The presence of microcalcifications is one of the representative features suggesting papillary thyroid carcinoma (PTC). Thyroid malignancy appearing solely as diffuse microcalcifications on ultrasound (US) is rare. Here, we report on a 52-year-old male patient with lymphocytic thyroiditis presenting as diffuse microcalcifications on US. This case report describes a patient who showed benign cytology twice on US-guided FNAB, and was finally found to have lymphocytic thyroiditis on core-needle biopsy. Lymphocytic thyroiditis, as well as PTC, can manifest solely as microcalcifications on US, and performance of two US-guided FNABs may be acceptable for lesions showing only microcalcifications on thyroid US.