This antibody may be used in the differential diagnosis of NK-cell lymphoma (CD56+/-) vs. other lymphomas (CD56-(+)), multiple myeloma (CD56+) vs. lympho-plasmacytic lymphoma, reactive plasmacytosis and monoclonal gammopathy of undetermined significance (MGUS) (CD56-(+)), in myeloid leukemic cells (CD56+) vs. normal myeloid cells (CD56-), non- papillary thyroid tumors (CD56+) vs. papillary thyroid carcinoma (CD56-) and schwannoma (CD56+) vs. neurofibroma (CD56-) when used in a panel of antibodies.