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Parathyroid carcinoma: Surgical Anatomy and Operative technique Dr R Botha Moderator: Prof JHR Becker Parathyroid carcinoma: • The gold standard therapy of parathyroid cancer is en bloc resection of the primary lesion: Parathyroidectomy Ipsilateral thyroid lobectomy • Prophylactic neck dissection of the central compartment. • Modified radical neck dissection only if positive LN. • Unfortunately the diagnosis is often only made during or after surgery has been completed. Central compartment LN dissection: • Reported incidence of central LN metastasis during initial treatment of parathyroid cancer ranges from 8.1 – 17.9% in the literature. • Due to the absence of alternative curative approaches a systematic dissection of the central LN compartment should be recommended as part of the initial surgery in all patients with suspected parathyroid cancer. KM Schulte et al World J Surgery (2010) 34:2611-2620 Lateral compartment neck dissection: • “ The indication for a lateral compartment resection must be considered more critically. In our opinion there is clearly no indication for lateral neck dissection in parathyroid cancer in the absence of demonstrable suspicious or proven findings.” KM Schulte et al World J Surgery (2010) 34:2611-2620 INCISION: Skin incision: • The incision is made through the skin, subcutaneous tissue and platysma. Superficial cervical fascia: • Fatty connective tissue between the dermis and the investing layer of deep cervical fascia. • Contents: Cutaneous nerves, blood and lymphatic vessels, superficial LN, platysma (anterolateral) and variable amounts of fat. EXPOSURE: • Kelly clamps are placed onto the deep dermal layer with vertical retraction of the flap with countertraction with the surgeons’ finger to expose a natural bloodless plane. • A subplatysmal plane is created superiorly to the uppermost aspect of thyroid cartilage and inferiorly to the level of the suprasternal notch and clavicular heads. • Avoid injury to the anterior jugular veins. • Identify the SCM muscles. Infrahyoid muscles: • Separate the sternohyoid muscles in the midline from thyroid cartilage to suprasternal notch. • Retract the sternohyoid and sternothyroid muscles laterally and separate the infrahyoid muscles from the underlying thyroid lobe with blunt dissection. MOBILIZATION: • The thyroid lobe is mobilized from lateral to medial. • Middle thyroid vein is identified and divided between clamps and tied with 3.0 silk sutures. • This permits full medial rotation of the thyroid lobe. INSPECTION: Parathyroid gland anatomy: Parathyroid glands: • 85% of parathyroid glands are found within 1cm of where the RLN crosses the inferior thyroid artery. • Superior parathyroid glands are located posterior and inferior parathyroid glands are located anterior to the RLN. • Carefully inspect and palpate the thyroid, parathyroid glands and posterior tissue for abnormalities. Operative findings of possible parathyroid carcinoma: • Lobulated firm to stony hard parathyroid mass. • Parathyroid gland is surrounded by a dense fibrous grayish white capsule. • Capsule adheres to adjacent tissue making it difficult to separate from surrounding structures. • Infiltration of the adjacent thyroid, nerve, muscle or esophagus. • Cervical lymphadenopathy. Shane; JCE & M Vol. 86(2):485-493 Frozen section: • Frozen section is not helpful to distinguish between benign and malignant disease. • Excisional biopsy is not recommended due to the risk of intraoperative seeding of tissue leading to parathyromatosis. • Surgeons do not recognize the presence of cancer in as high as 25% of cases. • Carcinoma of multiple glands has been documented in three cases, emphasizing the importance of four gland exploration at initial operation. Sharretts et al. Seminars in Oncology 37(6) 580-590 EN BLOC DISSECTION: Improve exposure: • Elevate the superior flap in the subplatysmal plane to the level of the hyoid bone. • Divide the infrahyoid muscles as high as possible to improve exposure and avoid injury to branches of the ansa cervicalis. • Excise a portion of the