|Year : 2020 | Volume
| Issue : 6 | Page : 284-287
Primary Squamous Cell Carcinoma of Thyroid Gland: A Report of Two Cases
Abhay Vilas Deshmukh, Vitaladevuni B Shivkumar, Kailas S Kotalwar, Nitin M Gangane
Department of Pathology, Mahatma Gandhi Institute of Medical Sciences, Sevagram, Wardha, Maharashtra, India
|Date of Submission||23-Mar-2020|
|Date of Decision||11-May-2020|
|Date of Acceptance||02-Jun-2020|
|Date of Web Publication||25-Jul-2020|
Dr. Vitaladevuni B Shivkumar
Department of Pathology, Mahatma Gandhi Institute of Medical Sciences, Sevagram, Wardha - 442 102, Maharashtra
Source of Support: None, Conflict of Interest: None
Primary squamous cell carcinoma of the thyroid gland (PSCCT) is a rare malignancy seen in <1% of all primary malignancies of the thyroid gland, and it carries a poor prognosis. The patient usually presents with metastasis at the time of the presentation. Here, we report two cases of PSCCT. On clinical assessment, both the cases were considered as suspicious for malignancy. Radiological investigations showed a nodular lesion measuring 5 cm × 3.5 cm × 2 cm with internal vascularity in the first case while large multilobulated mass measuring 8.4 cm × 8.3 cm × 5.6 cm compressing the surrounding structures in the second case. Both of the patients underwent surgical interventions. The final diagnosis of PSCCT was made after thorough investigations excluding the possibility of primary focus elsewhere in the body. Both patients succumbed to death within 8 months. We report these two cases of PSCCT due to the rarity of this entity in literature.
Keywords: Primary squamous cell carcinoma, thyroid gland, thyroid malignancy
|How to cite this article:|
Deshmukh AV, Shivkumar VB, Kotalwar KS, Gangane NM. Primary Squamous Cell Carcinoma of Thyroid Gland: A Report of Two Cases. J Med Sci 2020;40:284-7
| Introduction|| |
Primary squamous cell carcinoma of the thyroid gland (PSCCT) accounts for <1% of all thyroid malignancies and has a very poor prognosis. It usually presents as an incidental finding with extensive infiltration in surrounding structures. The possibilities of other primary focuses of squamous cell carcinoma (SCC) must always be excluded before labeling as a PSCCT. The overall survival rate in these patients is usually poor. Here, we report two cases in our institute, which were considered suspicious for malignancy. Histopathological examination after surgery revealed a diagnosis of PSCCT.
| Case Report|| |
A 68-year-old woman presented at the surgery outpatient department (OPD) at Mahatma Gandhi Institute of Medical Sciences, Sevagram, a tertiary care hospital in rural Central India with the complaints of swelling over the anterior aspect of the neck for 2 months [Figure 1]a. It was insidious in onset and gradually progressive in nature and was associated with dysphagia (nonspecific for fluids or solids) and hoarseness of voice. She also complained of a gradual reduction in appetite and oral intake with worsening dysphagia, which leads to a significant weight loss. There was no history of thyroid cancer in her family, as well as no history of neck irradiation in the past. She was cachexic in appearance, and local examination revealed the presence of thyroid swelling on the left side, measuring 5 cm × 4 cm in size. It was nontender, hard in consistency and was moving with deglutition. There was also the presence of cervical lymphadenopathy on the right side measuring 2 cm × 2 cm in size, firm in consistency. The thyroid hormone profile showed high thyroid-stimulating hormone (TSH) (29.86 mIU/L) while rest values were within the normal range, total T3: 86.92 ng/dL, and total T4: 5.32 μgm/dL. (Normal range; Total T3: 80–220 ng/dL, Total T4: 5–12 μgm/dL and TSH: 0.4–4 mIU/L). Ultrasonography (USG) neck showed a well-defined heterogeneously echotexture solid nodular lesion measuring 5 cm × 3.5 cm × 2 cm with multiple calcific foci within it. The lesion was not involving any external structures. On color Doppler imaging, the lesion shows internal vascularity [Figure 2]a and [Figure 2]b. There were also multiple lymph nodes noted in the right mid jugular region (Level III) showing peripheral vascularity and punctate calcification with loss of hilum. It was reported as a malignant lesion in the thyroid gland. Fine-needle aspiration cytology (FNAC) done at outside laboratory revealed poorly differentiated carcinoma, and histopathological confirmation was advised.
