We report on a patient with a rare hepatosplenic gamma delta T-cell lymphoma (gamma delta TCL) presenting clinically with B-symptoms, hepatosplenomegaly and pancytopenia. During the initial stage of the disease the sparse malignant cells could not be detected histologically. Furthermore, their identification was obscured by massive macrophage proliferation with haemophagocytosis in the spleen. Diagnosis was established by detection of a clonal T-cell receptor (TcR) rearrangement and, retrospectively, by demonstration of rare cells expressing and aberrant T-cell phenotype. The findings in this patient emphasize that minimal neoplastic T-cell infiltrates can lead to severe clinical symptoms. Initial biopsy findings may be misinterpreted as benign. Gamma delta TCL may elaborate lymphokines that suppress haematopoiesis, leading to pancytopenia and macrophage proliferation.