A case report of T-LGL leukemia-associated pure red cell aplasia harboring STAT3, TNFAIP3, and KMT2D mutation.

Background: T-large granular lymphocyte (T-LGL) leukemia is a rare clonal lymphoproliferative disorder, which has a favorable prognosis. There are different complications between Asian and Western patients diagnosed with LGL leukemia. In Asians, pure red cell aplasia (PRCA) is the most common hematological compatible clinical feature of LGL leukemia, whereas in Western patients, rheumatoid arthritis and neutropenia are more commonly seen. Herein, a rare case of T-LGL leukemia associated PRCA was reported.

Case Description: A 72-year-old man, presenting with anemia and leukopenia, was admitted to hospital. The bone marrow (BM) smear revealed that erythroid series were suppressed with only 4%, mature lymphocytes constituting up to 23% of the marrow cells. The results of T-cell receptor (TCR) arrangement revealed mutations in the and genes. Further, mutation (p. [D661Y; N664T] and p.N647I), mutation (p.L48fs), and mutation (p.E5291K) were confirmed. The patient was diagnosed with CD8+ T-LGL leukemia-associated PRCA, harboring and mutation. The BM smear, immunophenotype, gene rearrangement and karyotype were consistent with those of the first diagnosis. Cyclosporine A (CyA) based regimens were effective, even in a cessation of discontinued treatment. The patient refused BM-related examinations and has remained in hematological complete remission (CR) until the time of writing (at least 3 years).

Conclusions: The administration of CyA yielded a CR in this case. However, the standard therapy for T-LGL leukemia-associated PRCA is not clear, and more prospective studies are needed to ascertain the underlying mechanism of pathogenesis.