Context.—Lymphomas have traditionally been diagnosed on excisional biopsies of lymph nodes in order to evaluate tissue architecture and cytomorphology. Recent lymphoma classification schemes emphasize immunophenotypic, genetic, and molecular aspects in addition to morphology as diagnostic features. Core needle biopsies are increasingly being used to obtain tissue for diagnosis in patients with lymphadenopathy and a clinical suspicion of lymphoma. These procedures are rapid, minimally invasive, well tolerated, and may provide some architectural framework (unlike fine-needle aspirations), as well as material for ancillary studies. Objective.—To explore the accuracy, utility, and cost-effectiveness of this technique. Design.—Core needle biopsies of 101 consecutive patients from 2 large community hospitals who were suspected of having primary or recurrent lymphomas were retrospectively reviewed. All patients had hematoxylin-eosin–stained sections of needle cores. Specimens morphologically suspicious for lymphoma were subjected to ancillary studies, including immunohistochemistry, flow cytometry, and/or molecular studies. Core needle biopsy diagnoses were correlated with subsequent excisional biopsies, if performed. Results.—Core needle biopsies established a definitive pathologic diagnosis for the vast majority of cases. A diagnosis was considered sufficient to begin treatment for primary and recurrent lymphomas in most cases. Compared with an open biopsy, there is a cost savings of greater than 75%. Conclusion.—The accuracy of this technique, along with the cost savings and decreased morbidity, suggest that this method may be used safely and reliably as a first-line diagnostic technique.

Context.—The uses of monoclonal antibodies via immunochemistry have been reported frequently within the literature using various methodologies with applications to cytology specimens. The direct application of immunochemistry to cytology may have a variety of pitfalls that the general pathologist familiar with its application to histology may be unaware of when applying it prospectively to patient specimens. Objective.—To review common pitfalls when applying immunochemistry to cytology specimens and to suggest approaches to the more common differential dilemmas that apply to a variety of cytology specimens that could be seen in a general pathology practice. Data Sources.—The authors' own experiences of applying immunochemistry to cytopathology specimens within an academic setting along with supportive data from the literature. Conclusions.—Immunochemistry can be used to increase the predictability of a cytology diagnosis if care is taken with the cytology sample preparation methodology and there is judicious use of select monoclonal antibody panels to support a specific cytology diagnosis. Up-to-date evidence-based antibody databases should be used when selecting antibody panels.

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