Explanation:

In patients with differentiated thyroid carcinoma (DTC), elevated serum thyroglobulin (Tg) levels and a negative whole-body iodine-131 scan suggest the presence of recurrent or metastatic disease that is no longer iodine-avid, a phenomenon referred to as "iodine-refractory disease." In such cases, 18F-FDG PET/CT is a highly valuable imaging modality due to its ability to detect metabolically active lesions that do not take up iodine. This imaging technique leverages the increased glucose metabolism of de-differentiated thyroid cancer cells, which exhibit high uptake of fluorodeoxyglucose (FDG). Studies have shown that 18F-FDG PET/CT has high sensitivity (up to 93%) and specificity (up to 95%) for detecting recurrent or metastatic DTC in patients with elevated Tg levels and negative radioiodine scans. Additionally, it provides precise anatomical localization, which can guide further management decisions, such as surgery or external beam radiation therapy. Option a: Incorrect. Residual thyroid tissue in the thyroid bed is better evaluated using ultrasound or iodine scintigraphy, not FDG PET/CT.

Option c: Incorrect. Differentiating benign from malignant nodules is typically achieved through fine-needle aspiration biopsy and cytology, not FDG PET/CT.

Option d: Incorrect. The functional status of the thyroid gland is assessed using laboratory tests (e.g., TSH, free T4) and iodine uptake studies, not FDG PET/CT.

Option e: Incorrect. FDG PET/CT does not determine the need for additional radioiodine therapy; it identifies lesions that are refractory to iodine uptake and may require alternative treatments such as surgery or systemic therapy.

Further Reading:

Dong MJ, Liu ZF, Zhao K, et al. Role of fluorodeoxyglucose-PET versus PET/computed tomography in detection of recurrent or metastatic differentiated thyroid carcinoma: A meta-analysis of eight studies including 222 patients. Thyroid Journal, 2010;20(10):1097-1103.

Miller ME, Chen Q, Elashoff DA, et al. Positron emission tomography-computed tomography in the management of differentiated thyroid cancer: An evidence-based review and analysis of its impact on patient management and outcomes. Thyroid Journal, 2012;22(3):234-241.

Treglia G, Sadeghi R, Schalin-Jäntti C, et al. Diagnostic performance of fluorine-18-fluorodeoxyglucose positron emission tomography in patients with suspected recurrent medullary thyroid carcinoma: A meta-analysis and systematic review. Endocrine Journal, 2015;49(1):1-10.

Additional Concepts:

Iodine-Refractory Thyroid Cancer:

Iodine-refractory DTC occurs when tumor cells lose their ability to concentrate iodine due to de-differentiation, making radioiodine therapy ineffective. This condition is associated with worse prognosis and often necessitates alternative therapeutic strategies such as systemic therapies (e.g., tyrosine kinase inhibitors) or external beam radiotherapy.

Thyroglobulin as a Tumor Marker:

Serum Tg levels are a sensitive marker for detecting residual or recurrent DTC after total thyroidectomy and radioiodine ablation therapy. Rising Tg levels in the absence of iodine uptake on imaging strongly suggest persistent disease.

Flip-Flop Phenomenon in Imaging:

The "flip-flop" phenomenon refers to an inverse relationship between iodine uptake and FDG avidity in DTC cells: well-differentiated tumors typically show high iodine uptake but low FDG uptake, while poorly differentiated tumors exhibit low iodine uptake but high FDG uptake.

Role of TSH Stimulation in Imaging:

TSH stimulation enhances FDG uptake by increasing glucose metabolism in thyroid cancer cells through upregulation of GLUT1 transporters and glycolysis pathways, improving the sensitivity of FDG PET/CT for detecting recurrent or metastatic disease.

These concepts are critical for understanding advanced diagnostic approaches in managing challenging cases of differentiated thyroid cancer and preparing for board examinations effectively.

Explanation:

This complex case requires recognition of multisystem sarcoidosis with critical ocular involvement. The combination of parotid enlargement (present in 2-6% of sarcoidosis cases), uveitis, and radiographic/biological evidence of systemic disease necessitates immediate immunosuppression. Corticosteroids remain first-line therapy for active sarcoidosis affecting multiple organ systems, particularly when vision-threatening manifestations exist. Why other options are incorrect: NSAIDs (a): Adequate only for isolated arthralgias or erythema nodosum, not for visceral/organ-threatening disease

Parotidectomy (c): Reserved for refractory cases with mass effect after failed medical management (recurrence rates >50% without systemic control)

Hydroxychloroquine (d): Considered adjunctive therapy for cutaneous/hypercalcemic manifestations but insufficient for acute ocular inflammation

Observation (e): Contraindicated with progressive organ involvement - 30-50% of patients with ocular sarcoidosis develop permanent vision loss without treatment Additional Concepts: Biopsy Strategy: Minor salivary gland biopsy has 58-70% sensitivity for systemic sarcoidosis versus 90% for parotid biopsy, but the latter carries higher complication risks. Concurrent conjunctival biopsy increases diagnostic yield in ocular cases.

