[Malignant melanoma treated with radical chemotherapy, resemblance histology of melanoma to soft tissue sarcomas, case report]

BACKGROUND

Malignant melanoma is considered to be highly resistant to chemotherapy, radiotherapy, hormonotherapy and standard immunotherapy (interleukin 2, interferon alpha). Radical surgery in the early stages of the disease is still the most efficient method. Since the development of immunotherapy and targeted therapy, the role of palliative chemotherapy for advanced disease may be changing.

CASE

A case report regarding 44-year-old woman with extensive tumor of the pectoral wall with contralateral axillary lymphadenopathy is presented. On the basis of imaging methods, histology and immunohistochemistry, the tumor was defined as a sarcoma. Due to PAX7-FKHR fusion gene positivity, rhabdomyosarcoma was the most probable classification. The patient was treated with radical chemotherapy including iphosphamide, vincristine, actinomycin D and doxorubicin with the effect of partial regression of the tumor. This enabled radical surgery of the chest wall tumor. Pathology proved 70% necrosis of the tumor. A contralateral axillary dissection was performed with a finding of two lymph nodes infiltrated with melanoma. The immunohistochemistry markers S100, HMB-45 and Melan A were positive. This resulted in a reclassification of the chest wall tumor to malignant melanoma. The following PET/CT scan was negative. A massive progression of the disease occurred after 5 months. B-RAF mutation leads to a plan of targeted therapy with vemurafenib.

CONCLUSION

The case demonstrates the limits of the sensitivity and specificity of immunohistochemical markers of melanoma and the ability of this tumor to imitate various tumors including soft tissue sarcomas. A rare -PAX7-FKHR fusion gene positivity considered specific for rhabdomyosarcoma was found. An extraordinary response to radical chemotherapy with surgical resection led to an improvement of the quality of life and to a prolonged survival comparable with the effect of new targeted treatment for malignant melanoma.

[Significance of urokinase and its inhibitors in the invasiveness and metastasing of malignant tumors]

Fibrinolysis is process, which leads to the degradation of fibrin to fibrin monomers. Fibrinolysis helps to regulate hemostasis and prevents the creation of inappropriately large thrombus, which could reduce blood flow to the bloodstream. The main enzyme involved in fibrinolysis is plasmin. Tissue plasminogen activator (tPA) and urokinase (uPA) are agents converting plasminogen into active plasmin, together with urokinase receptor (uPAR) and urokinase inhibitors (PAI 1, PAI 2, PAI 3 and protease nexin) form plasminogen activator system (PAS) which is among others also part of the metastatic cascade and significantly contributes to invasive growth and angiogenesis of malignant tumours. In contrast to tPA that is fundamental in fibrinolysis, uPA plays an essential role in tissue degradation as part of physiological and pathological processes. uPAR is a GPI (glycosylphosphatidylinositol)-anchored protein. The binding of uPA to uPAR results in activation of protein tyrosine kinase, protein kinase C and MAP kinase. At the same time, direct signalling pathway via Jak/STAT cascade utilising signalling transduction of Scr-like protein tyrosine kinase have also been described. uPAR expression is regulated by many growth factors, e.g. EGF, FGF-2 and HGF. It seems that individual PAS factors are involved in the process of rendering malignant tumors invasive. To what degree this influence is essential to specific malignancies, should be answered by further research. In the article the authors present a summary of findings about the interaction of fibrinolysis and tumor process, especially on the effects of urokinase and other activators and their inhibitors in metastasis of malignant tumors. The text contains information on the factors theirs introduction into practice is still the subject of numerous discussions, but in the future, individual PAS factors could play an important role in planning treatment strategies and also could become targets of targeted therapy.