Thyroid frozen section: flawed but helpful.
The role of frozen section (FS) thyroid histology is controversial, some finding it helpful and others finding it inaccurate and of little assistance. The FS and subsequent permanent histology diagnosis were analysed retrospectively in 241 patients, 23 of whom were subsequently shown to have carcinoma. FS correctly identified five (22%) of these, deferred the diagnosis in three (13%) and made an incorrect benign diagnosis in 15 (65%). This impaired accuracy was attributed to the high proportion (13/23) of follicular neoplasms, which are difficult to categorize on FS. No false positive diagnoses were made in the 218 patients with benign disease. The possibility of a benign FS diagnosis being converted to malignant was 6.2%. The result of the FS affected management in that all five patients with the diagnosis of cancer underwent immediate contralateral surgery, but only seven of 18 in the negative FS group had further surgery when permanent histology demonstrated carcinoma, despite equivalent risk factors for poor prognosis in each group. This study suggests that the interpretation of FS and risk factors, in particular the tendency to interpret most follicular neoplasms as benign rather than defer decision, may be improved if pathologists and surgeons interested in thyroid disease are involved in the management of patients with thyroid nodules. Although FS remains flawed it is helpful in a small proportion of cases where it allows immediate contralateral surgery.