Hepatic Metastasis in a Nigerian with Differentiate d Thyroid Cancer- An Uncommon Presentation: Case Report

The papillary and follicular histological sub-types of thyroid cancer are referred to as differentiated thyroid cancers. When these tumors metastasize, they rarely do so to the liver. Hepatic metastasis is very uncommon in this group of cancers and has only been reported in a handful of cases. We present one such case in a Nigerian patient and note its unique presentation and with it, we highlight the need for careful attention to be paid to clinical and investigation findings when attempts are being made to arrive at a definitive diagnosis in cases of suspected primary liver cell cancers which are common in this part of the world.


INTRODUCTION
Thyroid carcinomas constitute less than 1% of all human cancers. The annual incidence world wide ranges from 0.5 to 10 cases per 100,000 populations with the median age at being 45-50 years [1]. It is two to four times more frequent in women than men [1]. Papillary and follicular thyroid cancers, together, are referred to as differentiated thyroid cancer (DTC). Differentiated thyroid carcinomas are relatively rare despite common incidence of thyroid nodules [2]. DTC often run an indolent course and have a 10-year survival rate as high as 80 95% [1]. Distant metastases are seen in a minority of patients and the reported rates of occurrence range from 4 to 15% [3 common sites of distant metastasis and bone. [8]. Metastasis to other distant sites is relatively rare and involve the brain, breast, liver, muscle and skin. The presence of distant metastasis is the most significant poor prognostic factor for survival with only 50% metastatic patients surviving after 10 years [9]. Liver metastasis from DTC is quite unusual, with a reported frequency of 0.5% [10]. Metastatic liver involvement from DTC is nearly always multiple or diffuse and usually found along with other distant metastases including the lungs, bones and the brain [11]. DTC liver metastasis has a poor prognosis. Surgical resection of liver lesions has been reported to offer the best chance for prolonged survival [12]. What makes the case presented here an interesting one is the fact that thyroid cancer metastases to liver a this represents a novel documentation of same from our region of Africa.

CASE REPORT
A 56-year old Nigerian lady presented with complaints of a 6 month history of abdominal swelling and weight loss. She had felt malaise with a significant drop in appetite over the same period. Her past history was significant for a partial thyroidectomy which was carried out 7 years earlier on account of what was then thought to be a non-malignant thyroid mass.
Examination findings included non hepatomegaly, with no obvious peripheral stigmata of chronic liver disease. She had a well healed scar of a previous thyroidectomy and there were palpable lymph nodes in the deep cervical lymph node group. The nodes were firm, immobile and none-tender. Investigations carried out revealed deranged thyroid function tests (elevated free T 3, low free T 4

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Thyroid carcinomas constitute less than 1% of all human cancers. The annual incidence worldwide ranges from 0.5 to 10 cases per 100,000 populations with the median age at diagnosis two to four times men [1]. Papillary and follicular thyroid cancers, together, are referred to as differentiated thyroid cancer (DTC). Differentiated thyroid carcinomas are relatively rare despite common incidence of thyroid nodules [2]. DTC often run an indolent course year survival rate as high as 80-95% [1]. Distant metastases are seen in a minority of patients and the reported rates of occurrence range from 4 to 15% [3][4][5][6][7]. The asis are the lung er distant sites is relatively rare and involve the brain, breast, liver, muscle and skin. The presence of distant metastasis is the most significant poor prognostic factor for survival with only 50% metastatic patients surviving after 10 years [9]. Liver metastasis from DTC is quite unusual, with a reported frequency of 0.5% [10]. Metastatic liver involvement from DTC is nearly always multiple or diffuse and usually found along with other distant metastases including the lungs, bones C liver metastasis has a poor prognosis. Surgical resection of liver lesions has been reported to offer the best chance for prolonged survival [12]. What makes the case presented here an interesting one is the fact that thyroid cancer metastases to liver are rare, and this represents a novel documentation of same year old Nigerian lady presented with complaints of a 6 month history of abdominal swelling and weight loss. She had felt malaise with a significant drop in appetite over the same period. Her past history was significant for a ich was carried out 7 years earlier on account of what was then malignant thyroid mass.
luded non-tender with no obvious peripheral stigmata of chronic liver disease. She had a well a previous thyroidectomy and there were palpable lymph nodes in the deep cervical lymph node group. The nodes were firm, tender. Investigations carried out revealed deranged thyroid function tests and Thyroid Stimulating Hormone), markedly ele alkaline phosphatase and gamma glutamyl transpeptidase (ɣGT), with other liver function tests being normal. Screens for hepatitis B and C were negative.
A chest computed tomography (CT) scan showed suspected bilateral pulmonary metastatic lesions (Figure 1) Stimulating Hormone), markedly elevated gamma glutamyl GT), with other liver function tests being normal. Screens for hepatitis B and C computed tomography (CT) scan bilateral pulmonary metastatic abdominal ultrasound (CT) scan revealed a huge intrahepatic mass in segments 4a, 4b and 5 with lobulated margins and heterogeneous ure 2).

