Investigation of a Solitary Thyroid Nodule Dr. Sam Bugis Endocrine Surgery
Investigation of a Solitary Thyroid Nodule Dr. Sam Bugis Endocrine Surgery St. Paul’s Hospital Solitary Thyroid Nodule Palpable solitary thyroid nodules occur in about 5% of the population The harder you look, the more you find Solitary Thyroid Nodule Prevalence • Females >> Males • Increases with age • May vary by geographic location • Increases with exposure to ionizing radiation Solitary Thyroid Nodule Prevalence by Clinical Palpation • Vander et al, Ann Int Med 1968 – 4.2% overall – 6.4% of women – 1.5% of men • Turnbridge et al, Clin Endocrinol 1977 – 3.2% overall Solitary Thyroid Nodule Solitary Thyroid Nodule Prevalence by Ultrasound • 50% of the population will have one or more thyroid nodules seen on U/S Mazzaferri, NEJM 1993 • Only 6% of 1 cm nodules are palpable • Only 50% of 1-2cm nodules are palpable • Even 50-60% of >2 cm nodules are not detected clinically Brander et al, J Clin Ultrasound 1992 Solitary Thyroid Nodule Prevalence by Ultrasound U/S identifies multiple nodules in 16%-48% of clinically solitary nodules Tan et al, Ann Intern Med 1997 Brander et al, J Clin Ultrasound 1992 Walker et al, Br J Radiol 1985 Solitary Thyroid Nodule Prevalence by Autopsy • 49.5% incidence of nodules at least 1 cm in a study of 821 palpably normal thryoid glands • 35% of nodules > 2cm were not identified by palpation • 4.2% were malignant Mortensen et al, J Clin Endocrinol 1955 Solitary Thyroid Nodule Differential Diagnosis • Colloid nodule • Adenoma – Non functioning – Functioning • Cancer – Primary – Metastatic • Cyst – Mixed – True • Thyroiditis • All the rest Indications For Thyroid Surgery (286 Patients) SPH Jan 1/2001-Aug 30/2004 Cancer Suspicion of Cancer 43% 16% Goiter Cyst Hyperthyroidism 6% 20% 1% 5% 5% 4% Subclinical Hyperthyroidism Completion Thyroidectomy Parathyroid Disease Final Pathological Diagnosis in 125 Patients Operated on for Suspicion of Cancer Benign 72% 3% Follicular Carcinoma Papillary Carcinoma 12% 1% 12% Microscopic Focus Papillary Carcinoma (<1cm) Lymphoma Solitary Thyroid Nodule • • • • Indications for Surgery Malignancy Compressive symptoms Recurrent nodules Hyperthyroidism • Clinical • Sub-clinical • Cosmesis Investigation of a Solitary Thyroid Nodule 5% of solitary thyroid nodules are cancer How do we find them? Investigation of a Solitary Thyroid Nodule Assessment of risk FNAB Other investigations Investigation of a Solitary Thyroid Nodule Investigation of a Solitary Thyroid Nodule Clinical Risk Factors • • • • • • Age Sex Symptoms Physical findings Family history Radiation history Investigation of a Solitary Thyroid Nodule • • • • Symptoms Hoarseness Dysphagia Hemoptysis Rapid growth Physical findings • Hard, fixed • Lymphadenopathy • RLN palsy • Single vs multiple Investigation of a Solitary Thyroid Nodule Family History Familial non-medullary thyroid cancer (NMTC) • Up to 5% of non-medullary cancers • 2 (or 3) direct relatives without other syndromes • More aggressive than sporadic disease • 2 types: Papillary >>> Hurthle cell Investigation of a Solitary Thyroid Nodule Family History Familial adenomatous polyposis • Females age 25-35 at highest risk • Disease is multifocal and bilateral Cowden disease • Hamartomas at various sites • Cancers of thyroid and breast Investigation of a Solitary Thyroid Nodule Family History Familial Medullary Thyroid Cancer (MTC) • 25% of all MTC • Familial MTC alone or in MEN syndromes • Ret oncogene point mutation on chromosome 10 • Recommendations for management Investigation of a Solitary Thyroid Nodule Radiation Exposure • External irradiation to the neck in childhood increases risk of benign and malignant thyroid nodules • Risk is greatest in those exposed at the youngest age • Risk increases linearly up to 1500 cGy • Females are at greater risk than males • Many controversies about screening and follow up Investigation of a Solitary Thyroid Nodule • TSH • FNAB as part of the physical exam • +/- Ultrasound • +/- Nuclear Scan • +/- CT, MRI Investigation of a Solitary Thyroid Nodule