The authors examined by immunohistochemical methods two Spinocellular (SCC) and two basocellular (BCC) carcinomas on the background of xeroderma pigmentosum (XP) from two sisters - patients of the Dermatovenereological Clinic at the University in Martin. The bioptic materiál was taken 18 years previously when it was excised from the patients who died in the meantime. The tumours tissue was deposited in paraffin blocs. The authors applied to the prepared preparations a broad spectrnm of cytokeratins (CK) from the group HMW, AEl/AE3, CK 14, CK 18, CK 19 as well as other monoclonal antibodies. Consistent with data in the literatura from the area of immunological pictures of SCC and BCC, the tumours cell populations were positiva in particular when HMW and AE1/AE3 were used. Contrary to BCC, in both SCC the tumour cells expressed CK 14. Simple epithelia were detected quite exceptionally in both types of carcinomas. 5-100 protein was present occasionally in non-tumourous cells (most likely Langerhans cells) in all examined tumours. PCNA was detected in 90 % nuclei of SCC tumour cells which suggests their marked proliferating activity. The picture was supplemented by a major amount of melanin dispersed in the tumours masses of both types of tumours.

        Key words: xeroderma pigmentosum - spinocellular carcinoma - basocellular carcinoma - immunohistochemistry - cytokeratins