| Abstract | Spitz neoplazme distinktivna su skupina melanocitnih tumora okarakterizirana specifičnim kliničkim, patohistološkim i molekularnim obilježjima. Dijele se na Spitz nevuse, maligne Spitz melanome te intermedijarne atipične Spitz tumore (AST) koji predstavljaju dijagnostički vrlo izazovne lezije. Specifične pokretačke mutacije u Spitz tumorima najvažniji su distinktivni faktor ovih lezija u usporedbi s drugim melanocitnim neoplazmama, a neke od najčešćih su fuzije onkogena ALK, ROS1, NTRK1, NTRK3, MET i RET koji kodiraju tirozin kinazne receptore te fuzije onkogena MAP3K8 i BRAF koji kodiraju serin/treonin kinaze. Aktualna istraživanja usmjerena su na korelacije između patohistoloških značajki i molekularnih promjena u svrhu povećanja moći razlikovanja benignih od malignih Spitz lezija. U našem smo istraživanju analizirali kliničke i patohistološke značajke te imunohistokemijski profil 24 Spitz nevusa i 24 AST-ova. Patohistološka analiza obuhvaćala je tip stanica, pagetoidnu ekstenziju, limfocitnu upalu, Kamino tjelešca, stanični pleomorfizam, mitotsku aktivnost te pigmentaciju. Semikvantitativna imunohistokemijska analiza provedena je nakon bojenja preparata klasičnim biljezima p16, Melan-A, HMB45 i Ki67 te nekonvencionalnim protutijelima ALK, ROS1 i Pan-TRK. U AST-ovima je utvrđen veći broj malignih patohistoloških značajki (najznačajnija razlika pronađena je u intenzitetu pagetoidne ekstenzije, P=0.02) izuzev odsutnosti Kamino tjelešaca te duboko smještenih dermalnih mitoza. Klinička obilježja maligniteta (promjer i dubina lezija) također su izraženija u AST-ovima, no bez statističke značajnosti. Među klasičnim imunohistokemijskim markerima najintenzivnija razlika pronađena je u Ki67 profilu koji upućuje na veću proliferativnost AST-ova (P=0.01). Ekspresiju ALK, ROS1 i Trk proteina u međusobno smo isključivom obrascu dokazali u po 4% Spitz nevusa, dok je u skupini atipičnih Spitz tumora ekspresija navedenih proteina prema istom redoslijedu dokazana u 8%, 17% odnosno 33% lezija. Uočeno je da ekspresija ROS1 proteina korelira s naglašenom pagetoidnom ekstenzijom, a dominacija epiteloidnog tipa stanica u lezijama s ekspresijom ALK, ROS1 i Trk proteina potencijalno je distinktivno obilježje navedenih lezija. Potreban je nastavak našeg istraživanja uz pomoć citogenetičkih ili molekularnih tehnika poput sekvenciranja sljedeće generacije u svrhu analize konkordantnosti imunohistokemijske ekspresije ispitivanih proteina i genskih fuzija. |
| Abstract (english) | Spitz neoplasms comprise a spectrum of melanocytic tumors which include benign Spitz nevi, malignant Spitz melanomas and atypical Spitz tumors (AST) for which precise distinction between nevi and melanomas is very challenging. Specific driver mutations are the most important distinguishing factor of Spitz lesions, and some of the most common are tyrosine kinase fusions of ALK, ROS1, NTRK1, NTRK3, MET and RET, as well as serine-threonine kinase fusions of MAP3K8 and BRAF. Current studies are focused on correlations between pathohistological features and molecular changes in order to increase the power to distinguish between benign and malignant Spitz neoplasms. In our research, we analyzed the clinical and pathohistological features, and the immunohistochemical profile of 24 Spitz nevi and 24 ASTs. Pathohistological analysis included cell type, pagetoid extension, lymphocytic infiltration, Kamino bodies, cellular pleomorphism, mitotic activity and pigmentation. Semiquantitative immunohistochemical analysis was performed after staining the preparations with classical markers p16, Melan-A, HMB45 and Ki67, and unconventional antibodies ALK, ROS1 and Pan-TRK. A greater number of malignant pathohistological features were found in ASTs (intensity of pagetoid extension showed most significant difference, P=0.02) except for the absence of Kamino bodies and deeply located dermal mitoses. Clinical features of malignancy (diameter and depht of lesions) were also more pronounced in ASTs, although without statistical significance. Among the classical immunohistochemical markers, the most intense difference was found in the Ki67 profile, which points to a higher proliferative nature of ASTs (P=0.01). Moreover, ASTs showed expression of ALK in 8% of lesions, ROS1 in 17% and Trk in up to 33%, while Spitz nevi showed expression of each protein in 4% of lesions. In all cases expression of these proteins was mutually exclusive. It was observed that the expression of ROS1 protein correlates with a notable pagetoid extension, and domination of epithelioid type of cells might be potential distinguishing feature of Spitz tumors which express ALK, ROS1 or Trk proteins. Further research using cytogenetic or molecular techniques such as next generation sequencing is necessary to test concordance between expression of the proteins and gene fusions. |
