An unusual presentation of medullary carcinoma of the thyroid gland.
Medullary carcinoma of the thyroid gland stands out from the other thyroid carcinomas due to several peculiarities.,  It is the only thyroid tumour that is familial and which may occur with other endocrinopathies like phaeochromocytoma, hyperparathyroidism, carcinoid and neurofibromatosis.
Its histogenesis is from the `C' cells or parafollicular cells and hence it may secrete thyrocalcitonin which may significantly lower the serum calcium levels.
This case report outlines the diagnostic difficulties and experience in treating a case of medullary carcinoma of thyroid which presented as a huge vascular metastatic lateral neck swelling with an occult thyroid nodule.
A 40 year old female patient presented with a progressively increasing swelling on the left side of the neck of 3 years' duration. There was a history of hoarseness of voice for 6 months prior to admission. There was no history suggestive of a primary malignancy anywhere in the body.
On examination, there was a huge, oval, firm to hard, nodular swelling which was mobile transversely and occupying the entire anterior and posterior triangles of the left side of the neck with an intra-thoracic extension under the clavicle [Fig. 1]. All the midline structures were pushed to the right. Prominent veins were seen over the swelling and the swelling itself gave transmitted pulsations on palpation. The carotid artery pulsations were diminished above the level of the swelling. A bruit was well heard over the swelling. A detailed E.N.T. examination revealed only a left vocal cord palsy. There was no evidence of any primary malignancy. Systemic examination was normal.
As our clinical impression was a malignant lymphonodular mass, most probably a secondary, an attempt was made to locate the primary and the patient was subjected to the following investigations:
A. Plain radiograph of the chest and neck showed changes of chronic bronchitis with a very faint doubtful circular opacity 1/2 cm in diameter in the left upper zone.
B. Barium meal with follow-through was normal.
C. Direct laryngoscopy, bronchoscopy and oesophagoscopy were normal.
D. All routine hematological and biochemical investigations were within normal limits. Serum calcium was normal and blood and urine vanilyl mandelic acid (VMA) were within normal limits.
E. An angiogram [Fig. 2] of the left carotid and subclavian vessels showed a highly vascular tumor mass with tumor blush, pushing the carotids to the right but deriving neo-vascularisation from subclavian and scapular vessels. A small vascular extrapleural chest focus was also seen in the left upper zone.
F. Thyroid scan showed a cold area in the left lobe of the thyroid gland.
G. A biopsy was performed under local anaesthesia and a small bit of the mass was removed from one of the nodules posteriorly. Histopathology of this mass showed small malignant cells of uniform size resembling carcinoid tumor with a typical endocrine arrangement. Tumor emboli were seen in the vessels. There was no stroma containing amyloid. In view of the cold area in the thyroid gland it was thought as metastasis from medullary carcinoma of the thyroid gland (amyloid negative type [Fig. 3].
After the above investigations, the patient was taken up for surgery. Under general anaesthesia, the neck was explored by a long transverse incision, 11/2 above the clavicle. There was a hard nodule in the left lobe of the thyroid gland seperate from the metastasic mass. A subtotal thyroidectomy with left radical neck dissection with removal of entire metastasic mass and removal of intrathoracic extension by excision of middle two thirds of clavicle was done. A small bit of normal thyroid tissue with parathyroids was left behind in the right paratracheal space. Post-operative recovery was uneventful.
A post-operative carotid angiogram showed that the vascular neck mass was absent, but the small extrapleural chest focus was still persistant [Fig. 4]. Histopathology confirmed the diagnosis of medullary thyroid carcinoma. The patient was then subjected to megavoltage deep X-Ray therapy-6000 rads over 6 weeks.
The patient is living and clinically free from recurrence 10 months after surgery. (Last follow up 2 months ago).
Medullary carcinoma of the thyroid gland, although first described in 1951, was initially proposed as a clinical entity by Hazard et at, 1959. Since then over 249 cases have been reported in the English literature. It accounts for 6.8% of the primary thyroid carcinomas. It is slightly more common in females than in males (ratio of 1.3:1) and the average age of presentation is 36 years (30-50 years). It presents as a hard, ill-defined, solid, invasive mass within the thyroid gland. Calcium deposits may be seen. Histologically it is composed of columns or masses of epithelial cells lying in a dense characteristic stroma that stains typically for amyloid. Tumour cells are round, polygonal or spindle shaped and show changes of malignancy. True psammoma bodies may be seen. Metastatic lesions may be difficult to separate from, poorly differentiated cells as amyloid may or may not be present. In 50-67% of cases, the tumor has metastasised to regional lymph nodes at the time of surgery and hence radical node dissection is justifiable in most cases. It usually pursues a low grade course and ultimately metastasises. Medullary carcinomas rarely take up radioiodine so that when complete excision is doubtful megavoltage external irradiation is given with good results in atleast 25% of cases. Sedgwick of Lahey Clinic treats medullary carcinomas with a subtotal thyroidectomy preserving the parathyroids of one side, with a radical node dissection and considers megavoltage external irradiation in cases with metastasis. He also advocates life time thyroid supression therapy.
Prognosis is relatively poor as compared to other differentiated thyroid carcinomas. Beahrs et all have reported an 85% 10 years' survival rate if the tumor is restricted to the thyroid gland and 42% 10 years' survival rate if lymph node metastases are present. Sutten et al have reported 34% 10 years' survival rate in a total of 48 cases. Survival rates are variable indicating that the biology of medullary carcinoma is unpredictable. The prognosis in our case cannot be predicted but remains to be seen.
The authors wish to thank the Dean, Dr. C. K. Deshpande for granting permission to publish hospital data.
We also owe our gratitude to Dr. C. V. Patel, Associate Professor of Surgery, for his valuable assistance prior to and during surgery.
We also thank the Department of Radiology for assisting in the investigations.