Fine‐needle aspiration cytology of primary large‐cell lymphoma of the mediastinum: Cytomorphologic Findings With Potential Pitfalls in Diagnosis

We report the fine‐needle aspiration (FNA) cytomorphologic features of six cases of primary mediastinal large‐cell lymphoma with sclerosis. The series consisted of three men and three women with a median age of 36 yr. All the patients presented with a large anterior or superior mediastinal mass with no evidence of peripheral lymphadenopathy or hepatosplenomegaly. Two of the cases showed typical findings of lymphoma, characterized by hypercellular specimens with numerous individually scattered markedly atypical lymphoid cells present, demonstrating nuclear irregularity with the presence of nucleoli and surrounding scant to slight amount of cytoplasm. Numerous lymphoglandular bodies were seen in the background. Both cases were correctly diagnosed as representing non‐Hodgkin's large‐cell lymphomas. Two other cases had slight cellularity with the presence of a few scattered atypical lymphoid cells. Although a definite diagnosis was not rendered in either case, the possibility of malignant lymphoma was considered. Two other cases consisted predominantly of microtissue fragments with some associated scattered individual atypical cells. Within the microtissue fragments, the cells were distorted with a tendency to elongate and spindle in a prominent fibrous matrix. Our experience demonstrates that FNA cytology of primary mediastinal diffuse large cell lymphoma with sclerosis can be challenging, with a potential for a false‐negative diagnosis due to limited cellularity secondary to the sclerosis or a misdiagnosis as a spindle cell neoplasm due to distortion of these cells by the fibrous matrix. To the best of our knowledge, we believe this is the first FNA series of primary mediastinal diffuse large cell lymphoma with sclerosis.