Anaplastic Lymphoma Kinase Immunocytochemistry in Fine Needle Aspiration Diagnosis of Anaplastic Large-cell Lymphoma.

Background: Anaplastic large-cell lymphoma (ALCL) is a rare subtype of non-Hodgkin's lymphoma (NHL) characterized by the presence of unusual giant cells. It is a CD30+lymphoma of T-cells lineage, which shows anaplastic lymphoma kinase-nucleophosmin (ALK-NPM) rearrangement. ALCL on fine needle aspiration cytology (FNAC) shows unusually large and bizarre tumor cells.

Methods: All aspirates seen over a 6-year period from November 2009 to November 2015 in which a diagnosis of ALCL or Hodgkin's lymphoma (HL) with bizarre giant cells were suspected on cytomorphology were prospectively selected. Twenty such aspirates were subjected to CD-30 and ALK-1 immunocytochemistry (ICC). Subsequent biopsy was available in all cases.

Results: Out of 20 cases, seven cases, suspected to be ALCL on FNAC, were confirmed on biopsy. ALK-1 was positive in both cytology and biopsy of 6/7 of these. Two cases suspected to be ALCL on cytomorphology were HL (1) and diffuse large B-cell lymphoma (DLBCL) (1) on biopsy, both of which were ALK-1 negative on cytology. Eight cases of HL and three cases of large-cell NHL, which were all ALK negative on cytology, were confirmed on biopsy.

Conclusions: ICC for ALK and CD30 is useful in aspiration cytodiagnosis of ALCL. One CD30 positive DLBCL and one ALK negative ALCL showed concordant results of ICC on cytology and histology.