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Few cases have previously been observed in the mediastinum and extremities [1�C3]. Less common sites include buttocks and the retroperitoneum [3]. Cases as rare as intracardiac presentation Quinapyramine of MTTs have been reported [15, 16]. MTTs typically present as a rapidly enlarging mass with associated pain and compressive symptoms to adjacent organs. Woodruff et al. established the original histological criteria for the diagnosis of the malignant triton tumors. He stated that the tumors must arise along the course of a peripheral nerve or in a preexisting neurofibroma in patients with NF-1. Additionally, the tumors must display identical growth characteristics of Schwann cells. Finally, they must contain ��bona fide�� rhabdomyoblasts originating from the body of peripheral nerve tumor and not from extension or metastasis of an extrinsic rhabdomyosarcoma http://www.selleckchem.com/products/GDC-0449.html [14]. Daimaru et al. further broadened the definition to encompass the sporadic forms in patients without NF-1, which, he argued, are microscopically comparable malignant schwannomas with focal rhabdomyoblasts, and tumors consisting predominantly of rhabdomyoblastic differentiation with focal Schwann cell elements occurring within a nerve or in patients with NF-1 [17]. Today, the diagnosis of MTT is generally made according to these criteria as well as immunohistochemical findings for cell origin tracing. Nerve sheath differentiation is confirmed by S-100 protein and Leu-7 (CD57) positivity. Rhabdomyoblastic differentiation is confirmed by immunohistochemical positivity for desmin, actin, and myogenin [3, 12]. Through these findings, the diagnosis of MTT can be positively made and the proper course of treatment can be pursued. However, one major area of concern for clinicians is the rate of tumor occurrence and regrowth after appropriate treatment. Local recurrence rate varies from 22% to 43% [1, 7, 18] and metastasis has been reported to occur in 20�C50% of cases [7, Selleck MS-275 18]. Recurrence is dependent on several factors, including tumor location, extent of surgical excision, degree of differentiation and growth pattern, and performance status and comorbidities [6]. Tumors originating from head and neck have lower rates of recurrence, whereas tumors originating from the trunk, buttocks, retroperitoneum, and CNS have lower rates of recurrence. Wong et al. reported that MTTs involving nonextremity sites have a higher likelihood to recur. Lymphatic invasion and lymph node involvement has not been reported in patients with MTT [6]. The most common site of metastasis is lung [1], but common extra pulmonary metastases include bone, liver, peritoneum, and the central nervous system. PET/CT is helpful in detecting distant metastases [1]. Anecdotal views vary regarding the impact of NF-1 status on survival. Zakzouk et al.