Are clonal T-cell large granular lymphocytes to blame for unexplained haematological abnormalities?

Abnormalities diagnosed on routine blood work, such as mild neutropenia, anaemia, thrombocytopenia and relative lymphocytosis, often have obscure aetiologies. A series of 30 patients were evaluated for various unexplained haematological abnormalities between 1997 and 2005, and found to have circulating monoclonal T-cell large granular lymphocytes (T-LGL). These patients fit the diagnosis of T-cell clonopathy of unknown significance (TCUS), which may represent a clinical spectrum of clonal T-LGL proliferation. Our patients were characterised by a complete absence of severe neutropenia (<0.5 x 10(9)/l), absence of recurrent neutropenic infection (0%), negative rheumatoid serology (0%) and a low incidence of constitutional symptoms (20%). This overall asymptomatic clinical presentation appeared to be different from other previously reported series of TCUS or T-LGL leukaemia who typically had symptomatology and required treatment. Our series of 30 patients represented the benign end of the spectrum of clonal T-LGL proliferation, and might reflect diagnosis at earlier stages of the condition relative to other reported series. TCUS may be a heterogeneous and under-diagnosed condition. This study further broadens our understanding of the clinical and laboratory manifestations of indolent clonal T-cell proliferation, and raises our awareness of this condition. We suggest that TCUS should be considered in the diagnostic evaluation of unexplained haematological problems.