Retrospective evaluation of OUR subacute granulomatous thyroiditis (De Quervain's thyroiditis) cases

Subacute granulomatous thyroiditis (SGT) is the most common cause of pain in the thyroid gland. Since it regresses spontaneously or with medical treatment, it is not frequently encountered in routine pathology practice. The aim of our study is to reveal the histopathological features of SGT in detail, to detect accompanying benign or malignant lesions, and to assist pathologists against diagnostic pitfalls. Among the total thyroidectomy materials to delivered to the Recep Tayyip Erdoğan University Training and Research Hospital Medical Pathology Laboratory between 2009 and 2019, 48 cases diagnosed with SGT/de Quervain's thyroiditis were identified. One of the cases was excluded from our study because all the preparations were delivered to patient, and other 3 cases were excluded due to non-SGT diagnosis (sarcoidosis, Hodgkin lymphoma, and acute suppurative thyroiditis). The remaining 44 cases were analyzed in terms of characteristics and various clinicopathological data. Preoperative fine needle aspiration biopsy performed 30 of the cases (68,2%) and the results of only 1 case were compatible with SGT. Presence of confluent granulomas was the most important morphological finding observed in all cases. Other common findings were intraparenchymal fibrosis (%90,9), inflammation of peripheral nerves, involvement of neutrophils in the structure of granulomas, and atrophy of follicles (63,6%). SGT affected both lobes in 30 (68,2%) cases and only one lobe in 14 (31,8%) cases. All multinuclear giant cell types present in granulomas. Neoplasm was detected in 19 (43,2%) of cases. Of these, 6 (13,6%) were follicular adenoma, 10 (22,7%) were papillary microcarcinoma, 3 (6,8%) were papillary carcinoma. Seven (15,9%) patients had additional chronic lymphocytic thyroiditis. In our study, 44 SGT cases were examined in detail. The presence of persistent pain, multiple nodules or neoplasms puts surgical operation among the treatment options. The cause of pain in SGT may be peripheral nerve inflammation as well as pseudocapsule stretching. In the presence of prominent foci of necrosis, other possibilities must be excluded. If macroscopic changes secondary to SGT are prominent, extensive and careful sampling should be performed to avoid missing small foci of malignancy. Keywords: Subacute granulomatous thyroditis, De Quervain's thyroiditis, Confluent granulomas, Peripheral nerve inflammation, Neoplasm