Do medullary thyroid carcinoma patients with high calcitonin require bilateral neck lymph node clearance? A case report

Table 1 Clinical and pathological data of the patient

Project	Content
Biographical data	53 years old and female
Family history	No
Chief complaint	Thyroid nodule discovered 2 mo prior
Specialized physical examination	The trachea was in the middle. The thyroid gland moved up and down with swallowing action, and no nodules were felt in the bilateral lobes. There was no hoarseness in the voice and no choking cough when drinking water.
US	Nodules were found in bilateral lobes of the thyroid gland, and the right lobe had a well-defined hypoechoic nodule with a size of approximately 10 mm × 6 mm. The left lobe had a cystic and solid mixed hypoechoic nodule with a size of approximately 22 mm × 11 mm. The US grade was TI-RADS 4. Multiple solid hypoechoic nodules were detected in bilateral I-IV areas of the neck, and the boundaries of the medulla and cortex were not clear
CEUS	Lymph nodes were observed on both sides of the neck. T-CEUS suggested that the cortical stage of the lymph nodes was enhanced by uneven medulla, while the medulla was slightly enhanced. Enlarged lymph nodes were considered as reactive hyperplasia
FNAC	Right thyroid nodule was suspected as a thyroid papillary carcinoma (TBSRTC V). Left thyroid nodule cytology suggested a malignancy (TBSRTC V), but the type was not determined
Surgery	Thyroidectomy, bilateral central lymph node dissection, and bilateral recurrent laryngeal nerve exploration
Frozen pathology	Bilateral papillary thyroid micropapillary carcinoma and bilateral central lymph nodes showed no cancer metastasis
Paraffin pathology	Left medullary thyroid carcinoma (Figure 2), with immunohistochemistry results of calcitonin (+), CK (+), TTF1 (+), CK19 (-), thyroglobulin (-), galectin-3 (-), Ki -67 < 1%, and MC (-); right thyroid papillary carcinoma, BRAF V600E mutation
Final diagnosis	Papillary thyroid carcinoma of the right lobe (T1N0M0, stage I) and medullary thyroid carcinoma of the left lobe (T1N0M0, stage I)
Postoperative treatment	Oral levothyroxine sodium tablets (Euthyrox): 100 µg/time/day

CEUS: Contrast-enhanced ultrasonography; TTF1: Thyroid transcription factor; FNAC: Fine needle aspiration cytology; TI-RADS: Thyroid imaging reporting and data system; TBSRTC: The Bethesda system for reporting thyroid cytopathology.

Table 2 Postoperative follow-up monitoring

Time	CT (pg/mL)	TSH (μIU/mL)	TgAb (IU/mL)	Tg (ng/mL)	CEA (µg/L)
Normal	< 6.4	0.5-4.8	0-115	3.5-77	< 3.0
Preoperative	345	4.2	< 10.0	16.820	/
1 d after surgery	15.74	2.545	< 10.0	3.370	6.440
1 wk after surgery	2.69	0.634	< 10.0	0.497	/
1 mo after surgery	0.84	0.096	14.4	0.062	/
2 mo after surgery	0.55	0.048	14.0	0.040	/
5 mo after surgery	< 0.5	0.473	< 10.0	0.040	/
8 mo after surgery	< 0.5	0.343	< 10.0	0.110	< 3.0
1 yr after surgery	< 0.5	0.343	< 10.0	0.100	< 3.0
1.5 yr after surgery	< 0.5	0.008	< 10.0	0.100	1.18

CT: Calcitonin; TSH: Thyroid-stimulating hormone; TgAb: Anti-thyroglobulin antibody; Tg: Thyroglobulin; CEA: Anti-carcinoembryonic antigen.

Table 3 Risk classification of medullary thyroid carcinoma patients based on genetic mutations (2015 version of United States thyroid association)

Risk classification	Patient population	Treatment
ATA-HST	MEN2B; RET codon M918T mutation	Thyroidectomy ± central lymph node dissection in the neck within 1 year after birth
ATA-H	MEN2A; RET codon C634 mutation	Five years old or earlier thyroidectomy ± central lymph node dissection
ATA-MOD	Others	Every year from the age of 5, physical examination, neck US, and serum calcitonin

MTC: Medullary thyroid carcinoma; ATA: United States thyroid association; RET: Reticulocytes; HST: Hubble space telescope; MOD: Medicine on delivery; US: Ultrasound.

Table 4 Cervical lymph node clearance range

Condition	Treatment
Patients without evidence of cervical lymph nodes and distant metastases before surgery	Preventive central lymph node dissection
Preoperative calcitonin 40-150 pg/mL, even if no suspected lymph node metastasis were found	Central lymph node and ipsilateral II-IV lymph node dissection
Patients with preoperative calcitonin > 200 pg/mL	Ipsilateral neck II-VI lymph node dissection, and contralateral cervical lymph nodes should also be considered for removal