<div>Sean Fang FRCS (ORL-HNS)</div><div>Lisi Hu MBBS</div><div>Karan Kapoor FRCS (ORL-HNS)</div><div>(All authors are affiliates of below institution)</div><div>Department of Otolaryngology</div><div>East Surrey Hospital</div><div>Redhill</div><div>Surrey</div><div>UK</div><div>Corresponding author:</div><div>Sean Fang FRCS (ORL-HNS)</div><div>Department of Otolaryngology</div><div>East Surrey Hospital</div><div>Redhill</div><div>Surrey</div><div>UK</div><div>RH1 5RH</div><div>Sean.fang@nhs.net</div><div>+447708806569</div><div>We have no conflicts of interest or financial sources to declare.</div><div>Key Clinical Message</div><div>This case highlights the diagnostic challenge of PTL in patients with a
rapidly expanding anterior neck mass. In addition to tracheal invasion,
progressive airway compression can lead to pulmonary oedema and
cardiomyopathy.</div><div>Abstract</div><div>Rapidly expanding thyroid lesions with tracheal invasion are typical
characteristics of anaplastic and high-grade thyroid carcinomas.
However, primary thyroid lymphoma (PTL) must also be considered as a
differential. We present a rare case of PTL with direct invasion and
compression of the trachea resulting in pulmonary oedema and
cardiomyopathy.</div><div>Introduction</div><div>Rapidly expanding thyroid lesions with tracheal invasion are typical
characteristics of anaplastic and high-grade thyroid carcinomas.
However, primary thyroid lymphoma (PTL) must also be considered as a
differential. Aggressive thyroid lesions can compromise the airway
through compression and/or direct invasion of the tracheal wall.</div><div>We present a rare case of PTL which presented with compression and
invasion of the anterior tracheal wall causing acute respiratory
distress secondary to negative pressure pulmonary oedema with
cardiomyopathy.</div><div>Case report</div><div>A 57-year-old woman with known hypothyroidism presented to her GP with a
few months’ history of orthopnoea and intermittent hoarseness. An
ultrasound showed right sided thyroid enlargement with an isthmus nodule
extending to the left lobe. She developed progressive tightness in the
neck and was seen in the rapid access ENT clinic. Flexible nasendoscopy
examination was normal and the patient underwent an urgent
ultrasound-guided Fine Needle Aspiration Cytology (FNAC), which
suggested possible lymphocytic thyroiditis. Subsequent core-biopsy
showed scanty lymphocytes and was non-diagnostic.</div><div>Nineteen days following ENT review, she presented to our Emergency
Department with worsening shortness of breath. The patient was diagnosed
with type 2 respiratory failure with acidosis and raised troponin. A
computed tomography pulmonary angiogram (CTPA) on admission demonstrated
severe ground glass shadowing. She was therefore admitted under the
medical team with working diagnoses of atypical pneumonia. An
echocardiogram demonstrated a reduced ejection fraction of 32% with
left ventricle apical hypokinesia and lateral wall akinesia. Cardiac MRI
demonstrated an apical left ventricle hypertrophy suggestive of
cardiomyopathy. As a result, a diagnosis of Takutsubo-like stress
cardiomyopathy was made.</div><div>Nineteen days from admission, the patient suffered a cardiac arrest.
Whilst spontaneous ventilation was achieved through cardiopulmonary
resuscitation, worsening type 2 respiratory failure required intubation
and mechanical ventilation in the Intensive Care Unit (ICU). The cause
of arrest was attributed to acute respiratory distress syndrome
secondary to acute pulmonary oedema.</div><div>In light of her cardiorespiratory deterioration, the admission CTPA was
re-reviewed where a large goitre with heterogenous enlargement was noted
with significant tracheal compression resulting in a minimal lumen size
of 6mm (figures 1 &amp; 2). No direct invasion of the trachea was seen on
imaging. The CT and clinical impression was of a rapidly progressive and
aggressive thyroid malignancy such as anaplastic carcinoma, rather than
thyroiditis as suggested on ultrasound. In view of the airway
obstruction, the aetiology of the ground glass appearance of the lungs
was revised to pulmonary oedema secondary to negative pressure
respiration rather than an infective cause.</div><div>On day two of intubation, ENT were approached regarding surgical
management of the airway as the patient was deemed unsuitable for
extubation due to the degree of tracheal compression. Therefore, a
hemithyoidectomy of the larger right lobe of thyroid was planned to
decompress the trachea, gain histological diagnosis and allow extubation
of the patient. Intraoperatively the thyroid lesion was more consistent
with an infiltrative pathology involving the strap muscles. The thyroid
was grossly enlarged, homogeneously firm with an appearance more
suggestive of lymphoma rather than carcinoma. The trachea was identified
distally, and the thyroid cartilage was exposed to gain control of the
field. The infiltration extended laterally toward the carotid sheath,
hence an attempt at a formal hemithyroidectomy was not feasible. On
dissecting the thyroid tissue from the trachea, it was evident on the
right lateral aspect there was clear invasion into the lumen of the
trachea. This was inspected using a 0-degree and 30-degree Hopkins Rod.
