Hemangiomas are benign vascular tumors that result from the anomalous proliferation of vascular tissue. Thyroid hemangiomas are an exceptionally rare disease, with the majority of cases representing secondary thyroid hemangiomas attributed to fine needle aspiration (FNA) or trauma. The occurrence of primary thyroid hemangiomas worldwide remains limited.¹⁾ These hemangiomas are developmental anomalies due to the lack of angioblastic mesenchymal canal formation.²⁾ The preoperative diagnosis of thyroid hemangiomas may be challenging due to their infrequent incidence and the absence of distinct findings in patients’ medical history, physical examinations, and imaging modalities such as computed tomography (CT) and ultrasonography (US). Histological examination using a postoperative specimen is known to be the most accurate method. In this report, we present a case of a massive cavernous thyroid hemangioma that developed in the right thyroid lobe and review the relevant literature. This study, covering a patient case report, was exempted from review by the Institutional Review Board of Kangwon National University Hospital (2023-09-007).

An 83-year-old woman, suffering from odynophagia and mild dyspnea due to a large mass in the right neck, visited our clinic. The patient had underlying conditions of hypertension, diabetes, and hypothy-roidism. She has been taking levothyroxine for over 20 years, and has been under endocrinology care at our hospital for past 4 years. There was no significant family history and no reported history of head and neck trauma. FNA had not been performed in our clinic, and the patient was uncertain whether she had ever undergone a needle aspiration. On physical examination, a large goiter was observed at the inspection and palpation identified a solid, firm, mobile, and huge mass in the right thyroid region. Thyroid function test results were as follows: T4 (free thyroxine) 1.17 ng/dL, T3 (triiodothyronine) 0.92 ng/dL, TSH (thyroid-stimulating hormone) 0.159 uIU/mL, showing a slightly decreased TSH. There was a 1.7 cm increase in 2019 from 4.5 cm to 6.2 cm in 2022 on a routine thyroid US at our hospital. The mass was classified as K-TIRADS 3 with a parallel and predominantly solid composition and showed mild hypo- and iso-echogenicity throughout US (Fig. 1). Thyroid CT showed a 6.2 cm-sized heterogeneous round mass in the right thyroid region with tracheal deviation to the right with tracheal compression (Fig. 2). The patient underwent an immediate right thyroid lobectomy without FNA due to worsening obstructive symptom and a huge right thyroid mass exceeding 6.2 cm. Histologic analysis of the specimen showed dilated vessels and a thin layer of endothelial cells in the Hematoxylin & Eosin (H&E) stain. Furthermore, the brown staining of vascular endothelial cells by CD31 staining confirms the histological characteristics of cavernous hemangioma (Fig. 3). The patient remains in outpatient follow-up with no additional postoperative complications and no signs of recurrence.

Hemangiomas are benign vascular tumors of soft tissues that are characterized by the proliferation of capillaries. They may appear on skin, liver, and other any organs.³⁾ Hemangiomas are more common in infants and children, although they can develop at any age. The main types of hemangiomas include the capillary type, which is the most frequent, and the cavernous type.⁴⁾

Thyroid hemangiomas are rare, with about 30 reported cases, primarily involving cavernous hemangio-mas. The majority of thyroid hemangiomas are secondary that are caused by trauma or by invasive procedures such as FNA. After the procedure, the hemangiomas regressed spontaneously; however, abnormal vascular changes and fibroblastic proliferation lead to secondary hemangiomas.⁴⁾ Primary hemangiomas are extremely rare and occur as embryological malformation due to lack of channel formation by angioblastic mesenchymal.⁵⁾

Preoperative confirmation of primary hemangiomas and accurate identification of imaging studies are difficult because they have no obvious clinical manifesta-tions. Hence, the majority of patients receive a correct diagnosis via histopathologic examination after surgery.

In a primary cavernous hemangioma case presented by Lee et al.,⁶⁾ a large anterior neck mass was identified, without any history of invasive procedures or trauma. The mass caused obstructive symptoms and severe airway compression on chest X-ray. MRI confirmed a large left thyroid nodule without surrounding tissue invasion. FNA was not performed, and the patient underwent surgery. This case highlights the difficulty of precise preoperative diagnosis through imaging and underscores the potential for accurate diagnosis via postoperative histopathology.⁶⁾

Kumar et al.⁷⁾ proposed using Tc-99m labeled erythrocyte blood pool imaging for diagnosis of thyroid hemangioma. Shpitzer et al.⁸⁾ reported SPECT, MRI, and RBC scans for preoperative diagnosis. However, due to compression symptoms and cost constraints, these tests were not feasible for our patient.

In our case, the patient had no history of FNA during her hospital follow-up and could not recall undergoing FNA when directly questioned. The patient underwent immediate surgical treatment for obstructive symptoms such as dyspnea and dysphagia due to a large mass.

The histological features of hemangiomas are dilatation and irregularity of vessels with a thin endothelial cell layer, thrombus formation and phleboliths.⁹⁾ In addition, CD31, a transmembrane glycoprotein, is an immunological marker of vascular endothelial cells and may help to differentiate vascular tumors such as angiosarcoma and hemangioma.¹⁰⁾ Histopathologic examination of the patient showed that the endothelial cells were clearly stained brown by CD31 immuno-histochemistry. H&E staining revealed a thin layer of vascular endothelial cells, red blood cells, and fibrin in the lumen.

The thyroid cavernous hemangioma encountered is highly unusual and the preoperative differential diagnosis is quite challenging. Definitive diagnosis typically requires postoperative histopathology. In particular, in cases with compression syndrome and respiratory distress due to mass effect, immediate surgical treatment appears necessary. Further research and consideration are needed to enhance accurate preoperative examination and diagnosis for distinguishing thyroid hemangiomas.

No potential conflict of interest relevant to this article was reported.