Gross phenotype of T-LBL and GD in the proband and her affected sister. (A) Biopsy of the mediastinal mass showing a T-LBL with diffuse infiltration of the soft tissues by a population of monomorphic lymphoid cells with hyperchromatic nuclei and scant cytoplasm. Immunophenotyping revealed the tumor cells to be positive for CD34 and negative for CD4 and CD8. (B) Chest radiograph of patient 1 demonstrating mediastinal mass at time of initial diagnosis of T-LBL. (C) BM biopsy performed several months later showing the presence of many large macrophages with pale eosinophilic cytoplasm and typical wrinkled tissue paper appearance typical of GD. (D) Electron microscopy performed on the BM shows many Gaucher cells with cytoplasmic striations that represent abundant tubular bodies. (E) Biopsy of the mediastinal mass in patient 2 showing features of T-LBL. (F) BM biopsy from patient 2 showing the presence of many Gaucher cells similar to her sibling.