Clinicopathologic And Molecular Cytogenetic Reserch On Inflammatory Myofibroblastic Tumor And Low-grade Myofibrosarcoma

Backgrounds: Inflammatory myofibroblastic tumor (IMT) and low-grade myofibrosarcoma (LGMS) are intermidiete tumors( rarely metastasizing) in the spectum of myofibroblsts. Both were controversial in the tumor nature and sarcoma cocept and can be mistaken for benign lesions or sarcomas clinicopathologically. Identifing neoplastic myofibroblasts without electron microscopy is crucial in diagnostic and reaserch. The molecular defined criteria for representing subcellular features of myofibroblasts are required to be completed. Clonal abnormalities with rearrangements of chromosome of 2p23 and the ALK gene have been reported in a few cases. Whether these abnormalities among IMTs represent a distinct subset is unknown. The expression of ALK has recently been shown to occur in some sarcomas. Whether the ALK family of neoplasms includes LGMS is also unknown. Moreover, the ALK gene and protein in several kind of neoplasms have been found in different abnormal states (ALK gene rearrengments,extra copys without rearrangment or combinded) and different protein pattens( ALK chimeric or full-length protein).Obejctives: This dissertation has focused on the morphologic, immunophenotypic and genetic features of IMT and LGMS in order to provide helpful information for diagnosis and therapy. The aim was firstly to further define their clinical and pathologic features, secondly to make a tentative effert to find new molecular markers which represent subcellular features of myofibroblasts, thirdly to elucidate the genetic features of ALK gene among IMT and its potential clinical significances, and to investigate the presence of ALK gene expression in LGMS.Methods: 41 cases tumors from 24 paticients of IMT and 10 patients of LGMS were identified from the files and studied by the techniques including lightmicroscopy, immunohistichemisty, electron microscopy, reverse transcription-polymerase chain reaction (RT—PCR) and interphase fluorescence in situ hybridization (FISH). We exsamined the clinicopathological features of the above cases in the first part. The immunocytochemical expression of fibronectin, laminin, cailponin, h-caldesmon and other related markers was examined and evaluated, and the ultrastructrures was examined in 7 of them by electronic microscopy in the second part. In the third part, ALK gene status was analyzed by interphase fluorescence in situ hybridization (FISH), and the expression of ALK transcripts was assessed using RT—PCR, furthermore, ALK protein expression was evaluated immunihistochemically with monoclonal antibody ALK1 and polyclonal antibody ALK. Findings were correlated with clinical features and outcome.Results: IMT and LGMS displayed a series of histological architectural and cellular features. Follow-up in 14 patients of IMT (mean: 58 months) revealed local recurrence in 2 cases, and no distant metastases were documented. Follow-up in 8 patients of LGMS (mean: 41 months) revealed local recurrence in 2 cases, and distant tough metastasis in one case.Immunohistochemistry demonstrated variations in IMT and LGMS. Firstly, frequent expression of high level of calponhu a-SMA (alpha-smooth muscle actin), MSA(muscle specific actin)and fibronectin could be detected, in IMT with positive rates 100% (18/18), 95.8% (23/24), 100% (20/20) and 100% (18/18) respectively, and in LGMS with positive rates 100% (9/9), 100% (10/10), 90% (9/10) and 100% (9/9) respectively. Secondly, less frequent expression of low level of desmin and laminin could be detected, in IMT with positive rates 33.3% (7/21) and 81.8% (18/22) respectively, and in LGMS with positive rates 40% (4/10) and 42.9% (3/7) respectively. Thirdly, no expression of h-caldesmon could be detected in both IMT (0/20) and LGMS (0/10), as well as the expression of S-100 protein, CD34, myoglubin and CD99. Finally for CK, the expression is different between IMT and LGMS, with a low level and low positive rate 13.6 % (3/22) in the former, whereas no positive in the latter. Ultrastructural examinationin seven cases showed the characteristic features of myofibroblasts.Fluorescence in situ hybridization on 6 of the positive cases showed 2p23 ALK rearrangements in five cases. ALK transcripts were identified in 42% (8/19) of IMT by RT-PCR, with the form of IC-ALK positive/EC - ALK. ALK protein was detected immunohistochemically in 40.9% (9/22) of IMT, and No positive was detected in LGMS (0/9) by both RT — PCR and immunohistochemical assays. IMT with ALK abnormalities by immunohistochemistry, RT — PCR and/or fluorescence in situ hybridization originated in bladder (2cases), trachea and bronchus (2cases), vocal cords (lease), stomach (lease), orbit (lease) and extremities (2cases). The mean age was 14.8 years, with a male/female ratio of 3.5, and all of patients had no evidence of disease at last follow-up. The IMT without ALK abnormalities occurred in older patients (with a mean age of 39.9 years), were more frequent in females, and had 2cases of recurrences.Conclusion: For the first time, we report a large group of myofibroblastic tumors (IMT and LGMS) of China. Our data conform that ALK positivity is common in IMT. We demonstrate ALK is negative in LGMS by both RT-PCR and immunohistochemical assays, suggesting ALK is likely to be not common in LGMS and can be helpful in diagnosis and differential diagnosis. ALK transcripts in IMT were the truncated or chimeric forms rather than the full-length (wild-type) ALK. We provide some initial observations to answer the question about ALK family.In a preliminary tentative effort of defining the subcellular features of myofibroblasts with fibronectin, laminin and other actin related proteins, we detected frequent expression of high level of calponin, ot-SMA, MSA fibronectin, lower frequent of exoression of lower level of desmin and laminin, and no expression of h-caldesmon in both IMT and LGMS, suggesting these markers are likely to be more helpful in diagnosis and differenticial diagnosis. To our knowledge, this represents the first reported cases in a group of IMT with involvement of the expression of fibronectin and laminin. In contrast to previous...