ACE Level Utility: Elevated in 41-75% of active systemic cases but normal in 25% of isolated parotid presentations. Serial measurements help monitor treatment response.

Radiographic Staging: Bilateral hilar lymphadenopathy (Stage I) carries 55-90% spontaneous resolution rates versus 10-20% in Stage III (parenchymal disease). Ocular involvement necessitates treatment regardless of radiographic stage.

Extrapulmonary Patterns: Uveoparotid fever (Heerfordt syndrome) classically combines parotid enlargement, uveitis, and cranial neuropathies. Lacrimal gland involvement occurs in 19-38% of parotid cases, requiring vigilant dry eye management.

Further Reading:

Ungprasert P, Crowson CS, Matteson EL. Clinical Characteristics of Parotid Gland Sarcoidosis. J Clin Med. 2016;5(5):45.

Judson MA, Baughman RP. Diagnosis and Detection of Sarcoidosis. Am J Respir Crit Care Med. 2020;201(8).

Arkema EV, Cozier YC. Sarcoidosis epidemiology: recent estimates of incidence, prevalence and risk factors. Curr Opin Pulm Med. 2020;26(5):527-533.

Additional Concepts:

Biopsy Strategy: Minor salivary gland biopsy has 58-70% sensitivity for systemic sarcoidosis versus 90% for parotid biopsy, but the latter carries higher complication risks. Concurrent conjunctival biopsy increases diagnostic yield in ocular cases.

ACE Level Utility: Elevated in 41-75% of active systemic cases but normal in 25% of isolated parotid presentations. Serial measurements help monitor treatment response.

Radiographic Staging: Bilateral hilar lymphadenopathy (Stage I) carries 55-90% spontaneous resolution rates versus 10-20% in Stage III (parenchymal disease). Ocular involvement necessitates treatment regardless of radiographic stage.

Extrapulmonary Patterns: Uveoparotid fever (Heerfordt syndrome) classically combines parotid enlargement, uveitis, and cranial neuropathies. Lacrimal gland involvement occurs in 19-38% of parotid cases, requiring vigilant dry eye management.

Explanation:

The superior trapezius myocutaneous flap primarily receives its blood supply from the occipital artery. This artery provides a robust and reliable vascular supply, making it suitable for reconstructive procedures in the head and neck region. While the transverse cervical artery and its branches, such as the superficial cervical artery, also contribute to the blood supply of the trapezius muscle, the occipital artery is specifically noted for its role in the superior portion of the muscle.

The supraclavicular artery and superficial temporal artery are not primary suppliers of the trapezius muscle. The subclavian artery is a major artery that gives rise to several branches, including the transverse cervical artery, but it is not the direct blood supply to the superior trapezius flap.

Further Reading:

Mathes SJ, Nahai F. Reconstructive Surgery: Principles, Anatomy, and Technique. Churchill Livingstone, 1997; 1: 1-20.

McCraw JB, Magee WP Jr. Trapezius myocutaneous flap: its uses in head and neck reconstruction. Plastic and Reconstructive Surgery. 1976; 57(1): 49-57.

Urken ML. Atlas of Regional and Free Flaps for Head and Neck Reconstruction. Raven Press, 1995; 1: 1-20.

Additional Concepts:

Anatomical Variations: The blood supply to the trapezius muscle can vary significantly among individuals. The transverse cervical artery and dorsal scapular artery often have a reciprocal relationship, with one being dominant in different cases.

Flap Types: The trapezius muscle can be used to create several types of flaps, including superior, lateral island, and extended island flaps. Each type has different applications and limitations based on its vascular supply and mobility.

Surgical Considerations: When raising a trapezius flap, it is crucial to identify and preserve the vascular pedicles to ensure adequate blood supply. The flap's design should consider the patient's anatomy and the specific requirements of the reconstruction site.

Clinical Applications: Trapezius flaps are versatile and can be used for a variety of reconstructive procedures, including defects in the head, neck, and posterior scalp. They offer advantages such as local tissue availability and minimal donor site morbidity.

Explanation:

Progressive visual impairment is a critical indication for surgical intervention in cases of fibrous dysplasia, especially when it involves craniofacial structures like the maxilla, as it can lead to significant morbidity if left untreated89. While aesthetic concerns and discomfort are valid reasons for surgery, they are generally considered secondary to functional impairments such as vision loss. The potential for malignant transformation is low in fibrous dysplasia, making it less compelling as an immediate reason for surgery unless other high-risk features are present. Anxiety about having a mass may influence patient preference but does not constitute a medical necessity on its own.

