Isolated thyroid metastasis from oesophageal primary- a rare clinical scenario

Oesophageal cancer is the second and fifth most common cancer among males and females respectively in India. Most of these cancers present at an advanced age and less than 10% patients survive beyond 5 years after diagnosis [1, 2]. Most of them present initially with dysphagia. Other symptoms include foreign body sensation in the throat, retrosternal pain, weight loss and cachexia. Presence of distant organ metastasis makes it a stage 4 disease according to the latest AJCC staging system. Synchronous occurrence of thyroid metastasis from oesophageal primary is an exceedingly uncommon scenario. Limited number of cases has been described in the English literature. The appropriate management in such group of patients remains unknown at this point of time.


Introduction
Oesophageal cancer is the second and fifth most common cancer among males and females respectively in India. Most of these cancers present at an advanced age and less than 10% patients survive beyond 5 years after diagnosis [1,2]. Most of them present initially with dysphagia. Other symptoms include foreign body sensation in the throat, retrosternal pain, weight loss and cachexia. Presence of distant organ metastasis makes it a stage 4 disease according to the latest AJCC staging system. Synchronous occurrence of thyroid metastasis from oesophageal primary is an exceedingly uncommon scenario. Limited number of cases has been described in the English literature. The appropriate management in such group of patients remains unknown at this point of time.

Case report
A 65 years old lady presented to us with dysphagia to both solids and liquids for the last 10 months. She also complained of foreign body sensation in her throat. Epigastric pain, dyspepsia, nausea, vomiting and anorexia were absent. However she complained of losing few kilos of weight in the last 4 months. She had no other metastatic symptoms. Her past surgical and medical history was unremarkable. Her general survey was normal. On detailed physical examination a swelling was noticed in front of her neck which moved up with deglutition but did not move with protrusion of tongue ( Figure .1).
On palpation the swelling was firm with ill defined margins. Rest of her physical and systemic examination was normal. A barium oesophagogram done showed a narrow irregular segment at the region of mid oesophagus ( Figure.2). An upper gastro intestinal endoscopy showed presence of ulceroproliferative growth in the mid oesophagus. Biopsy was suggestive of moderately differentiated squamous cell carcinoma of the oesophagus. An ultrasonography neck showed presence of hypoechoic mass in the left lobe of thyroid with irregular margins. Fine needle aspiration cytology (FNAC) from the mass showed presence of atypical epithelial cells in cohesive clusters with pleomorphic nuclei and scanty cytoplasm. Overall picture was suggestive of poorly differentiated carcinoma consistent with metastatic cancer. Routine blood tests and thyroid function tests were normal.
A computed tomography scan of the chest showed presence of irregular thickening of the oesophagus without mediastinal involvement .Rest of the metastatic work up was negative. The patient was discussed in multidisciplinary tumour board   where considering the stage of the disease and the good performance status of the patient a decision to start 1st line chemotherapy along with oesophageal stenting was taken. The option of palliative thyroidectomy was explained to the patient in the event of progression of the thyroid lump. However she did not turn up for the scheduled treatment and could not be traced further.

Discussion
The most common primary presenting with thyroid metastases is renal cell carcinoma [3]. Lung, breast, colon, melanoma are other primaries which can present similarly. The most common gastrointestinal primary to metastasize to the thyroid is colorectal. Thyroid metastasis from oesophageal squamous cell cancer is extremely rare and only 4 cases have been reported so far, out of which three have been reported from India. Primary SCC of the thyroid is a rarer entity which affects individuals of age group 50-60 years having history of long standing goitre. They are more common in abnormal thyroid glands. Most of them present with rapid enlargement of a long standing neck mass and are often locally advanced at presentation.
They are usually radio resistant and fatal. Prognosis tends to be poor with median survival less than 6 months. Metastatic thyroid cancer appears to be commoner. It is interesting to note that although the mode of presentation and arriving at final diagnosis was more or less similar in all those cases, there was striking heterogeneity in the way they were treated and their reported outcomes. All the four cases were managed differently. Presence of synchronous thyroid metastases from oesophageal primary is extremely rare. In absence of any treatment guidelines such patients are perhaps best dealt in higher specialty centres with facilities for multimodal therapy.

Conclusion
Presence of asymptomatic thyroid metastasis in a case of primary oesophageal squamous cell carcinoma is an unusual scenario. High index of suspicion should be maintained to make right diagnosis. Due to paucity of such cases no treatment recommendations exist at present. Hence we strongly suggest reporting of such cases. Treatment of such patients should be individualized and requires multidisciplinary tumour board for optimum treatment selection. Most of the patients present with localized pain, often nocturnal, alleviated by simple analgesics [2,3,4]. It often mimics the symptoms of osteoid osteoma [7]. BA has a predilection to tubular bones like tibia, fibula, femur and radius. It particularly affects the metaphyses of these bones, most commonly the distal and proximal ends of tibia [1]. However it may rarely traverse the metaphysic of tubular bones into epiphyses and diaphysis. BA is a diagnostic challenge because in the acute phase the clinical features are minimal and non-specific. The initial infection is localized to a small area and is confined by a thick rim of inflammatory fibrous tissue forming an abscess causing bone destruction.
Due to its diagnostic challenges, various imaging modalities are used to confirm the diagnosis. In the plain radiograph it usually appears as an oval lytic lesion. It may show a finger-like radiolucent tortuous channel extending towards the epiphyseal plate, which, when present, is pathognomonic. If a sequestrum is present, it may mimick an osteoid osteoma.
2) The differential diagnosis for radiological appearance of Brodie abscess include