You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is Lymphatic spread is most commonly seen in which type of thyroid malignancy: and explain in detail?
Ans. a. Papillary carcinoma (Ref: Robbins 9/1096, 8/1121-1122, Schwartz 9/1361-1363: Sabiston 19/906-909; Bailey 26/765-768, 25/793-796; Harrison 18/2936)Papillary Carcinoma of ThyroidAccounts for 80% of all thyroid malignancies in iodine-sufficient areasQMC thyroid cancer in children and individuals exposed to external radiationQ.More often in women, 30-40 years.Pathology:Grossly: Hard and whitish and remain flat on sectioning with a blade with macroscopic calcification, necrosis, or cystic changesMultifocalityQ is common (up to 85% of cases) on microscopic examination.Multifocality is associated with an increased risk of cervical nodal metastasesQ, rarely invade adjacent structures such as the trachea, esophagus, and RLNs.Rarely encapsulatedQ (PCT are seldom encapsulated)Other variants: Tall cellQ, insularQ, columnar, diffuse sclerosing, clear cell, trabecular, and poorly differentiated types: account for about 1%; associated with a worse prognosis.Histological characteristics of Papillary Carcinoma ThyroidPapillary projectionsQ: PTC contains branching papillae of cuboidal epithelial cellsOrphan Annie eye nuclei:The nuclei contain finely dispersed chromatin, which imparts an optically clear or empty appearance, giving rise to term ground glass or Orphan Annie eye nucleiQInvaginations of cytoplasm in cross-sections: Intranuclear inclusionsQ (pseudoinclusion) or intranuclear groovesQ.Diagnosis of PTC is based on these nuclear characteristicsQ even in the absence of papillary structures.Psammoma bodiesQ: Microscopic, calcified deposits representing dumps of sloughed cellsClinical Features:Most patients are euthyroid and present with a slow-growing painless massQ in the neck.Dysphagia, dyspnea & dysphonia are associated with locally advanced invasive disease.Lymph node metastases are commonQ, especially in children and young adults, and may be the presenting complaint."Lateral aberrant thyroid" almost always denotes a cervical lymph node that has been invaded by metastatic cancerQ.Distant metastases are uncommon at initial presentation, but may ultimately develop in up to 20% of patients.The MC sites of metastasis: LungsQ >bone >liver >brain.Diagnosis:Diagnosis is established by FNAC of the thyroid mass or lymph nodeQ.Once thyroid cancer is diagnosed on FNAC, a complete neck ultrasound to evaluate the contralateral lobe and for LN metastases in the central & lateral neck compartments.Treatment: Total or near-total thyroidectomyQDuring thyroidectomy, enlarged central neck nodes should be removedQBiopsy-proven lymph node metastases detected clinically or by imaging in the lateral neck in patients with papillary- carcinoma are managed with modified radical neck dissection.Prognosis:PTC have an excellent prognosis with a >95% 10-year survival rateQ.