Primary squamous cell carcinoma of thyroid: a case report and review of literature

Abstract

BackgroundThyroid gland lacks squamous epithelium (except in some rare situations like embroyonic remnants or in inflammatory processes); for that reason the primary squamous cell carcinoma (SCC) of thyroid is extremely rare entity, seen only in less than 1% of all thyroid malignancies and is considered almost fatal. So, far, only few case reports have been published in literature.Case presentationHerein we present a 54 years old Saudi female with 3 months history of progressive neck swelling and hoarse voice, who was referred to us by her primary care physician as suspected case of anaplastic carcinoma of thyroid for radical external beam radiation therapy (EBRT). Fine Needle aspiration cytology (FNAC) revealed squamous cell carcinoma. Computed tomography (CT) neck showed 10 × 10 cm mass in left lobe of thyroid invading trachea and skin. Extensive staging work up ruled out the possibility of any primary site of SCC other than thyroid gland. Tumor was found unresectable and was referred to radiation oncology. She received palliative EBRT 30 Gy in 10 fractions. After completion of EBRT, there was progression of disease and patient died 3 months after completion of EBRT by airway compromise.ConclusionPrimary SCC of thyroid is rare and aggressive entity. FNAC is reliable and effective tool for immediate diagnosis. Surgery is a curative option, but it is not always possible as most of cases present as locally advanced with adjacent organs involvement. EBRT alone was found ineffective. Aggressive combined modality (debulking surgery, radiation and chemotherapy) shall be considered for such cases.

Primary squamous cell carcinoma of thyroid gland with local recurrence: ultrasonographic and computed tomographic findings

“…Although several reported cases of PSCCT have been diagnosed by FNA [5,6], the cytological findings are typically nonspecific, and clinical correlation is needed for correct diagnosis [4,7]. In our case, the repetitive cytological results suggested a benign pathology, but postoperative histopathologic examination revealed malignancy.…”

Primary squamous cell carcinoma of the thyroid: a rare type of thyroid cancer

“…It may manifest as neck mass, hoarse voice, weight loss, neck pain, dysphagia, dyspnea, stridor [5]. Clinical presentation depends on invasion of tumor to the adjacent structures such as esophagus, trachea etc.…”

“…So exclusion of metastatic SCC can be provided with endoscopic and radiological imaging. For diagnosis, FNAC is reliable [5]. Kumar et al [9] reported that the presence of dyskeratotic, spindle cells and eosinophilic granular keratin material were essential to diagnose SCC in FNAC.…”

“…There was no consensus of the extent of surgery, chemotherapeutic agents and radiotherapy. In systemic reviews, treatment with surgery, radiotherapy and chemotherapy alone has been found to be effective and it has extremely poor prognosis [3,5]. In the treatment of patients with locally advanced and metastatic disease, combined and aggressive treatments should be considered, but they may not be effective.…”

“…There are two theories regarding the pathophysiology of PSCC. The embryonic rest cell theory depends on squamous cell derivation from remnants of the thyroglossal duct and thymic epithelium [5,6]. According to the second "metaplasia" theory, the source of squamous cells is from follicular, papillary or anaplastic cells [7].…”