Table 5 Malignancy rates for thyroid nodules with nondiagnostic fine needle aspirations according to characteristics of nondiagnostic cytopathology from April 2011 to March 2016.

From: Modified Bethesda system informing cytopathologic adequacy improves malignancy risk stratification in nodules considered benign or atypia(follicular lesion) of undetermined significance

Nondiagnostic cytology

All FNAs (Number)

Surgically resected nodules (Number)

Malignant nodules confirmed by surgery (Number)

Malignancy rate

% maximum*

% minimum†

Insufficient cellularity

189

17

10

58.8%

5.3%

Cystic fluid only

34‡

1

1

100.0%

2.9%

Obscuring blood, blood only

28§

3

2

66.7%

7.1%

Drying artifact

1‡

0

0

NA

0.0%

Mainly calcified material only

6||

1

1

100.0%

16.7%

Total

231

19

12

63.2%

5.2%

  1. Abbreviations: FNA: fine-needle aspiration.
  2. *Percentage of cases calculated from total number of resected cases in each category (maximum malignancy rate).
  3. †Percentage of cases calculated from total number of fine-needle aspirations in each category (minimum malignancy rate).
  4. ‡One of these cases was also included in the subcategory of insufficient cellularity.
  5. §Nineteen of these cases were also included in the subcategory of insufficient cellularity.
  6. ||All six of these cases were also included in the subcategory of insufficient cellularity.
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