Metatypical basal cell carcinoma: from the primary tumour to a generalized metastatic process - description of diagnostics and combination therapy of an extremely rare skin cancer

Introduction. Basal cell carcinoma (BCC) is the most common form of skin cancer. The hallmarks of this carcinoma are the absence of distant metastases and local malignancy. Metatypical basal cell carcinoma (MTBBC) is rare variant that it is considered to be a more aggressive form, with a higher potential for metastases and recurrence. Probably due to its very rare occurrence, data on pathogenesis, course and treatment are inconsistent. Case report. An unusual and very aggressive course of MTBBC with multiple metastases is prtesented. Repeated histopathological evaluation shows the diagnostic difficulties in this type of tumour. Therapeutic attempts, including targeted therapy with vismodegib, were unsuccessful. Conclusions. This case showed that it should always be taken into account that each case of diagnosed BCC may turn out to be metatypical variant with a much more aggressive course and worse prognosis. For this reason, intensive follow-up after a completed treatment is recommended.