Chemotherapy-Induced Thymus Hyperplasia Can Mimic Tumor Recurrence

Abstract

A 47-year woman presented with an 8 cm breast mass.Histology and staging indicated a stage III breast cancer. She received eight cycles of neoadjuvant chemotherapy (Adriamycin and cyclophosphamide followed by paclitaxel) and then underwent a modified radical mastectomy. Upon recovery from surgery, she underwent a computed tomography scan of the chest as part of radiation therapy treatment planning. This study showed interval development of an anterior mediastinal mass ( Fig. 1) that was not present on a previous scan done as part of her initial staging (Fig. 2). To exclude progression of her malignancy, an excisional biopsy was done that revealed thymus hyperplasia (Fig. 3).Thymus hyperplasia associated with chemotherapy was first described in children and represents a form of "rebound phenomenon" occurring in a number of conditions, including recovery from severe stress situations and after administration of corticosteroids or chemotherapy. It is rarely seen in adults and therefore can be easily confused with cancer progression. The evaluation of a postchemotherapy anterior mediastinal mass ranges from close observation to excisional biopsy. If the diagnosis of thymus hyperplasia is entertained, administration of short-term steroids will reduce the size of the thymus and eliminate unnecessary surgery. Occasionally histologic confirmation may be required. Empiric antineoplastic therapy is not indicated. Figure 1. Computed tomography scan of the thorax shows thymic enlargement in the anterior mediastinum.Figure 2. Computed tomography scan of the thorax at initial staging shows no mass in the anterior mediastinum.

[18F]FDG positron emission tomography/computed tomography and multidetector computed tomography roles in thymic lesion treatment planning

“…2). Both situations may increase thymic uptake as reported by Tatebe et al [3] and Halaweh et al [27]. Had the physicians been aware of the clinical history of these two patients, exam interpretation could have been Several studies reported that semi-quantitative analysis is not reliable to differentiate thymic lesions nature, while recently Sung et al [23] reported that SUV is correlated with malignant grade of thymic lesions.…”

“…Large size of the tumor, multifocal calcifications and necrotic foci are characteristics more commonly seen with invasive thymomas [26,27].…”