Papillary thyroid carcinoma (PTC) belongs to well-differentiated thyroid cancers. It is the most common of all thyroid cancers and is among the most curable cancers. Clinically, PTC presents as asymptomatic thyroid nodules, it is usually single, firm, freely moveable during swallowing, and it is not distinguishable from a benign nodule. Thyroid nodule should be suspected of being a carcinoma when it is found in children or adolescents or in patients above 60 years, and when there is a history of increase in size. Histologically, PTC is an unencapsulated tumor with papillary and follicular structures. It is characterized by changes in cell nuclei: nuclear overlapping, large sized nuclei, a ground glass appearance, longitudinal nuclear grooves, and invaginations of cytoplasm into the nuclei. The tumor spreads through the lymphatic vessels within the thyroid, to the regional lymph nodes, and less frequently to the lungs. About 10% of papillary carcinomas are completely surrounded by a dense fibrous capsule. Exposure to external radiation to the neck increases the risk of developing thyroid cancer. Intravenous exposure to radiation for medical tests and treatments, however, does not increase the risk of developing thyroid cancer.
The annual incidence rate of PTC in different parts of the world varies from 0.5-10 per 100,000 populations. The tumor most often occurs in individuals aged 20-50 years. In adults, the female-to-male ratio is 3:1; whereas, in children, the tumor is distributed by sex nearly equally. However, females have a better overall prognosis. Papillary thyroid carcinoma occurs more often in whites than in blacks.
Between 1963 and 1974, El-Ghamrawi and Khalifa (1979) recorded 117 patients with thyroid cancer, who were seen at a tertiary hospital in Kuwait. These 117 patients constituted 4.7% of all cancer cases among females, and 2.4% among males. Papillary carcinoma was seen in 58% of the patients, followed by follicular (25%), and anaplastic (11%), and medullary (1.7%). The 10-year survival rates of these sub-types were calculated to be 74% for papillary, 96% for follicular, and 21% for anaplastic tumors.
Memon et al. (2004) studied 313 case-control pairs in Kuwait to determine an association between family history of benign thyroid disease (BTD) and thyroid or other cancers with an increased risk of thyroid cancer. About a quarter of the subjects with thyroid cancer reported a family history of BTD, while only one eighth of the controls reported such a family history. Individuals with a mother, sister, or aunt affected with BTD had an almost 2-fold risk of developing thyroid cancer. Interestingly, this risk increased significantly with the number of affected female relatives. Family history of thyroid cancer was reported by nine of the cases and three controls. No association was found with family history of any other common cancer.
Pinto and Mathew (1997) examined an Omani, 55-year-old woman, with right sided thyroid swelling of 2 years duration. Physical examination, ultrasound, thyroid scan, needle aspiration, thyroid function test, cytological test, and histological test were performed to confirm the condition, which was histologically classified as papillary thyroid carcinoma, based on the nuclear appearance (ground-glass and grooved), rare psammoma bodies, and the ill-formed papilla in a small part of the tumor nodule. The gradual to sharp transition of follicles with nuclear features of papillary carcinomas raised the possibility that this carcinoma originated from adenomas through clonal evolution. A large area of calcification with cholesterol cleft and ossification was presented in the centre of the tumor. The patient had right hemithyroidectomy. She was followed upon during two years and showed no metastasis (no recurrence), and the thyroglobulin levels remained within the normal range. The absence of lymph node metastasis was attributed to the encapsulated pattern of the papillary carcinoma.
Elshafie et al. (2000) presented a 48-year old Omani lady, who developed adult respiratory distress syndrome after embolization of thyroid cancer metastasis. She was diagnosed with papillary carcinoma for which subtotal thyroidectomy was performed when she was 23-years old. The carcinoma, however recurred 13 years later and she was re-operated upon. She had another recurrence after five years, when she presented with neck swelling (operated) and a vertebral metastasis (decompressed by external radiotherapy). Four years later, she complained of a lump on her head and radiological investigations revealed large metastasis in the skull, spine, sacrum, and mediastinum, for which she received three doses of radioactive iodine (7.95, 5.6, and 8.6 GBq) over the period of three years. As the sacral metastasis continued to grow as seen on radiology and body scintigraph, and was causing severe pain, it was managed by its embolization with gelfoam fragments and a coil was placed in each supplying artery (three branches from internal iliac artery and the right fourth lumbar artery) and she was discharged in a good condition on the fourth day postoperatively. She was readmitted after a week with respiratory distress (cyanosis, tachypnea, and tachycardia) and crepitation in both lungs with no fever or evidence of cardiac failure. Chest X-ray revealed widespread consolidation in both lungs, especially the right. Echocardiography showed good left ventricular function with ejection fraction of 58% and serial ECGs were unchanged. Her serum thyroglobulin (Tg) level increased from 3057ng/ml (before last radioactive iodine) to 428500 ng/ml. She was managed with oxygen, diuretics, antibiotics, and intravenous fluids, and was discharged after a month when the chest X-ray returned to the appearance of pre adult respiratory distress syndrome. Upon follow up after two months, she was pain-free, Tg serum level dropped to 11000 ng/ml, and CT scan revealed necrotic areas in the sacral mass with a reduction of the tumor volume. One year later, her Tg levels increased again, and she died during subsequent radiotherapy. Elshafie et al. (2000) explained her ARDS as a result of precipitation of Tg aggregates in her pulmonary microcirculation and therefore, advised enough hydration several weeks after the procedure of embolization of thyroid carcinoma metastases along with monitoring the Tg levels.
Jyothi et al. (2003) described an 11-year old boy with a diffuse sclerosing variant of papillary thyroid carcinoma. The patient presented with a firm anterior neck swelling on the left side of the thyroid. Tc-99 perthyroid scintigraphy showed cold nodules in the left lobe of the thyroid, while fine needle aspiratipon cytology of this lobe showed a few cells with nuclear grooves, intranuclear cytoplasmic inclusion, psammoma bodies, squamoid cell clusters, and scanty colloid. Upon examination of the left lobe after removal, it was found to be slightly nodular. Microscopic examination revealed diffuse stromal sclerosis, diffuse infiltration by lymphocytes, and most strikingly, the presence of several psammoma bodies. Total thyroidectomy with bilateral functional neck dissection was performed. Biopsy of the right lobe showed similar features to the left. The extra capsular soft tissue was found to be infiltrated by the tumor. In addition, one cervical lymph node on the right and 18 on the left side had metastases. The tumor cells were positive for thyroglobulin and cytokeratin.
Bener et al. (2008) retrospectively studied the Qatar National Cancer Registry to assess the trend in various cancer incidences in Qatar. Thyroid cancer was diagnosed in 31 Qatari patients between 1991 and 1996, 49 Qataris between 1997 and 2001, and in 44 Qataris between 2002 and 2006.
Al-Nuaim et al. (1996) undertook a study of all patients referred to a tertiary care hospital in Riyadh with a diagnosis of thyroid cancer over a period of 3-years (1989-1992). Of the 246 such patients, 233 (94% of them Saudis) had papillary cancer. Such an extremely high representation of papillary thyroid cancer over follicular is characteristic of iodine sufficient areas. Females were over-represented at 79%. Family history of thyroid disease was reported for some of the patients. At the time of presentation, 15 patients had distant metastasis. Analyzing the pattern of age distribution showed that the male patients were more than a decade older than female patients at the time of diagnosis. Of the patients, an extremely high proportion (75%) had capsular and/or soft tissue invasion, indicating aggressiveness and/or late presentation. Findings at second surgery showed significant residual disease.