A case of small cell lung cancer with TIF1-γ antibody-positive dermatomyositis with difficulty in treatment of pruritus

Abstract

A 72-year-old man presented to the emergency department with pruritic erythema and difficulty walking. Chest CT showed a tumorous lesion in the right lower lobe of the lung. We performed a transbronchial biopsy (TBB) and diagnosed small cell lung cancer of the lung. A skin biopsy was added and a diagnosis of dermatomyositis was made. Furthermore, the blood test for anti-TIF1-γ antibodies was positive. His dermatitis improved with tumor response to chemotherapy, but then the pruritus recurred after tumor regrowth and interfered with sleep.　Dermatomyositis is well known as paraneoplastic syndrome (PNS), and it was difficult to deal with pruritus in this case. We had judged that the itching was due to dermatomyositis, but later on, the skin findings and itching symptoms diverged, and we thought that the itching was due to paraneoplastic itch. When there is a discrepancy between skin findings and itching in a patient with a malignant tumor, it is necessary to consider the possibility that this is a symptom of paraneoplastic syndrome.