Cytology of extranodal Ki-1 anaplastic large cell lymphoma

Ki-1-positive anaplastic large-cell lymphoma (ALCL) is an uncommon neoplasm which may present with extranodal as well as nodal disease. By definition, the tumor cells are immunoreactive for Ki-1 or Ber-H2 antigen (CD30). There have been few published cytologic descriptions of this lymphoma, or of its detection in extranodal sites. We describe the cytologic findings in five cases of extranodal Ki-1 lymphoma. Cytologic findings in all five cases were similar and consisted of a heterogeneous population of lymphocytes and bizarre, pleomorphic tumor cells. These cells were characterized by generous amounts of vacuolated, basophilic cytoplasm, eccentric, multilobulated nuclei with some showing "wreath-like" configurations. Some nuclei contained huge nucleoli simulating Reed-Sternberg cells. All cases showed the characteristic surface membrane and cytoplasmic paranuclear dot-like staining for CD30. Our findings indicate that fine-needle aspiration and exfoliative cytology have a useful role in the diagnosis of Ki-1 ALCL in extranodal sites. Furthermore, effusions containing anaplastic cells suspicious for lymphoma, particularly in AIDS patients, should be immunostained with antibodies to CD30.