CORRELATION OF LIGHT-MICROSCOPIC, IMMUNOCYTOCHEMICAL AND ULTRASTRUCTURAL CYTOMORPHOLOGY OF ANAPLASTIC LARGE-CELL KI-1 LYMPHOMA, AN ACTIVATED LYMPHOCYTE PHENOTYPE - A CASE-REPORT

BACKGROUND: Anaplastic large cell Ki-1 lymphoma has been proposed to b e a neoplasm of activated lymphocytes, mostly of T-cell origin. CASE: A previously healthy 12-year-old boy presented with a two-month histor y of a rapidly growing hard palate mass that involved the nasal cartil age and extended to the floor of the right orbit. By light microscopy (LM) the aspirates were very cellular, containing single, pleomorphic cells and occasional cellular aggregates. The cells showed distinct po larity, with the large, anaplastic nucleus at one end and the tapering cytoplasm, including a prominent paranuclear halo (or ''hof''), at th e other end (''hand mirror'' appearance). The cytoplasmic border showe d prominent ruffling, concentrated at the two poles of the cells and c orresponding to the areas of the protopod and uropod. Immunocytochemic ally (ICC) the cells were positive for Ki-1, epithelial membrane antig en and UCHL-1, all of which showed both membrane positivity along with Golgi area staining. LCA showed variable membrane staining. Ultrastru cturally (electron microscopy [EM]) the polarity was recapitulated, wi th an eccentric, horseshoe-shaped nucleus partially enclosing a promin ent Golgi complex with associated centrosomes and asymmetric plasma me mbrane ruffling. CONCLUSION: All three levels of examination (LM, ICC and EM) revealed tumor cell features corresponding to the phenotype of the activated lymphocyte. These features are characteristic, thus all owing the diagnosis of Ki-1 anaplastic lymphoma by fine needle aspirat ion cytology.