The appearance of multiple, extrapulmonary, pleural-based nodules and masses on chest radiography and CT is nonspecific. Differential considerations include pleural metastases (lung, breast, GI tract, pancreas, kidneys, and ovaries), lymphoma, asbestos-related pleural plaques, mesothelioma, and invasive thymoma by contiguous extension. A history of thoracoabdominal trauma, splenectomy, and findings of left-sided, extrapulmonary, pleural-based nodule(s) should indicate the diagnosis of thoracic splenosis. A radiologic diagnosis can be confirmed by either a 99mTc sulfur colloid, 111I-labeled platelet, or 99mTc heat-damaged erythrocyte study, which all result in increased uptake of the radioactive isotope in the ectopic splenic tissue. Including our case, only 10 of the 30 cases reported in the English-language literature have been confirmed by nuclear scintigraphy,6,10–11,13 with the remainder confirmed at biopsy, surgery, or autopsy. However, transthoracic fine-needle aspiration cytology of thoracic splenosis may create pitfalls in diagnostic interpretation when populations of small and medium-sized lymphocytes may erroneously suggest a lymphoproliferative disorder.12 Radiologic diagnosis avoids biopsy or operation and preserves the patient’s remaining splenic tissue. No specific cause for the patient’s symptoms was found, and the patient will continue to be followed up.