Computed tomography image of the thorax showing multiple "cannon ball" ns of suspected lung metastasis
Computed tomography image of the -hepatic mass in segments 4a, 4b and 5 with lobulated margins and heterogeneous enhancement fetoprotein level and colonoscopy guided biopsy of the liver mass which histology were reported as sections containing thyroid and not hepatic tissue. It further revealed variously sized thyroid follicles lined by cuboidal cells (Figure 3). Thyroid Ultrasound scan showed the presence of hypervascular nodules in the thyroid and matted cervical nodes in the upper carotid sheath. A whole body scintigraphy revealed normal tracer bio-distribution in the thyroid gland with abnormal uptake in the lungs and liver indicative of multiple functioning metastases in these latter organs.
A diagnosis of distant (lungs and hepatic) metastasis from a thyroid cancer was made and the patient has since been referred for expert radio-oncologic assessment and management.

DISCUSSION
Liver metastasis from DTCis quite rare, with a reported frequency of 0.5% [10]. As of 2012, a review of literature by Hong-Jun Song et al. [11] reported that only ten cases have been documented in the literature. Three were males and seven females with an average age of about 63 years (range from 32 to 85 years). Histologically, the primary tumor was identified as papillary in four patients, follicular in five, and Hűrthle cell thyroid cancer in one patient. Our patient presented herein, fits well the typical epidemiological descriptors as she is 56 years old. Unfortunately, the histology of the primary tumor of this patient is unknown as pathology was not carried out on the thyroid gland when it was removed 7 years ago. Hence, we cannot comment about the primary histological variant. This is because transformation of histopathologic types may occur in liver metastases from DTC [11]. This phenomenon has been documented in two of the patients in the 2012 review where the primary tumors were follicular and papillary but their liver metastasis were a unique entity described as follicular variant of papillary thyroid carcinoma.
The indolent growth nature of DTC is reflected considering that metastasis occurred after 7 years of the primary thyroid mass been surgically excised. Similar occurrence has been reported in the literature in which a metastatic thyroid liver disease was detected 32 years after thyroidectomy was performed for a follicular thyroid tumor [13]. This underscores the need for a lifelong followup because of the long time risk of recurrence of the disease.
Metastatic liver involvement from DTC is nearly always multiple or diffuse and is usually found along with other distant metastases [11] as was in this index patient who had accompanying lung metastasis at presentation.
The patients seldom present with symptoms referable to the defacto liver involvement except when the masses were huge [11]. This was also mirrored in our report. The survival rate after liver metastases is poor; however, Song et al. [11] opines that this may not be attributable to the liver metastases alone as multiple other vital organs are concurrently involved by this time.

CONCLUSION
The case report highlights the possibility of such rare occurrence of hepatic metastasis from DTC.
To the best of our knowledge, this represents a novel documentation of this association from our environment. Because of the possible confusion with a primary liver cell carcinoma which is relatively common in our region of the world, the usefulness of histological diagnosis of doubtful intra-hepatic lesions is also highlighted.

CONSENT
All authors declare that written informed consent was obtained from the patient (or other approved parties) for publication of this case report and accompanying images.

ETHICAL APPROVAL
It is not applicable.