Metatypical skin cancer: causes, symptoms, diagnosis, treatment

Metatypic skin cancer (syn.: basosquamous cancer, mixed cancer, intermediate carcinoma) can develop on unchanged skin, but often occurs against the background of pre-existing basalioma, especially after radiotherapy. The clinical manifestations of metatypic cancer in most cases do not differ from the clinical picture of basalioma and usually correspond to its tumor and ulcerated forms. Metatypic cancer is observed more often in elderly males. Like basalioma, metatypic cancer is more often observed on the face, but can also occur in other places where basal cell cancer does not occur (for example, the skin of the extremities).

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Pathomorphology of metatypical skin cancer

Often has much in common with that of basalioma. Almost always, as in basalioma, a connection of tumor elements with the epidermis is revealed. Among the histological forms of metatypical cancer, the solid type of tumor with the presence of morphea-like structures or areas with adenoid differentiation predominates, however, morphea-like and adenoid tumor variants can also be observed separately. On this basis, I.A. Kazantseva et al. (1983) identified solid, morphea-like and mixed histological variants. In all of the above varieties, the tumor consists of cells resembling basaloid cells, but somewhat larger in size and with a more pronounced rim of eosinophilic cytoplasm. The characteristic "palisade-like" arrangement of cells along the periphery of tumor complexes, as is observed in basalioma, is preserved only in places or is completely absent. On this basis, metatypical cancer can be detected in cases where it occurs against the background of a pre-existing basalioma, which is observed quite often.

Against the background of solid, adenoid and morphea-like types, as a rule, keratotic foci are found, resembling "pearls" in squamous cell carcinoma. The abundance of histological variants, their similarity to basalioma complicate diagnostics. For more accurate diagnostics, methods of assessing the mitotic regime of the tumor have recently been used. I.A. Kazantseva et al. (1983), studying the mitotic regime of metatypical cancer and basaliomas, showed that mitotic activity in metatypical cancer is 2 times higher than in basalioma.

A characteristic feature of metatypical cancer in all observations was the appearance of multipolar and monocentric mitoses, bridges in the ana- and telophase, and three-group metaphases, which are absent in basaliomas, which are characteristic of all malignant tumors.