22) and/or supernumerary ring chromosome r(17;22) [75].
Myxoid change in SFT is well reported and a number of other soft tissue tumors with myxoid features must be excluded. These tumors include low grade myxofibrosarcoma, low grade fibromyxoid sarcoma and myxoid liposarcoma [25,26,27, 55, 60, 80, 81]. Some of these tumors may express CD34 and occasional cases with STAT6 expression have also been reported. Careful examination of tumor for cases showing conventional SFT morphology along with diffuse and strong nuclear STAT6 expression leads to accurate diagnosis [61, 62].
Soft tissue tumors with epithelioid morphology such as epithelioid sarcoma and epithelioid angiosarcoma sometimes need to be considered in the DD [25]. SFT with giant cells is a rare occurrence and the DD of this morphological form include soft tissue sarcomas with giant cell component and nodular fasciitis [25, 82].
Epithelioid morphology, mimicking carcinoma, is a key or defining feature of several soft tissue tumors and may be seen in a wide variety of other tumors. This review will focus on those tumors defined at least in part by their epithelioid morphology, in particular epithelioid sarcoma, epithelioid malignant peripheral nerve sheath tumor, and sclerosing epithelioid fibrosarcoma. The role of loss of the SMARCB1 tumor-suppressor gene in the pathogenesis of these epithelioid soft tissue tumors will be discussed, as will their differential diagnosis with non-mesenchymal tumors, in particular carcinoma and melanoma.
Malignant peripheral nerve sheath tumors are relatively rare, accounting for roughly 5% of all soft tissue sarcomas.52, 53 Approximately one-third occur in association with neurofibromatosis type 1. EMPNST accounts for
Sclerosing epithelioid fibrosarcoma (SEF) is a relatively newly described malignant fibroblastic tumor, considered by the current WHO classification of soft tissue and bone tumors to represent a distinct variant of fibrosarcoma.58 However, there is considerable morphological and genetic data to suggest a link between SEF and low-grade fibromyxoid sarcoma (LGFMS) (see below).59, 60, 61, 62, 63
Although epithelioid change may be seen in a wide variety of soft tissue tumors, this morphology is most characteristic of ES, MERT, EMPNST, and SEF. The precise relationship between SMARCB1 abnormalities and epithelioid morphology remains to be fully elucidated; however, the presence of such aberrations in ES, MERT, and EMPNST suggests that this is more than a coincidence. From a practical perspective, improved recognition of the various sarcomas that may show epithelioid morphology is critical for their distinction from other epithelioid malignancies and for correct treatment. 1e1e36bf2d