Unusual clinical accompaniment of inflammatory thyroiditis preceding hypothyroidism in radiotherapy of head-and-neck cancer

Vijaya Aditya Yadaraju; Aditya Narayan; Shilpa Kandipalli; Praveen Adusumalli; Sweta Sinha; Prabhakar Rao Vatturi Venkata Satya

doi:10.4103/jrcr.jrcr_41_20

CASE REPORT

Year : 2021 | Volume : 12 | Issue : 2 | Page : 82-84

Unusual clinical accompaniment of inflammatory thyroiditis preceding hypothyroidism in radiotherapy of head-and-neck cancer

Vijaya Aditya Yadaraju¹, Aditya Narayan¹, Shilpa Kandipalli², Praveen Adusumalli², Sweta Sinha³, Prabhakar Rao Vatturi Venkata Satya⁴
¹ Department of Radiotherapy, HCG Cancer Centre, Visakhapatnam, Andhra Pradesh, India
² Department of Medical Radiotherapy, HCG Cancer Centre, Visakhapatnam, Andhra Pradesh, India
³ Department of Pathology, HCG Cancer Centre, Visakhapatnam, Andhra Pradesh, India
⁴ Department of Nuclear Medicine, HCG Cancer Centre, Visakhapatnam, Andhra Pradesh, India

Date of Submission	08-May-2020
Date of Acceptance	17-May-2020
Date of Web Publication	26-Apr-2021

Correspondence Address:
Dr. Prabhakar Rao Vatturi Venkata Satya
Department of Nuclear Medicine, HCG Cancer Centre, Visakhapatnam, Andhra Pradesh
India

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/jrcr.jrcr_41_20

Abstract

The authors report an unusual clinical phenomenon of head-and-neck radiotherapy-induced thyroiditis presenting with clinical features of hyperthyroidism on immediate clinical follow-up with raised thyroid hormone levels. Conventional technetium thyroid scan showed a discordantly absent thyroid gland uptake instead of expected thyroid avidity in hyperthyroidism. The thyroid gland subsequently reverting to normal uptake in the postrecovery stage confirmed the thyroiditis nature, with prior radiation to the neck being the possible inciting factor.

Keywords: External beam radiotherapy, image-guided radiation therapy, technetium thyroid scan, thyroiditis

How to cite this article:
Yadaraju VA, Narayan A, Kandipalli S, Adusumalli P, Sinha S, Venkata Satya PR. Unusual clinical accompaniment of inflammatory thyroiditis preceding hypothyroidism in radiotherapy of head-and-neck cancer. J Radiat Cancer Res 2021;12:82-4

How to cite this URL:
Yadaraju VA, Narayan A, Kandipalli S, Adusumalli P, Sinha S, Venkata Satya PR. Unusual clinical accompaniment of inflammatory thyroiditis preceding hypothyroidism in radiotherapy of head-and-neck cancer. J Radiat Cancer Res [serial online] 2021 [cited 2022 May 16];12:82-4. Available from: https://www.journalrcr.org/text.asp?2021/12/2/82/314706

Introduction

External beam radiotherapy is often the definitive treatment for most head-and-neck cancers. Critical conformal organ-sparing radiation therapy with daily image guidance (image-guided radiotherapy [IGRT]) helps restrict radiation dose to normal structures of neck such as parotids and thyroid gland, neck vasculature, and brachial plexus. However, radiation-induced thyroiditis though unusual can manifest in the immediate postradiotherapy phase with features of hyperthyroidism. Recognition of such an entity is essential to avoid unnecessary anti-thyroid drug therapy to control the transient and self-correcting hyperthyroid state. Conventional ^99mtechnetium thyroid scan confirmation of this entity by its initial negative uptake followed by recovered thyroid function and normal uptake highlights this unusual transient clinical manifestation.

case report

A 42-year-old male smoker presented with difficulty in swallowing solids and pain, which forced him to be on a semi-solid diet. He subsequently developed hoarseness of voice without difficulty in phonation or articulation. There was no associated cough or difficulty in breathing. Physical examination revealed a palpable lesion on the base of the tongue with induration and a hard, fixed, 2 cm × 1 cm-size, right Level II cervical lymph node. Contrast-enhanced computed tomography of the neck revealed a right lateral pharyngeal wall mass extending into the right vallecula with right Level II cervical nodes [Figure 1]. A video laryngoscopic examination showed an ulcerative growth in the right vallecula extending into the right lateral pharyngeal wall. Biopsy from the mass revealed a well-differentiated squamous cell carcinoma.

Figure 1: Contrast-enhanced computed tomography neck axial, sagittal, and coronal sections showing right lateral pharyngeal wall mass extending into the right vallecula

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In view of the T2/N1 stage of the disease, a multidisciplinary tumor board opted for upfront radical radiotherapy with concurrent platinum chemotherapy.^[1] Radiotherapy planning computed tomography (CT) scan with thermoplastic immobilization of the head-and-neck cast was followed by image segmentation and radiation treatment planning with target dose conformation and organ sparing [Figure 2]. Radical radiation therapy was administered at a total dose of 66 Gray in 33 fractions along with weekly concurrent cisplatin using IGRT.

