|Year : 2015 | Volume
| Issue : 2 | Page : 170-173
Unusual cause of solitary pulmonary nodule
Yasser M Aljehani, Zeead M Al-Ghamdi, Yasser F El-Ghoniemy
Department of Surgery, Cardiothoracic Unit, King Fahd Hospital of the University, University of Dammam, Dammam, Kingdom of Saudi Arabia
|Date of Web Publication||6-May-2015|
Yasser M Aljehani
Department of Surgery, Cardiothoracic Unit, King Fahd Hospital of the University, University of Dammam, Dammam
Kingdom of Saudi Arabia
Source of Support: None, Conflict of Interest: None
Papillary thyroid carcinoma is a common type of differentiated thyroid neoplasms with metastasis mostly described in the literature as occurring in the thyroid gland or in the surrounding cervical lymph nodes. We report a case of a 40-year-old lady who underwent thyroidectomy for papillary thyroid carcinoma 26 years prior to her presentation for solitary pulmonary nodule. Wedge resection of the nodule is consistent with metastatic papillary thyroid carcinoma. Although it is rare to have a remote history and a solitary lesion, it is vital to keep the possibility of metastasis in mind when such a presentation occurs.
ملخص البحث :
يعتبر سرطان الغدة الدرقية الحليمية من أكثر أنواع سرطان الغدة الدرقية شيوعا. وينتشر هذا النوع من السرطان في الغدد اللمفاوية بمنطقة الرقبة، ونادرًا ما يكون انفراديا في أماكن أخرى. يعرض الباحثون حالة مريضة في الأربعين من العمر تم تشخيص سرطان الغدة الدرقية الحليمية لديها قبل 62 عامًا وقد خضعت لاستئصال الغدة الدرقية وخلال المتابعة الطويلة تبين وجود عقدة رئوية وبعد استئصالها أتضح انها انتشار لسرطان الغدة الدرقية الحليمية.
Keywords: Metastasis, papillary thyroid carcinoma, solitary pulmonary nodules
|How to cite this article:|
Aljehani YM, Al-Ghamdi ZM, El-Ghoniemy YF. Unusual cause of solitary pulmonary nodule. Saudi J Med Med Sci 2015;3:170-3
| Introduction|| |
The national cancer registry in the Kingdom of Saudi Arabia (KSA) reports that 10.3% of the Saudi female population between the ages of 30 and 44 years suffer from thyroid cancer. This makes it the second most common cancer after breast carcinoma. Taking all age groups together, thyroid cancer accounts for 9.4% of cancers in Saudi females.
The Eastern Province, a region in the Kingdom with the fourth highest population, reports an age-standardized incidence of thyroid cancer as 4/100,000 population. This makes thyroid cancer rank the third in women in the Eastern Province. Metastasis is usually to regional lymph nodes and rarely distant. , We present a case of papillary thyroid carcinoma with its rare metastasis in the lung as a solitary pulmonary nodule.
| Case report|| |
This is a report of a Saudi female who first came to medical attention at the age of 20 years when she complained of gradually increasing midline neck swelling of 8 months' duration associated with dysphagia, dyspnea and hoarseness of voice. There were no thyrotoxic symptoms. On examination, she had a midline neck swelling involving the left thyroid lobe. The trachea was shifted to the right. She underwent an uneventful left lobectomy and isthmectomy and had an uneventful postoperative course. Histopathology report was consistent with papillary carcinoma of the thyroid.
Two years later, a small left pretracheal nodule was found. She underwent excisional biopsy, which was consistent with metastatic papillary thyroid carcinoma. Since then, she has been on regular follow-up with the oncology team and had had no evidence of recurrence. Twenty-six years later, she presented with a history of occasional shortness of breath on exertion for one month. This was exacerbated by walking and relieved with rest, and associated with left-sided chest pain. Chest X-ray revealed a solitary left lower lobe nodule [Figure 1], which was confirmed and better characterized by chest computed tomography [Figure 2]a and b. She underwent wedge resection of the left lower lobe nodule. Gross examination revealed a grayish-white mass measuring 2.3 cm × 1.8 cm × 2.1 cm in size. Histopathology report revealed a papillary carcinoma consistent with metastatic papillary thyroid carcinoma [Figure 3]a and b. She had uneventful postoperative course and was referred to the oncologist. Follow-up imaging done 1-year later showed no evidence of recurrence.
