Porokeratosis belongs to a group of disorders of keratinization that are characterized by the histopathological feature of the cornoid lamella, a column of tightly fitted parakeratotic cells. The etiology of porokeratosis is still unclear. Different variants of porokeratosis (PK) have been subsequently recognized, each with its own specific properties in terms of morphology, distribution and clinical course. Linear porokeratosis is one of the variants of porokeratosis, a rare disorder of keratinization that may develop into several epidermal malignancies, squamous cell carcinoma being the most frequent among all of them. Thus, a clinical surveillance for malignancy is an imperative. We present a case of a 54-year-old man with non-healing ulcer of the lower leg caused by squamous cell carcinoma arising on long-standing linear porokeratosis. The treatment included wide excision of tumor with the reconstruction of the area. Acitretin was prescribed for linear porokeratosis treatment. The follow-up of our patient so far has shown that he does not have new malignant lesions after surgical excision.