This cytospin is from a patient who presented in respiratory distress and was found to have a large mediastinal mass and large bilateral pleural effusions.
The lymphoid cells in this image are large and immature in appearance. These lymphocytes were initially believed to be consistent with lymphoma cells but, after immunophenotyping, were found to be reactive T-cells instead of lymphoma cells.
The three larger cells in the image look similar. The two larger cells indicated by the red arrows are just macrophages. The large cell indicated by the blue arrow is a malignant cell. The malignant cell has a large nucleus with open chromatin and a prominent nucleoli. The cytoplasm is also basophilic, and the vacuoles are atypical. These are not the typical round vacuoles seen in macrophages; these vacuoles are more elongated.
The diagnosis of ALCL was confirmed when cytogenetic testing proved positive for the specific translocation, t(2;5), that defines this lymphoma.