C1: Inadequate

The designation of an aspirate as “inadequate” is sometimes subjective. The experience of the aspirator and/or the interpreter plays a decisive role. Adequacy is based on the presence of sufficient numbers of epithelial cells to provide a reliable assessment.

C1 ideal rates must be lower than 10%.

In case the lab exceeds 20% FNA’s tecnicque has to be revised.

Different reasons may lead to label a smear as inadequate:

  • Errors in sampling
  • Bad spreading
  • Poor fixation (expired fixatives, not immediate fixation)
  • Inadequate drying
  • Bad staining (under/over)
  • Poor cellularity
Errors in sampling: Sometimes diagnostic information may be present in the sample and may be included in the report. For example adipose tissue fragments could be consistent with a clinical diagnosis of lipoma. Aspirates from some lesions, (cysts, abscesses, fat necrosis and nipple discharge specimens) might not contain epithelial cells but should not be classified as inadequate.
Bad spreading: Crush artefact, when too much pressure is used during smearing or when smears are too thick when not enough pressure is applied.
Poor fixation: (expired fixatives, fixation not immediate).
Inadequate drying: when the material for air-drying dries too slowly or when the wet fixed, dries out before fixation.
Bad staining (under/over).
Poor cellularity: Remember that smears from some malignant lesions may contain only few atypical elements because of the desmoplastic reaction such as that found in some lobular carcinomas. It is always important to keep in mind that any case with few atypical elements should not be considered as inadequate.