Figure 2: Three-dimensional dose color wash mapping of isodoses of radiation treatment planning and c

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The patient had an uneventful 6½-week course of chemoradiation and on clinical follow-up after a month, there was total regression of the oropharyngeal mass and cervical adenopathy. However, the patient had developed severe asthenia and progressive weight loss of more than 5 kg in a month following the completion of radiotherapy.

There was no fever, loss of appetite, cough, or any other symptoms to account for the significant weight loss. Routine hematological and biochemical investigations were inconclusive. ¹⁸Fluorine-fluorodeoxyglucose-positron emission tomography/CT (PET/CT) was performed for postradiation disease status evaluation, and thyroid hormone profile was done to account for the clinical features. PET/CT showed complete regression of the oropharyngeal lesion with no residual morphological disease or any abnormal metabolic activity, and there was no evidence of metastasis [Figure 3].

Figure 3: Whole-body ¹⁸fluorine-fluorodeoxyglucose-positron emission tomography-computerized tomography showing complete metabolic and morphologic regression of nasopharyngeal mass and no residual disease or metastasis

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Surprisingly, there was an elevation of serum T3 and T4 levels and suppression of thyroid-stimulating hormone (TSH): T3: 2.30 ng/mL, T4: 14.5 μg/dL, and TSH: <0.015 μIU/mL. These findings posed a clinical dilemma of diametrically opposite thyroid hormonal profile of raised levels instead of the usual postradiotherapy diminution.

A radiation therapy-induced thyroiditis was thus suspected due to clinical and hormonal hyperthyroid state in an immediate post radiotherapy setting. A ^99mtechnetium thyroid scan was performed, which confirmed the classical thyroiditis features of absent thyroid uptake and normal salivary gland uptake [Figure 4], thus confirming the diagnosis of thyroiditis. As the clinical hyperthyroid state was not alarming, the patient was put on beta-blocker therapy instead of anti-thyroid drug therapy to tide over the hyperthyroid symptoms and sympathetic effects.

Figure 4: ^99mTechnetium thyroid scan showing absent thyroid uptake with normal salivary gland uptake

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Clinical and hormonal review was done 3 months later. The patient became completely symptom free and gained weight. The thyroid profile showed hypothyroid range, and repeat ^99mtechnetium thyroid scan revealed complete recovery of thyroid uptake with diffuse avidity [Figure 5] despite apparent hypothyroid hormone profile, thus confirming the earlier suspected thyroiditis status. The patient was then put on thyroid hormone replacement with 0.1-mg thyroxine. A follow-up done after 2 months found him clinically euthyroid and in a cancer-free state.

Figure 5: Follow-up ^99mtechnetium thyroid scan revealing complete recovery of thyroid uptake with diffuse avidity

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Discussion

Classical subacute thyroiditis, also known as De Quervain's thyroiditis, is not a usual clinical occurrence which evades correct and timely diagnosis due to the protean presentation of painful thyroid, tender neck swelling and a hyperthyroxinemia, mild hyperthyroid features, and mildly raised thyroid hormones with clinching evidence by absent thyroid uptake on radioactive iodine or technetium thyroid scan which reverts to normal uptake after clinical recovery in 2–3 months.^[2],[3]

The usual incriminating factor is preceding upper respiratory tract viral episode or postexanthematous infections.^[4] Interestingly, radiotherapy-induced painless thyroiditis is not clinically encountered in routine practice. IGRT with modulated conformation restricts radiation dose to the normal structures of the neck such as parotid glands, larynx, and pharyngeal constrictor muscles while delivering therapeutic doses to the tumor target volumes.^[5],[6] However, in situations where tumor volumes and normal structures overlap significantly, like thyroid gland in advanced carcinoma hypopharynx and parotid gland in Level II lymph node metastasis, these normal structures are allowed to get higher radiation dose for better dosimetric coverage of the tumor volume for improved survival outcomes at the cost of quality of life.^[7]

Thus, despite critical organ-sparing radiation techniques, thyroid gland irradiation is unavoidable. This needs long-term follow-up of head-and-neck malignancies postradiotherapy with regular thyroid profile evaluation to anticipate hypothyroidism, which usually necessitates thyroid hormone replacement therapy.^[8],[9] Transient radiation-induced hyperthyroid state is usually missed or evades clinical recognition.

The transient hyperthyroid phase of radiation-induced thyroiditis has been surreptitiously detected during the initial hyperthyroxinemic phase with weight loss, heat intolerance, and mild tremors. The thyroid hormone profile showed hyperthyroid range, and ^99mtechnetium thyroid scan confirmed thyroiditis diagnosis with absent thyroid uptake and subsequent reversal to an avid uptake after clinical recovery. This case thus unearthed the post head-and-neck radiation therapy-induced thyroiditis with spontaneous and complete clinical, hormonal, and functional recovery of the thyroid gland.

Conclusion

Transient hyperthyroxinemia encountered in postradiotherapy thyroiditis in head-and-neck irradiation highlights the existence of this clinical possibility in the immediate postradiation therapy follow-up of oropharyngeal carcinoma. The diagnosis is confirmed by the conventional ^99mtechnetium thyroid scan in the immediate clinical and hormonal hyperthyroid state showing absent thyroid gland uptake, subsequently reverting to normal or avid thyroid gland uptake and clinical recovery of the transient hyperthyroid state to euthyroid or hypothyroid state in the long term. This case thus opened a vista for clinicians to consider this uncommon phenomenon in the short- and long-term follow-up patients of head-and-neck irradiation.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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