The association of papillary thyroid cancer with microcalcification in thyroidnodules with indeterminate cytology based on fine-needle aspiration biopsy

Microcalcifications are generally accepted as highly specific for thyroid malignancy, especially for papillary thyroid carcinoma (PTC). The aim of this study was to determine the significance of microcalcification within nodules that were classified as being of “indeterminate cytology” (IC) according to fine-needle aspiration biopsy.

Patients who underwent thyroidectomy between January 2010 and 2013 were included in the study. Nodules identified as “atypia/follicular lesion of undetermined significance", "follicular neoplasm/suspicious for follicular neoplasm", or "suspicious for malignancy" were categorized as IC. Patients were subcategorized depending on the presence of microcalcification (Group 1) or its absence (Group 2). The relationship between microcalcification and PTC was evaluated in the IC group retrospectively.

Indeterminate cytology was detected in 135 (28.5%) of 473 patients. Microcalcification was detected in 27 (20%) of 135 nodules and classified as Group 1, while the remaining 108 (80%) patients were classified as Group 2. According to the final pathology results, PTC was diagnosed in 13 of 27 (48.1%) patients in Group 1 and 29 of 108 (26.8%) patients in Group 2. A statistically significant relation between microcalcification and malignancy was determined in the IC group (P < 0.05).

Surgery might be considered primarily for patients harboring nodule(s) with IC accompanied by microcalcification due to increased risk of PTC.