AB006. Atypical morphologies of thymic hyperplasia on CT and MRI
Abstract

AB006. Atypical morphologies of thymic hyperplasia on CT and MRI

Tetsuro Araki1, Wei Ping Tham1,2, Arun C. Nachiappan1, Achala Donuru1, Scott A. Simpson1, Eduardo Jose Mortani Barbosa Jr1, Drew A. Torigian1

1Department of Radiology, Cardiothoracic Division, Hospital of the University of Pennsylvania, Philadelphia, USA; 2Department of Radiology, Singapore General Hospital, Singapore, Singapore

Correspondence to: Tetsuro Araki, MD, PhD. Department of Radiology, Cardiothoracic Division, Hospital of the University of Pennsylvania, 3400 Spruce St, Philadelphia, PA 19104, USA. Email: tetsuro.araki@pennmedicine.upenn.edu.

Background: Thymic hyperplasia (TH) appears as predominantly soft-tissue attenuating thymus with triangular/quadrilateral shape. There are sporadic case reports of TH with multinodular or cystic changes possibly related to Sjogren’s syndrome (SjS) and human immunodeficiency virus (HIV). No large systematic study was performed. Therefore, the purpose of this study is: (I) to investigate atypical morphologies of TH, which could be helpful in the appropriate diagnosis of TH; (II) to investigate demographical and clinical conditions relevant to the atypical morphologies.

Methods: Radiological reports of CT and MRI from January 2021 to March 2023 in our medical health network were searched by the term “thymic hyperplasia” (Montage). Two-board certified radiologists reviewed identified cases. First radiologist reviewed all CTs to confirm the presence of TH (>50% of soft-tissue attenuation) and for atypical morphologies. Second radiologist reviewed cases with atypical features to confirm, and discrepancies were resolved in consensus. Atypical features include: (I) multinodular, (II) cystic, (III) lobulated contour, (IV) calcification. MR images were also reviewed if available. Electronic medical records (EMRs) were reviewed for demographics and clinical information relevant to TH.

Results: The search yielded 1,415 reports, belonging to 954 patients. After review by radiologists, 35 cases were found with atypical morphologies. A multinodular morphology was most common (N=19), followed by cystic (N=12), lobulated (N=7), and calcification (N=5). Of those, eight cases demonstrated overlap features (multinodular/cystic, N=5; multinodular/calcification, N=1; multicystic/calcification, N=1; cystic/calcification, N=1). A total of 51% were male (18/35). Mean age was 52 years. And, 43% (N=11) were former/current smokers (mean 13.4 pack-year); 43% (N=15) of the patients had clinical conditions relevant to TH; most common autoimmune disease was rheumatoid arthritis (N=3), SjS (N=3, including one case with SSA positive), sarcoidosis (N=3), followed by systemic lupus erythematosus (SLE) (N=2), ulcerative colitis (N=1), graves disease (N=1), and steroid therapy (N=3). All three patients with SjS showed overlapping atypical morphologies of multinodular and cystic features. The 29% (10/35) had a history of malignancy, most commonly breast cancer (N=3). One patient with HIV infection demonstrated multinodular feature. However, 34% (12/35) had no clinical conditions relevant to TH. One patient with lobulated TH underwent thymectomy and was pathologically diagnosed with langerhans cell histiocytosis (LCH) involving thymic gland.

Conclusions: Atypical morphologies of TH were investigated. Multinodular and cystic features were relatively common and seen in patients with autoimmune diseases such as RA and SjS, however, also seen in patients with no relevant clinical conditions.

Keywords: Thymic hyperplasia (TH); atypical; multinodular; cystic

Acknowledgments

Funding: None.

Footnote

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://med.amegroups.com/article/view/10.21037/med-23-ab006/coif). D.A.T. reports NIH grant funding unrelated to current work and consulting fees from Quantitative Radiology Solutions LLC. D.A.T. also reports he is co-founder of Quantitative Radiology Solutions LLC. E.J.M.B. reports research support from Siemens Healthineers. T.A. reports institutional support for the meeting registration fee and travel related cost, reimbursed from the institutional professional research fund. The other authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki (as revised in 2013). The study was approved by the institutional ethics board of the University of Pennsylvania (No. 853435) and individual consent for this retrospective analysis was waived.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

doi: 10.21037/med-23-ab006
Cite this abstract as: Araki T, Tham WP, Nachiappan AC, Donuru A, Simpson SA, Barbosa EJM Jr, Torigian DA. AB006. Atypical morphologies of thymic hyperplasia on CT and MRI. Mediastinum 2023;7:AB006.

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