College of American Pathologists
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August 2003
Special Section

Defining adequacy in nongynecologic cytology

Thyroid FNA specimen adequacy guidelines

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Dina R. Mody, MD

The Bethesda System of cervicovaginal cytology reporting addresses adequacy issues in gynecologic cytology. These criteria were modified further in Bethesda 2001 for conventional and liquid-based specimens.1 Unfortunately, no such reporting system exists for nongynecologic cytology. In 1996, the Bethesda conference on breast cytology attempted to develop adequacy guidelines and a reporting system.2 However, unlike the cervicovaginal cytology reporting system, it has not been universally accepted.

The CAP Cytopathology Committee has a simplified reporting system for its peer comparison program in nongynecologic cytology. The general categories are positive, negative, suspicious, and unsatisfactory. Although this system works in most instances, it has to be modified occasionally for certain sites or cases because a one-size-fits-all approach does not always work in nongynecologic cytology. The issue of adequacy is also difficult because the criteria vary from one site to another. Even within a given site, what is considered adequate for one specimen type is not necessarily so for another.

An example is respiratory specimens such as bronchial washings versus bronchoalveolar lavage (BAL). Finding a large number of free alveolar macrophages (FAMs) (about 93 percent ± five percent) is considered adequate for BALs, whereas many ciliated respiratory cells and few FAMs are considered inadequate for a BAL but adequate for a bronchial washing. However, a lung FNA with free alveolar macrophages and ciliated respiratory cells in a case with a lung mass, albeit adequate, is not diagnostic. Although the needle is clearly in the lung, it has not sampled "it," whatever that "it" is. While a diagnostic specimen is always adequate, the reverse is not necessarily the case.

For most FNA specimens, an adequate sample is one that explains the clinical scenario or lesion. Obscuring factors such as blood, inflammation, distortion, poor fixation, and necrosis involving the majority of specimen/slides can contribute to an unsatisfactory FNA. With this general principle in mind, most fine-needle aspirations can be interpreted. Listed below are criteria for adequacy in selected areas of nongynecologic cytology based on the published literature.

    FNA breast (solid nodules) (breast Bethesda)2 adequacy
  • One that resolves the problem presented by the lesion (no specific requirement for minimum number of ductal cells).
  • Adequacy determined by:
    1. Aspirator: cytologic findings consistent with clinical impression and knowledge that lesion has been adequately sampled.
    2. Pathologist: no significant distortion or artifacts hindering interpretation.
  • Specimen description should include quantity of epithelial cells.
    1. Few (occasional clusters).
    2. Moderate (clusters easy to find).
    3. Abundant (epithelial cells in almost every field).
  • Mention other cellular components.
  • Labs can choose their own cell counts (but no national standard).
    FNA breast (cyst)2 adequacy
  • If contents are watery/green and there is no residual mass, fluid may be examined or discarded at discretion of aspirator.
  • If residual mass, reaspirate/ biopsy.
  • If bloody (nontraumatic), careful clinical and cytologic evaluation is warranted.

For unsatisfactory breast cytology in solid masses, state the reason, that is, scant cellularity, air-drying or distortion, obscuring blood or inflammation, or other factors.2

Other definitions and opinions on breast cytology adequacy are available in the references.3-8

    Thyroid adequacy
  • Six to eight groups of well-preserved follicular cells (10 or more cells per group).9
  • Six groups of follicular cells on at least two slides from separate passes.10, 11
  • Minimum of 10 clusters of follicular cells (20 cells/cluster).12
  • In cystic lesions, aspirate should be clinically representative. Abundant watery colloid and histiocytes but few or no follicular cells in a large cyst can be interpreted as consistent with benign colloid goiter/ cyst, but comment that evaluation is limited by absent or scant follicular cells.3 Cystic papillary carcinomas rapidly recur after aspiration; hence, followup by clinician is important. If residual mass after emptying cyst, then reaspirate mass.13
  • If malignant cells are present, specimen is satisfactory/adequate. If only a few malignant cells, then specimen may be interpreted as "suspicious."13

For the Papanicolaou Society guidelines for thyroid FNA specimen adequacy,13 see the box above.