infrahyoid muscle with the specimen, to ensure an adequate margin, if the parathyroid mass invades or is tightly adherent to the adjacent muscle. • Avoid intraoperative rupture of the capsule which increases the likelihood of seeding. Superior pole: • Pull superior pole anteriorly and inferiorly. • Sweep areolar tissue away on lateral and medial side of the superior pole. • Isolate superior pole vessels, clamp and ligate. • Avoid injury to external branch of the superior laryngeal nerve. Superior laryngeal nerve: Cernea classification: Inferior pole: • Usually the inferior pole blood vessels must be divided as close as possible to the thyroid to prevent injuring the blood supply to the parathyroid glands. • When performing an en bloc dissection the ipsilateral superior and inferior parathyroid glands will be removed with the specimen. Recurrent laryngeal nerve: Recurrent laryngeal nerve: Recurrent laryngeal nerve: • The most consistent position of RLN is where it enters the larynx on the posterolateral aspect of the cricothyroid muscle at the level of the cricoid cartilage. • If associated scarring and inflammation around the thyroid is present: identify nerve in inferior aspect of neck. • Sacrifice RLN if involvement with carcinoma. Recurrent laryngeal nerve: • Do not use electrocautery near the RLN as it may arc and injure the nerve. • Perform the dissection from the anterolateral surface of the trachea, through Berry’s ligament, carefully as this is the most common site if injury to the RLN. Isthmus: • Create a plane between the isthmus and anterior surface of the trachea. • Divide isthmus on medial border of the contralateral lobe between two Dandy clamps. • Obtain haemostasis of the isthmus with a running suture. CENTRAL NECK LYMPHNODE DISSECTION: • Landmarks: Hyoid bone superiorly, suprasternal notch inferiorly, carotid sheath laterally with trachea medially. • Remove all tracheoesophageal, paratracheal and upper mediastinal lymph nodes in a systematic manner. • Expose entire length of RLN removing adjacent LN. • Only remove RLN or superior laryngeal nerve if involved. HAEMOSTASIS: • Irrigate operative field and obtain haemostasis. • Do not use electrocautery near the RLN. • Be careful not to incooperate the RLN into a tie. • Always visualize the RLN before ligation of a bleeding vessel. • Drain CLOSURE: • Reapproximate the sternohyoid muscles with interrupted sutures. • Close platysma with absorbable 4.0 sutures. • Closure of skin. Role of LN dissection in diagnosis during the early postoperative period: • Re-exploration is indicated if: Gross characteristics of lesion were typical of parathyroid carcinoma Pathology appears to be aggressive with extensive vascular or capsular invasion or The patient remains hypercalcaemic Shane; JCE & M Vol. 86(2):485-493 Role of LN dissection in diagnosis during the early postoperative period: • Simple resection may be curative (no reexploration indicated) if: Absence of above signs Diagnosis is made on microscopic characteristics Carefully observe these patients with PTH and serum calcium levels. Shane; JCE & M Vol. 86(2):485-493 References: • • • • • • • Clinical presentation, staging and long-term evolution of parathyroid cancer. Talat et al. Ann Surg Oncol (2010) 17:2156-2174. The influence of intraoperative parathyroid hormone monitoring on the surgical management of hyperparathyroidism. Mandell et al. Arch Otolaryngol Head Neck Surg Vol 127 July 2001. Lymph Node involvement and surgical approach in parathyroid cancer. Schulte et al. World journal of Surgery (2010) 34:2611 – 2620. Parathyroid cancer. Sharretts et al. Seminars in oncology, Vol 37(6) Dec 2010, 580590. Parathyroid carcinoma encountered after minimally invasive focused parathyroidectomy may not require further radical surgery. O’Neill et al. Worl Journal of Surgery (2011) 35:147-153. Parathyroid carcinoma. Clinical review 122. Shane et al; The Journal of Clinical Endocrinology and Metabolism Vol. 86(2):485- 493. The surgical strategy and the molecular analysis of patients with parathyroid cancer. Keisuke et al. World Journal of Surgery (2010) 34:2604 – 2610.