Solitary pulmonary MALT lymphoma presenting crystal-storing histiocytosis

Crystal-storing histiocytosis (CSH) is characterized by the accumulation of large histiocytes with intracytoplasmic crystallized immunoglobulin and is typically associated with hematological malignancies. A 69-year-old man, who had a history of left nephrectomy and chemotherapy for renal pelvic cancer six years earlier, had received a CT scan every year thereafter and a small nodule was found in the left lower lobe of his lungs two years prior to the current presentation. Because of progression of this pulmonary nodule, he underwent pulmonary lobectomy on suspicion of lung cancer. He was ultimately diagnosed as having CSH accompanied by mucosa-associated lymphoid tissue lymphoma stage IAE. In the absence of further treatment, he has been well with no recurrence of the disease for 10 months postoperatively. Because CSH could reportedly be an initial presentation of hematological malignancies, careful observation and evaluation for the presence of these blood disorders is essential.