|Figure 1: (a) Presence of thyroid swelling on the right side and cervical lymphadenopathy on left side in a 68-year-old female patient; (b) Presence of right thyroid swelling in a 59-year-old female patient|
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|Figure 2: Ultrasonography neck in case of a 68-year-old female; (a) Transverse ultrasonography image showing a well-defined heterogeneously echotextured solid nodular lesion (arrow) with multiple calcific foci within it; (b) On color Doppler imaging, the lesion shows internal vascularity (arrow)|
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A 59-year-old woman presented at surgery OPD with complaints of swelling over the anterior aspect of the neck for 10 years; now increased in size since 3 months, it was progressive in nature [Figure 1]b. There was no history of previous neck irradiation or any symptoms suspicious of malignancy or any relevant family history. Physical examination revealed stable vital signs. Local examination revealed nodular swelling in front of the neck, more on the right side, measuring 8 cm × 5 cm. It was firm in consistency, nontender and was moving with deglutition. Computed tomography (CT) neck revealed the presence of large multilobulated heterogeneously enhancing mass lesion in the right anterolateral aspect of neck involving right lobe of thyroid measuring 8.4 cm × 8.3 cm × 5.6 cm extending from C4 to T2 vertebral level. It was displacing and compressing right carotid vessels. The mass caused the leftward deviation of the trachea and esophagus [Figure 3]a and [Figure 3]b. Histopathological confirmation was advised to rule out neoplastic etiology. The thyroid hormone profile showed elevated TSH (75.89 mIU/L) while reduced T3 and T4 values; total T3: 62.79 ng/dL and total T4: 3.61 μgm/dL. On FNAC, it was reported as a colloid goiter with cystic change.
|Figure 3: Computed tomography neck in case of a 59-year-old female; (a) Axial noncontrast enhanced computed tomography neck showing a well-defined multinodular predominantly cystic mass with peripheral wall calcification (arrow) and eccentric solid component; (b) Axial contrast computed tomography neck showing peripheral enhancement with heterogeneously enhancing solid component (arrow) in the right lobe of thyroid displacing and compressing right carotid vessels. The mass is also causing leftward deviation of trachea and esophagus|
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Preoperative resectability was evaluated with the help of radiological findings of USG and CT scan. Whole-body 18-Fluorodeoxyglucose positron emission tomography/CT was done in both cases, which was suggestive of the metabolically active lesion in thyroid in both cases. No other lesion was noted otherwise else in the whole body. A total thyroidectomy was planned in both cases. Intraoperatively, the surgeons found that the tumor was tightly adherent to the trachea and trachea-esophageal groove, and there was difficulty in separation of the tumor. The removal of further tumor could cause damage to the recurrent laryngeal nerve, so intraoperative decision was taken to preserve these structures, thus limiting the resection. Thus, debulking surgery was done in both cases. On histopathology, grossly, the tumor measured 4.5 cm × 2.5 cm × 1.5 cm and 8 cm × 6 cm × 4.2 cm in cases 1 and 2, respectively. Cut surface showed the presence of tumor mass along with necrotic areas at places. Microscopically, H and E stained sections showed tumor composed of malignant squamous cells along with normal thyroid glands [Figure 4]. The tumor cells were arranged in nests, sheets, and island patterns. These cells exhibited large pleomorphic nuclei with abundant eosinophilic cytoplasm [Figure 5]. There was also the presence of keratinization at places. Few areas also showed the infiltration of malignant cells into thyroid parenchyma. All the surrounding thyroid follicles were normal in appearance [Figure 4]. Immunohistochemistry (IHC) showed positivity for Pan-Cytokeratin (CK) in tumor cells [Figure 6], while thyroglobulin and thyroid transcription factor-1 (TTF-1) were negative in our case. A final diagnosis of PSCCT was made based on typical histopathological features, IHC findings and in the absence of any other primary focus in adjacent structures in the body.
