ABSTRACT.Purpose: To report a patient with a history over 25 years of a slowly growing, large, invasive crateriform tumour filling the anterior part of the orbit. Methods: A 61-year-old male presented with a large tumour of the left orbit. Exenteration was performed with subsequent histological analysis of the excised mass. Results: The main tumour showed the characteristic features of a keratoacanthoma. However, the posterior aspect of the tumour disclosed the morphology of a squamous cell carcinoma. Six months later, the patient presented with metastases to lymph nodes, lung and mediastinal tissue. A leukemoid reaction was diagnosed by fine needle biopsy. Conclusion: The giant variety of keratoacanthoma may fail to regress and can transform into a squamous cell carcinoma. In our patient, the development of a chronic lymphoid leukemia raises the possibility that it may be the underlying cause for the transformation of the posterior part of the keratoacanthoma into a frank squamous cell carcinoma.