The wrong options are incorrect because:

Aesthetic concerns (a) and mild discomfort (b) might prompt elective surgery but do not represent urgent medical needs.

Potential for malignant transformation (c) is rare and not typically an immediate concern.

Patient's general anxiety (e) may influence decision-making but isn't a primary clinical indication.

Further Reading:

Valentini V et al., Fibrous Dysplasia: An Overview of Disease Process, Indications for Surgery.

Döhler JR et al., Surgical Treatment Options in Fibrous Dysplasia.

Pamuk AE et al., Juvenile Nasopharyngeal Angiofibroma: Clinical Features and Surgical Outcomes.

Additional Concepts:

1. Juvenile Nasopharyngeal Angiofibroma Recurrence Factors

JNA recurrence is influenced by several factors including tumor size, stage at diagnosis, presence of intracranial extension or sphenoid bone invasion, surgical approach used (with endoscopic approaches generally associated with lower recurrence rates), and intraoperative bleeding volume.

2. Fibrous Dysplasia Management Principles

Fibrous dysplasia management often involves conservative monitoring unless symptoms arise or there's significant deformity or risk to vital structures like vision or hearing pathways68. Radical excision with reconstruction may be necessary in symptomatic cases to prevent complications such as fractures or further disfigurement.

3. Craniofacial Reconstruction Techniques

In cases requiring extensive resection due to conditions like aggressive fibrous dysplasia or large tumors like JNA with intracranial extension, advanced reconstruction techniques involving custom implants can restore both function and aesthetics effectively.

4. Role of Preoperative Embolization

Preoperative embolization can significantly reduce intraoperative blood loss during surgeries involving highly vascular tumors such as JNA but might increase hospital stay duration due to additional procedures required before surgery itself.

Explanation:

The child in this vignette has recurrent AOM (defined as ≥3 episodes in 6 months or ≥4 episodes in 12 months) and persistent middle ear effusion (MEE), evidenced by type B tympanograms and conductive hearing loss on audiometry. Recurrent AOM and chronic MEE significantly impact hearing and quality of life, warranting surgical intervention when medical management fails. Correct Answer (c): Bilateral tympanostomy tube placement

Tympanostomy tubes are the standard of care for children with recurrent AOM or chronic MEE that causes hearing loss or other symptoms such as speech delay or balance issues. Tubes allow ventilation of the middle ear, prevent fluid accumulation, and reduce the frequency of infections.

Incorrect Options:

a. Initiate a 6-month course of azithromycin prophylaxis: Long-term antibiotic prophylaxis is no longer recommended due to concerns about antimicrobial resistance and limited efficacy compared to surgical options.

b. Perform adenoidectomy with bilateral myringotomy: Adenoidectomy is typically reserved for children ≥4 years old or those with significant nasal obstruction or adenoid-related pathology. It may be considered as an adjunct to tympanostomy tubes in refractory cases but is not first-line in this age group.

d. Switch to high-dose amoxicillin during acute episodes: While high-dose amoxicillin is effective for treating individual AOM episodes, it does not address the underlying issue of recurrent AOM and persistent MEE.

e. Continue observation with serial tympanometry: Observation is inappropriate given the frequency of infections, persistent MEE, and associated conductive hearing loss, which can affect speech and language development.

Further Reading:

Le Saux N, Robinson JL; Canadian Paediatric Society, Infectious Diseases and Immunization Committee. Management of acute otitis media in children six months of age and older. Paediatr Child Health. 2016;21(1):39-44.

Hoberman A, Paradise JL, Rockette HE, et al. Treatment of acute otitis media in children under 2 years of age. N Engl J Med. 2011;364(2):105-115.

Rosenfeld RM, Shin JJ, Schwartz SR, et al. Clinical practice guideline: Otitis media with effusion (update). Otolaryngol Head Neck Surg. 2016;154(1 Suppl):S1-S41.

Additional Concepts:

Role of Tympanostomy Tubes in Recurrent AOM: Tympanostomy tubes reduce the frequency of AOM episodes by ventilating the middle ear and allowing drainage of effusions5. They also provide a route for topical antibiotic therapy if infections recur post-placement, minimizing systemic antibiotic use.

Impact of Chronic MEE on Development: Persistent MEE can cause conductive hearing loss, which may impair speech and language development in young children during critical developmental windows25. Early intervention is crucial to mitigate these effects.

Adenoidectomy as Adjunctive Therapy: Adenoidectomy may be considered in children older than 4 years or those with significant adenoid hypertrophy contributing to eustachian tube dysfunction or recurrent infections.

Antibiotic Stewardship in Pediatric AOM Management: Prolonged antibiotic use increases the risk of resistance and adverse effects without significantly reducing recurrence rates compared to surgical interventions like tympanostomy tubes.

This question assesses higher-order clinical decision-making by integrating diagnostic findings, treatment guidelines, and long-term management considerations for recurrent AOM in young children.