Acquired Pure Red Cell Aplasia Secondary to Indolent Mature T-cell Lymphoid Malignancy.

Pure red cell aplasia (PRCA) is a rare hematologic disorder characterized by a marked decrease in reticulocytes and erythroid cells. For a long time up until today, PRCA has been clinically divided into idiopathic, thymoma-associated, and T-large granular lymphocytic leukemia (T-LGLL)-associated acquired PRCA (aPRCA). We herein report the case of a 90-year-old woman diagnosed with aPRCA secondary to an indolent mature T-cell malignancy atypical for T-LGLL. No apparent large granular lymphocytes were detected, tests for cytotoxic antigens, including granzyme B and perforin, were negative, and no STAT3 mutations were detected. Therefore, a careful evaluation of the underlying disease accompanied by aPRCA is required.