    Respiratory, adequacy
  • Sputum. Easily identifiable alveolar macrophages and enough specimen to prepare a minimum of two smears/ slides.14
  • Bronchial wash and brush. Specimen is adequate when cells or agents diagnostic of a pathologic process are present. Absent the diagnostic cells, many well-preserved, optimally stained, ciliated bronchial epithelial cells and few macrophages should be present to qualify for an adequate specimen. Heavy contamination or obscuring oral cellular and other material qualifies as unsatisfactory.
  • Bronchoalveolar lavage (BAL). Adequate if it demonstrates a specific pathologic process. Otherwise it should have numerous alveolar macrophages (93 percent ± five percent) and few lymphocytes. Occasional neutrophils and rare ciliated / squamous cells.
    Unsatisfactory BAL14, 15
  • Paucity of alveolar macrophages (<10/hpf) or <25/hpf with exudate/blood or artifacts.
  • Too many ciliated or squamous cells (more than five percent).
  • Mucopurulent exudate (polys), excessive blood.
  • Degenerated cells and lab artifacts.
    Respiratory FNAs
  • Cells that explain the radiographic and clinical presentation.
  • Alveolar macrophages, mesothelial cells, respiratory epithelial cells.
  • Blood, low cellularity, tracheobronchial secretions, air-drying, and so forth, in absence of diagnostic cells contribute to an unsatisfactory designation.
  • Normal voided urine has few urothelial cells in a clean background and no leukocytes.
  • Rare superficial squamous cells of urethral origin in men.
  • Women have squamous cells from trigone.
  • Sparsely cellular urine in a symptomatic patient is unsatisfactory.
  • Large number of inflammatory cells, blood, crystals, debris, bacteria, or yeast contaminants may also render the urine unsatisfactory by obscuring the diagnostic cells.
    Gastrointestinal tract
  • An adequate sample is one that explains the clinical/endoscopic findings.
  • Absent the diagnosis, an adequate brushing is one with six to 10 well-visualized and preserved epithelial cells (at least six cells per cluster).
  • Too few cells, poor preservation, degenerated cells, obscuring inflammation, blood, or necrosis render the specimen unsatisfactory.

Adequacy is a challenging issue in nongynecologic cytology with medicolegal implications. Perhaps it is time for those of us in the cytology community to put our collective heads together and reach a consensus. Of course, what is adequate but nondiagnostic is another topic that perhaps needs to be dealt with more on a case-by-case basis as it is in surgical pathology.


  1. Solomon D, Davey D, Kurman R, et al. The 2001 Bethesda System: terminology for reporting results of cervical cytology. JAMA. 2002;287:2114-2119.
  2. Uniform approach to breast fine needle aspiration biopsy: a synopsis. Acta Cytol. 1996;40:1120-1126.
  3. Suen K, Kline T, Nguyen G. In: Critical Issues in Cytopathology. Adequacy of non gynecologic cell samples. New York: Igaku-Shoin; 1995: 68-82.
  4. Kline TS. Adequacy and aspirates from the breast: a philosophical approach. Diagn Cytopathol. 1995;13: 470-472.
  5. Sneige N, Staerkel GA, Caraway NP, et al. A plea for uniform terminology and reporting of breast fine needle aspirates: the M.D. Anderson Cancer Center proposal. Acta Cytol. 1994;38: 971-972.
  6. Boerner S, Sneige N. Specimen adequacy and false negative diagnosis rate in FNAs of palpable breast masses. Cancer. 1998;84:344-348.
  7. Abele JS, Wagner LT, Miller TR. Fine needle aspiration of the breast: cell counts as an illusion of adequacy. A clinical cytopathologist's point of view. Cancer. 1998;84:319-323.
  8. Moriarty AT: Fine needle biopsy of the breast: When is enough enough? Diagn Cytopathol. 1995;13:373-374.
  9. Goellner JR, Gharib H, Grant CS, et al. Fine needle aspiration cytology of the thyroid. Acta Cytol. 1987;31:587-590.
  10. Kini SR. Thyroid. Guides to Clinical Aspiration Biopsy. New York: Igaku-Shoin; 1987.
  11. Hamburger JI, Husain M, Nishiyama R, et al. Increasing the accuracy of fine needle biopsy of thyroid nodules. Arch Pathol Lab Med. 1989;113: 1035-1041.
  12. Nguyen G-K, Ginsberg J, Crockford PM. Fine needle aspiration biopsy cytology of the thyroid. Its value and limitations in the diagnosis and management of solitary thyroid nodules. Pathol Annu. 1991;26:63-91.
  13. Guidelines of the Papanicolaou Society of Cytopathology for the examination of fine needle aspiration specimens from thyroid nodules. Diagn Cytopathol. 1996;15:84-89.
  14. Guidelines of the Papanicolaou Society of Cytopathology for the examination of cytologic specimens obtained from the respiratory tract. Modern Pathol. 1999;12: 427-436.
  15. Chamberlain DW, Braude AC, Rebuck AS. A critical evaluation of bronchoalveolar lavage: criteria for identifying unsatisfactory specimens. Acta Cytol. 1987;31:599-605.

Dr. Mody, chair of the CAPCytopathology Committee, is professor of pathology, Baylor College of Medicine, Houston, and director of cytopathology at Baylor and Methodist Hospital, Houston.