We decided a wedge resection of the thyroid down to the trachea and the
formation of a tracheostomy would be the safest option. A size 8-0
cuffed Shiley tracheostomy tube was inserted.</div><div>The patient stepped down to ward-based care after 17 days on ICU.
Histological diagnosis confirmed diffuse large B-cell lymphoma. Since
her discharge, she has completed six cycles of R-CHOP chemotherapy (four
cycles at full dose) and will have two further cycles of Rituximab
complete her chemotherapy treatment. She has been followed up closely by
Cardiology, where her ejection fraction had improved from 32% to 62%
and will undergo a repeat cardiac MRI and echocardiogram and
decannulation of her tracheostomy upon completion of chemotherapy.</div><div>Discussion</div><div>Thyroid lymphoma can be classified into primary and secondary
(non-thyroidal lymphoma metastasises to the thyroid gland). PTL is rare,
accounting for less than 5% of all thyroid malignancies. The thyroid
gland does not typically contain lymphoid tissue, therefore PTL tends to
occur in pathological glands. Autoimmune thyroiditis (Hashimoto’s
thyroiditis) is the most common risk factor and is associated with 80%
of cases of PTL and confers 40-80 times the risk of developing PTL
compared to those without thyroiditis.</div><div>Whilst traditional FNAC plays an important role in diagnosing thyroid
nodules, it is of limited value in PTL due to the challenge in
distinguishing between lymphoma, lymphocytic thyroiditis and anaplastic
thyroid carcinoma. However, advances in flow cytometry and
immunohistochemistry have increased the sensitivity of FNAC in
diagnosing PTL. Core needle and incisional biopsy techniques provide
significant higher sensitivity and classifies 95% of lymphomas in
typical cases. Computed tomography can suggest a diagnosis where
anaplastic thyroid carcinoma displays more heterogenous attenuation
within the lesion often with evidence of calcification and necrosis,
whereas PTL and involved lymph nodes have a more homogenous appearance.</div><div>Conclusion</div><div>This case highlights the diagnostic challenge of differentiating between
PTL and anaplastic thyroid carcinoma in patients with a rapidly
expanding anterior neck mass. Tracheal invasion is a feature seen more
commonly in anaplastic thyroid cancer due to release of proteinases from
neoplastic giant cells, which resemble osteoclasts associated with
tracheal cartilage. Necrosis is uncommon in PTL and whilst extension
beyond the thyroid capsule is relatively common, erosion of adjacent
structures is unusual.</div><div>Invasion of the trachea from PTL is very rare, especially prior to
treatment, with fewer than 5 cases reported in the literature.
Furthermore, this case demonstrates the potential cardiopulmonary
sequelae of progressive airway compression which resulted in negative
pressure pulmonary oedema and cardiomyopathy.</div><div>Author Contribution</div><div>Sean Fang: Literature review and discussion review.</div><div>Lisi Hu: write up of case report.</div><div>Karan Kapoor: Supervising Consultant.</div><div>Conflict of Interest and Ethics Approval</div><div>We have no conflicts of interest or financial sources to declare.</div><div>Ethics approval was not required for this article.</div><div>References</div><div>Figure captions</div><div>Figure 1: CT scan showing large thyroid lesion with significant tracheal
compression</div><div>Figure 2: post-tracheostomy CT scan showing the thyroid lesion causing
tracheal deviation and possible invasion.</div>