What is the role of Ultrasound for a palpable solitary thyroid nodule? “the ultrasound machine to the endocrinologist evaluating a thyroid nodule is analogous to the stethoscope of the cardiologist” Weiss and Lado-Abeal, Curr Opin Oncol 2003 Investigation of a Solitary Thyroid Nodule What is the role of Ultrasound for a palpable solitary thyroid nodule? • To confirm the thyroid as the tissue of origin • As a guide to FNAB for a mass that is difficult to feel • To objectively measure size in patients being followed with or without thyroid suppression • For follow up/screening in patients with radiation exposure Investigation of a Solitary Thyroid Nodule • 80-90% of all nodules • 10-20% are cancers • Routine use is not indicated • 5% or less of all nodules • <1% are malignant • Used in patients with suppressed TSH to identify toxic adenoma • Also used in indeterminate FNAB Investigation of a Solitary Thyroid Nodule CT and MRI • No role in routine investigation • In patients with established cancers or large goiters, can assess involvement of surrounding structures, retrosternal extension and status of cervical lymph nodes Investigation of a Solitary Thyroid Nodule Thyroid Suppression • Remains controversial • Studies have suffered from: • • • • Non randomization Heterogeneous groups Inadequate TSH monitoring Inaccurate measurement Investigation of a Solitary Thyroid Nodule Thyroid Suppression • Meta analyses suggest a trend toward nodule shrinkage in treatment groups • Overall, only 10%-20% of nodules respond • Which patients? • Predominantly solid nodules • ? Abundant colloid • ? Other factors • Recognize risks • Cardiac effects • Effects on bone metabolism Thyroid Incidentaloma Thyroid Incidentaloma Thyroid Incidentaloma Definition: a nodule(s) unexpectedly identified during an unrelated imaging investigation or procedure • Ultrasound is the commonest culprit • Generally non palpable and < 1.5 cm Thyroid Incidentaloma “The thyroid is normal in size, the right lobe measuring 3.2 x 2.0 x 1.5 cm. The left lobe measures 3.4 x 1.8 x 2.1 cm and the isthmus is 5 mm” “In the right lobe are 3 nodules, one cystic, the others mixed, with maximum diameters of 3 mm, 7 mm and 9 mm. There are 2 similar nodules on the left side” Thyroid Incidentaloma “Cannot differentiate adenoma from carcinoma, suggest nuclear medicine scan and/or fine needle biopsy.” Thyroid Incidentaloma Who gets investigated? • Size > 1.5 cm • Clinical risk factors Thyroid Incidentaloma Who gets investigated? • Family history • MTC • NMTC • Radiation exposure • One nodule 1.3 cms Æ FNAB • Multiple nodules Æ observe +/- U/S or FNAB Thyroid Incidentaloma Who gets investigated? Ultrasound features of malignancy • Hypoechoic • Irregular • Microcalcifications • Intra nodular vascularity • Incomplete halo Thyroid Incidentaloma What size nodules and how many should be targeted? • 1.5 cm or larger – by consensus • 1.0 cm or larger – ? arbitrary • 0.8 cm or larger – Papini, J Clin Endocrinol Metab 2002 • Up to 3 nodules – ? arbitrary Investigation of a Solitary Thyroid Nodule Radiation Exposure • All patients with childhood exposure should be followed – the question is how? • Clinically normal thyroid • Regular exam, possibly U/S every 1-3 yrs • Clinically palpable nodule(s) Æ FNAB • Multiple nodules – follow up exam only, +/U/S, +/- FNAB, +/- surgery Palpable solitary thyroid nodule Normal TSH Risk factor assessment Cold FNAB Benign Non Dx Suspicious Suppressed TSH Nuclear scan Malignant Hot FNAB Treat re size and hyperthyroidism or Observe Repeat If follicular, +/- U/S +/- U/S Consider nuclear Surgery scan for low risk +/- Thyroxine Consider risk Hot Cold assessment Treat as above Non palpable thyroid incidentaloma > 1.5 cms U/S guided FNAB U/S features Benign Observe Malignant U/S guided FNAB < 1.5 cms Low risk High risk Observe Physical exam Follow up U/S U/S guided FNAB -up to how many -down to what size Solitary Thyroid Nodule Prevalence by Autopsy Conversely, 100% of thyroid glands dissected at 2.5 mm intervals had papillary cancer Harach et al, Cancer 1985
© Copyright 2024