|Figure 4: Section showing malignant squamous epithelial cells (yellow arrow) within the thyroid gland along with the presence of benign thyroid follicles (green arrow) (H and E, ×100)|
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|Figure 5: Section showing islands of malignant squamous cells within the stroma containing lymphocytes (H and E, ×400)|
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|Figure 6: Section showing positivity for Pan-Cytokeratin in islands of malignant squamous cells (green arrow) along with the presence of normal thyroid follicles (yellow arrow) (immunohistochemistry, ×100)|
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Postoperatively, both cases were advised for chemoradiation therapy. The first case did not agree for the same due to personal religious belief, but she was in regular follow-up. The second case received radiation of 60 Gy in 30 fractions for 6 weeks, along with five cycles of weekly concomitant chemotherapy (Inj. Cisplatin 65 mg). Both the cases succumbed to death within 8 months due to airway obstruction.
| Discussion|| |
PSCCT is an unusual entity which represents <1% of all thyroid malignancies,, as the thyroid gland lacks squamous epithelium. Few cases have been reported in the literature about this entity.,, Females are more commonly affected than males and present usually in fifth to sixth decades of life like that of our cases. The patient usually presents with complaints of the enlarged thyroid gland (60%), followed by symptoms related to infiltration and compression of surrounding structures due to the enlarged thyroid gland. It includes dyspnoea/dysphagia (20%), changes in voice (15%), and in some cases, enlarged cervical lymph nodes., It usually behaves as an anaplastic carcinoma with median survival being <6 months, oftentimes due to adjacent metastasis causing airway compression and infiltration. One of our case presented with rapid growth in an already existing benign thyroid swelling. On FNAC, one of the cases was suggestive of poorly differentiated carcinoma, while FNAC did not help us to achieve a proper preoperative diagnosis in second case. The reason could be the inability of the needle to reach a proper site of tumor as unguided FNAC is a blind procedure.
The differential diagnoses include papillary carcinoma with foci of squamous differentiation, which usually occurs in 15%–45% of papillary carcinomas, anaplastic thyroid carcinoma with squamous differentiation, carcinoma showing thymus like element and metastasis from adjacent organs., The papillary carcinoma thyroid with squamous differentiation shows the typical presence of nuclear features in tumor cells like orphan Annie eye nuclei, intranuclear cytoplasmic inclusions, which were absent in our case. The anaplastic carcinoma thyroid with squamous differentiation shows positivity for TTF-1, thyroglobulin, CK5/6, and p53 in tumor areas. The origin of PSCCT is questionable as the thyroid gland lacks squamous epithelium. Various theories have been considered regarding its origin. First, the “embryonic nest” theory suggested that squamous cells might have derived from remnants of thyroglossal duct or thymic epithelium of third branchial cleft. Second, the “metaplasia” theory, which suggested that these cells can develop from chronic environmental stimuli (inflammation and Hashimoto's thyroiditis)., Third, the “dedifferentiation” theory which suggested that existing malignant conditions like anaplastic, follicular, papillary and medullary carcinomas can dedifferentiate into SCC. Few studies have shown that positivity for CK-19 in PSCCT and negativity for the markers like thyroglobulin, TTF-1, calcitonin and carcinoembryonic antigen., In our case, IHC showed positivity for Pan-CK in tumor cells while thyroglobulin (TTF-1) and calcitonin were negative in our case.
The treatment usually includes surgical excision of the tumor with adjuvant chemoradiation., As such, no standard treatment guidelines have been developed due to the rarity of this tumor. Few studies have suggested that this tumor is radio-resistant and even poorly responsive to chemotherapy., Thus, the best option include early diagnosis and complete surgical excision. However, it is quite impossible in advanced cases with wide infiltration in surrounding structures and metastasis.
FNAC was not helpful in the second case in preoperative diagnosis. Cho et al. in this systematic review on PSCCT found that predictability of diagnosis with FNAC was correct in less than one-third of the patients, while >50% of cases were wrongly diagnosed as papillary thyroid carcinoma. This group also included nondiagnostic, which was similar to both of our cases.
| Conclusion|| |
PSCCT is an uncommon and aggressive entity which usually has a poor prognosis. The median survival period is less than a year. Unguided FNAC may not play an important role in the preoperative assessment of the tumor. The complete excision of the tumor is the only convincing prognostic factor; the role of chemoradiation still remains controversial. The patients usually succumb to death due to widespread local metastasis and extensive local invasion.
We would like to acknowledge Dr. Ashok Singh (Assistant Professor, Department of Radiotherapy) and Dr. Mithun Bhoyar (Assistant Professor, Department of Radiodiagnosis), MGIMS, Sevagram, Wardha, Maharashtra, India for details of radiotherapy and radiological investigations of both patients.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patients have given their consent for their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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