In Japan, most malignant lymphomas of the chest wall are associated with pyothorax, with poor prognosis being reported.
An 81-year-old man developed pleurisy 4 years ago and low-grade oral steroid therapy (30mg/day to 5mg/day) was started for suspected collagen disease. While suffering from the collagen disease, he fulfilled the criteria for systemic lupus erythematosus (SLE). His disease went into remission, so steroid therapy was stopped after administration for 3 years and 6 months. Six months after cessation of steroids, he was admitted to our hospital complaining of high fever, and a right chest wall tumor was detected. Echo-guided biopsy revealed diffuse large B-cell lymphoma of the chest wall. The patient and his family did not wish for aggressive treatment, so oral steroids at 5mg/day were restarted and the chest wall tumor disappeared within 1 month. This is a very rare case of regression of malignant SLE-associated lymphoma achieved by small amounts of steroid therapy.