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\begin{document}

\title{Ectopic thyroid gland - a differential diagnosis of a submandibular mass}



\author[1]{Henrique Messias}%
\author[2]{Maria Luisa Sequeira}%
\author[3]{Miguel Vilares}%
\author[3]{Sandra Bitoque}%
\author[2]{Pedro Gomes}%
\affil[1]{University of Edinburgh Division of Clinical and Surgical Sciences}%
\affil[2]{Francisco Gentil Portuguese Institute for Oncology of Lisbon}%
\affil[3]{Instituto Portugues de Oncologia de Lisboa Francisco Gentil EPE}%


\vspace{-1em}



  
  \date{May 21, 2024}


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\selectlanguage{english}
\begin{abstract}
A 41-year-old female patient was referred to the head and neck surgery
department because of a large midline submandibular mass that was
diagnostic for functioning thyroid tissue in a totally ectopic location.%
\end{abstract}%



\sloppy


\textbf{TITLE PAGE -- \emph{CASE IMAGES}}

\emph{Ectopic thyroid gland -- a differential diagnosis of a
submandibular mass}

Authors: Henrique Messias, MD MSc\textsuperscript{1,2,}*; Maria Lu\selectlanguage{ngerman}ísa
Sequeira, MD\textsuperscript{1}; Miguel Vilares, MD\textsuperscript{1};
Sandra Bitoque, MD\textsuperscript{1}; Pedro Gomes,
MD\textsuperscript{1}

Affiliations:

\textsuperscript{1} Head and Neck Surgery department, Portuguese
Institute of Oncology Francisco Gentil, Lisbon, Portugal.

\textsuperscript{2} Division of Health Sciences, University of
Edinburgh, United Kingdom.

* Corresponding author:

Henrique Messias, MD MSc

Head and Neck Surgery department, Portuguese Institute of Oncology of
Lisbon Francisco Gentil,

Rua Professor Lima Basto, 1099-023 Lisboa, Portugal

Tel: +351913858593, E-mail: v1hmessi@ed.ac.uk

\textbf{Ethical Statement}

Written informed consent was obtained from the patient to publish this
report in accordance with the journal's patient consent policy.

\textbf{Data Availability Statement}

The authors declare that all data supporting the findings of this study
are available within the article and its supplementary information
files.

\textbf{Conflict of Interest}

The authors declare to have no conflicts of interest in connection with
this scientific work.

\textbf{Abbreviations:} CT, computerized tomography; FNAC, fine needle
aspiration cytology; TSH, thyroid stimulating hormone.

\textbf{ABSTRACT}

A 41-year-old female patient was referred to the head and neck surgery
department because of a large midline submandibular mass that was
diagnostic for functioning thyroid tissue in a totally ectopic location.

\textbf{KEY CLINICAL MESSAGE}

This rare diagnosis highlights the importance of anatomical and
embryological knowledge in the differential diagnosis of neck masses.



\textbf{ACCOMPANYING TEXT}

A 41-year-old female patient was referred to the department of head and
neck surgery due to a large submandibular midline mass that had been
present since childhood but had progressively increased in the three
months prior to referral. \textbf{{[}Image 1{]}} CT scan of the
neck\textbf{{[}Image 2{]}} described the lack of eutopic location of the
thyroid gland, scintigraphy indicated that functional thyroid tissue was
located only in the submandibular mass, and FNAC was diagnostic for
benign thyroid tissue. Thyroid function blood tests (TSH and thyroxine)
were normal. A multidisciplinary team of physicians decided for surgical
resection, which included the hyoid bone and adjacent muscles due to the
proximity of the submandibular mass. \textbf{{[}Images 3 and 4{]}} The
anatomopathological evaluation confirmed thyroid tissue without any
malignant characteristics present.

Ectopic location of the thyroid gland is a rare event, with a reported
prevalence of 1:100,000 to 1:300,000 in the general population. {[}1{]}
This anomaly is due to the embryological development of the thyroid
gland from the base of the tongue to its normal eutopic location in the
lower third of the neck, just anterior to the trachea. {[}1{]} Ectopic
location in the trachea, thorax, and abdomen has also been reported.
{[}2{]}

Submandibular neck masses present a broad differential diagnosis, with
emphasis on neck malignant disease that must be excluded. {[}2{]}
Although malignancy is rare in ectopic thyroid tissue, this diagnosis
should be kept in mind whenever a patient presents with a neck mass.
{[}1-3{]} Also, as it is the case in more frequent midline neck masses,
such as in thyroglossal duct cysts, it is important in the diagnostic
workup to exclude the presence of ectopic thyroid tissue, which may
represent the patient's only functioning thyroid. {[}3{]}

\textbf{REFERENCES}

\begin{enumerate}
\tightlist
\item
  Noussios G, Anagnostis P, Goulis DG, et al. Ectopic thyroid tissue:
  anatomical, clinical, and surgical implications of a rare entity,
  European Journal of Endocrinology, 2011.
\item
  Guerra G, Cinelli M, Mesolella M, et al. Morphological, diagnostic and
  surgical features of ectopic thyroid gland: A review of literature,
  International Journal of Surgery, 2014
\item
  Oomen KP, Modi VK, Maddalozzo J. Thyroglossal duct cyst and ectopic
  thyroid: surgical management. Otolaryngol Clin North Am. 2015
  Feb;48(1):15-27.
\end{enumerate}

\textbf{LEGENDS}

\textbf{{[}Figure 1{]}} Pre-operative frontal view of midline
submandibular neck mass.

\textbf{{[}Figure 2{]}} Neck CT scan with iv contrast, coronal view,
with the large neck mass, just inferior and adjacent to tongue and
mandible.

\textbf{{[}Figure 3{]}} Intraoperative view of mass in relation to hyoid
bone.

\textbf{{[}Figure 4{]}} Operative specimen with ectopic thyroid and
hyoid bone.\selectlanguage{english}
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