Bazex Syndrome in Lung Squamous Cell Carcinoma: High Expression of Epidermal Growth Factor Receptor in Lesional Keratinocytes with Th2 Immune Shift

An 82-year-old Japanese man was referred for detailed examination of hyperkeratotic erythematous plaques on his palms and soles for 6 months. Two weeks before his first visit, he had undergone lung lobectomy for right lung squamous cell carcinoma (SCC). Laboratory findings showed elevations of eosinophil counts, serum IgE, thymus and activation-regulated chemokine, SCC antigen, and soluble interleukin-2 receptor levels. Histological results of a skin biopsy involving the left palm showed psoriasiform dermatitis. Before lung lobectomy, the hyperkeratotic erythematous plaques on the palms and soles and the erythemas on the trunk and extremities were difficult to treat with topical steroids. After lobectomy, the skin symptoms dramatically and rapidly subsided with topical steroids. Therefore, we diagnosed Bazex syndrome (BS), also known as acrokeratosis paraneoplastica, as a paraneoplastic cutaneous disease in lung SCC. The mild eosinophilia subsided and levels of SCC antigen, IgE, and soluble interleukin-2 receptor were reduced. BS is a paraneoplastic cutaneous disease characterized by acral psoriasiform lesions associated with an underlying neoplasm. In a previous report, a shift to the Th2 immune condition was found in patients with non-small cell lung cancer, as shown in our patient. Epidermal growth factor receptor (EGFR) is also known as tumor growth factor-α receptor; it is increased in psoriatic keratinocytes. In our case, EGFR expression increased in lesional keratinocytes 2 weeks after surgery and decreased 4 weeks after surgery. We speculate that a shift to Th2 immune reactions in lung SCC may be the pathogenesis of BS, whereby lesional keratinocytes highly express EGFR in parallel with disease activity.