Summary
Background. To discuss the clinical features and differences between psoriasis, melanoma, squamous cell carcinoma, and basal cell carcinoma. To evaluate whether psoralen plus ultraviolet A therapy, used in the treatment of severe psoriasis, increases the risk of developing skin cancer.
Material and methods. A systematic literature review based on reliable scientific sources was conducted, including clinical trials, meta-analyses, and case-control studies. The review analyzed the clinical, dermatoscopic, and histological features of psoriasis and malignant skin tumors, key criteria for differential diagnosis, as well as the association between psoralen and ultraviolet A therapy and skin cancer risk.
Results. Psoriasis most commonly manifests as erythematous, scaly papules and plaques on the skin, which in appearance may resemble malignant skin tumors – particularly superficial basal cell carcinoma or squamous cell carcinoma in situ. Malignant skin tumors represent one of the most common groups of oncologic diseases, and their development may be associated with severe psoriasis treatment using phototherapy with psoralen and ultraviolet A. Long-term psoralen and ultraviolet A therapy follow-up studies have shown that the risk of skin cancer increases proportionally with cumulative exposure to this therapy and remains elevated even after treatment cessation.
Conclusions. Amelanotic melanoma, squamous cell carcinoma, and basal cell carcinoma often mimic psoriasis. Any skin lesion that resembling psoriasis but displaying atypical features – such as rapid growth, changes in pigmentation, ulceration, bleeding, or asymmetry – should be urgently evaluated by performing a skin biopsy. Timely histological examination is crucial for the early diagnosis of melanoma and invasive cutaneous squamous cell carcinoma, enabling rapid initiation of treatment and improving patient’s survival prognosis. Special caution is warranted for patients who have previously undergone psoralen plus ultraviolet A therapy, as this treatment is associated with a significantly increased risk of malignant skin tumors.
