Primary malignant lymphoma arising in the pleura without preceding long-standing pyothorax.

We report a very rare case of primary malignant lymphoma arising in the pleura with no history of persistent pyothorax. A 72-year-old male was hospitalized with dyspnea on effort and chest CT demonstrated a mass along the right chest wall. Right thoracotomy with complete en bloc resection of the pleural tumor was performed. Immunohistochemical examination of the pleural tumor showed that the histology was marginal zone B-cell malignant lymphoma. We considered that this tumor had originated from the soft tissue in the chest wall based on radiographical and surgical findings. As diagnosis and treatment of pleural malignant lymphoma seems to have been difficult in most cases reported in the literature, it is thought that early active and accurate biopsy with large-bore needles, or, if possible, surgical incision for early diagnosis and aggressive surgery to achieve complete resection combined with radiation therapy and/or chemotherapy would be very important for a good prognosis.