| Discussion|| |
The most common type of thyroid carcinoma is well-differentiated thyroid carcinoma, 79% of which are categorized as papillary, arising from follicular cells. Other neoplasms arising from follicular cells include Hurthle cell, follicular and anaplastic carcinoma. Medullary thyroid cancer is derived from the parafollicular cells (C-cells). , Papillary thyroid cancer usually affects women with a mean age of 27.65 years with a male-to-female ratio is 1:17. This type of malignancy tends to spread via the lymphatics, forming microscopic multifocal and multi-centric lesions in the gland as seen in 44.8% of cases. The regional lymph node involvement is seen in 27.4% of cases.  Extra-thyroidal spread has also been reported most commonly to the surrounding muscle (8%), followed by recurrent laryngeal nerve (6%) and trachea (5%).  Systemic metastasis has been found in 7.9% of cases at the time of diagnosis.  With prolonged follow-up of up to 20 years, it can reach 40%. , Review of the existing English literature revealed a total 16 such latent cases of metastases that were reported up to 47 years after the original diagnosis of thyroid carcinoma. , There is decreasing the frequency in mediastinal lymph nodes, lungs and bones that correlate with advanced progression of the disease.
The characteristic histological features of this cancer include psammoma bodies, intranuclear grooves, and cytoplasmic inclusions.  Immunostaining patterns of cytokeratins (CKs) has recently helped in the diagnosis of different surgical pathology wherein thyroid and lung cancers it is positive for CK7 and negative for CK20.  Prognosis in most patients with this cancer is excellent with a 10-year survival of >95% without metastasis.  There are, histologically, some aggressive variants associated with poorer prognosis. These include the tall cell variant, columner, oxyphilic and diffuse sclerosis variant.  The significance of micrometastasis parallels that of multi-centricity, and does not usually progress or change clinical outcome.  For strong advocates for total thyroidectomy, the most compelling argument for performing such an operation in the vast majority of the patients with well-differentiated thyroid cancer depends on the data that come from the definition of prognostic factors for the disease.  Therefore, in high-risk patients, it is preferable to do a near total thyroidectomy. These are candidates for postoperative radioiodine.  In general, with a tumor size >1.0 cm lobectomy and isthmusectomy are satisfactory, but still categorized as low-risk. , Pulmonary metastasis is frequently detected by radioiodine scanning.  The study reported that the rate of these metastases with negative chest radiographs increased from 13% to 43% with the identification of the metastasis by radioiodine. However, no modality can detect all cases of lung metastasis. ,, This solitary metastasis with a long disease-free interval (>12 months) may be resected with good results. 
In our case, the patient was initially expected to have the potential for a malignant course, considering her rapid presentation with dysphagia, dyspnea and hoarseness with increasing tumor size. Postoperatively though, our patient was considered as low-risk according to the Ames, AGES, Macis, EORTC or TNM risk classification system. Interestingly, she developed regional lymph node metastasis 2 years after the initial diagnosis and her lung metastasis came after a prolonged latent period of 24 years. Another unusual aspect of the lung metastasis in this patient is the observation that most lung metastases are usually multiple and sub-centemetric in size. It is rare to find a single metastatic nodule with the size reported in this patient. Papillary thyroid cancer metastasis should be considered in the differential diagnosis of a patient presenting with a solitary lesion in which there is a history of previous papillary thyroid carcinoma.
Several approaches can be undertaken: thoracotomy or video-assisted thoracoscopic surgery. , The standard thoracotomy approach is the posterolateral, with an excellent exposure of the hemithorax.  The only disadvantage is that one hemithorax is explored per operation if nodules are bilateral. The presence of thyroid tissue in the lung parenchyma raises the possibility of either heterotopic thyroid tissue or metastasis from the gland. The follicular variant of papillary cancer has the higher incidence of metastasizing in the lung. Nevertheless, many authors have reported that there is no significant difference in the rate of metastasis compared with the classical papillary carcinoma.  This fact emphasizes the importance of making an early, accurate diagnosis of this unique tumor, and even for its metastatic foci.
| Conclusion|| |
Papillary thyroid cancer is the commonest type of differentiated thyroid neoplasms. Distant metastasis to the lung is rare, and metastasis to lung is usually multiple. We recommend a long close follow-up for papillary thyroid cancer. Solitary pulmonary nodule with a background of papillary thyroid cancer should raise the suspicion of primary lung lesion or papillary metastasis, which can be investigated and managed none invasively.
| Acknowledgment|| |
The authors would like to thank Dr. Eman Al-Dhafeer for collecting the data and references.
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[Figure 1], [Figure 2], [Figure 3]