Primary Adenoid Cystic Carcinoma of the Upper Anterior Mediastinum Mimicking a Thyroid Tumor: A Case Report and Review of Literature

Abstract

Primary adenoid cystic carcinoma (ACC) of the upper anterior mediastinum mimicking a thyroid tumor has rarely been seen in clinical practice and lacks a standard of care therapy. Here, we report a 47-year old female patient with an ACC originated from the upper anterior mediastinum presenting as a thyroid gland tumor. The patient received gross surgical resection of the tumor and underwent post-surgical chemotherapy and radiotherapy. The patient was free from local recurrence 3-years following initial treatment, but developed multiple lung metastases. She remains under clinical observation without discomfort and is still followed as an outpatient. Here, we also summarized recent reports of similar cases with hope to provide some experience for future clinical practice.

Keywords: adenoid cystic carcinoma; case report; diagnosis and treatment; literature review; thyroid neoplasms.

Figure 1

Cervical-thoracic CT scans of the patient. Representative axial images of the disease before surgery, post-surgery/before radiotherapy, and 2-years after radiotherapy were shown. The red arrow highlighted the tumor and post-treatment changes in the tumor area.

Figure 2

Pathological features of the tumor. HE staining image indicated a cribriform ACC. Immunohistochemical staining images showed positive expression of Ki-67, SMA, EMA, CK8-18, CK5-6, p63, and CD117, which supported a diagnosis of ACC. ACC, adenoid cystic carcinoma; SMA, smooth muscle actin; EMA, epithelial membrane antigen; CK, cytokeratin; CD, cluster of differentiation.

Figure 3

Dose distribution of post-surgical radiotherapy. Representative axial, sagittal, and coronal images of dose distribution were shown. Areas with dose coverage of over 54 Gy were presented.