Friday, April 1, 2011

Introduction to Pediatric Thyroid Cancer

Although a review of thyroid cancer literature contains numerous reports on the subject of pediatric thyroid carcinoma, the low incidence and subsequent lack of prospective randomized trials make drawing absolute conclusions regarding the definitive workup, management, and treatment of this disease difficult.

A detailed understanding of how to perform a comprehensive evaluation of the pediatric thyroid nodule is necessary in order to establish the diagnosis of pediatric thyroid cancer. The incidence of head and neck malignancies, including those of the thyroid, has increased 25% during the past 30 years. 

Although the incidence of thyroid nodules in children is rare before adolescence (1.5%), pediatric thyroid nodules have a 26.4% mean risk of cancer. Some authors have reported an incidence of as high as 36%. Moreover, pediatric thyroid nodules are 4 times more likely to carry a diagnosis of thyroid cancer than adult nodules. Because pediatric thyroid nodules carry this increased risk of malignancy, physicians should perform an expeditious workup.

The recommended diagnostic protocol of thyroid nodules consists of the following steps:
  • Child's history, including the prior existence and treatment of a benign thyroid disease
  • Clinical examination
  • Laboratory tests
  • Thyroid ultrasonography
  • Fine-needle aspiration biopsy (FNAB)

The beneficial role of scintigraphy is limited, and molecular marker analysis is currently more beneficial in a clinical research setting.

Most childhood thyroid nodules are asymptomatic and are detected by parents or by physicians during routine examination. Only about 50% of children with thyroid carcinoma present with nodular thyroid enlargement as the presenting symptom. Follicular adenoma is the most common cause of solitary thyroid nodules in the pediatric population; however, solitary nodules in children reportedly have a 20-73% incidence of malignancy.

Hurthle Cell Carcinoma 
A monomorphous cell population of Hürthle cells arranged in loosely cohesive clusters and single cells. The cells are polyhedral and have abundant granular cytoplasm with well-defined cell borders. The nuclei are enlarged and have a central prominent macronucleolus.  
A painless non-inflammatory metastatic cervical mass is the presenting symptom in 40-60% of patients. Malignant thyroid  lesions in children with no family history of thyroid cancer are usually papillary and follicular carcinomas. Radiation exposure, which is still used either as therapy prior to bone marrowtransplantation or as a treatment of Hodgkin disease, remains a major riskfactor.

The subsequent diagnostic workup is aimed at determining whether the lesion represents a malignancy. Collected data can be useful in preoperative planning if surgery is indicated. Pediatric and adult thyroid cancers have differing biological behaviors. 

Despite the fact that pediatric thyroid cancer usually presents at an advanced stage, it carries an excellent prognosis for most patients.

Author: Mark E Gerber, MD, FACS, FAAP  Clinical Assistant Professor of Otolaryngology, University of Chicago, Pritzker School of Medicine; Section Head, Pediatric Otolaryngology-Head and Neck Surgery, NorthShore University HealthSystem 

Co-Author: Brian Kip Reilly, MD  Assistant Professor of Otolaryngology and Pediatrics, Department of Otolaryngology, Children's National Medical Center, George Washington University School of Medicine 

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