Hepatic Superscan in Medullary Thyroid Carcinoma: A Rare Presentation in [¹⁸F]FDG PET/CT

A 65-year-old female with longstanding goiter history and no familial cancer background exhibited intermittent right upper quadrant abdominal pain, nausea, vomiting, and greenish diarrhea. Recurrent dehydration prompted emergency visits, culminating in admission. Initial assessments indicated mild anemia and slightly elevated liver enzymes. In light of clinical presentation, an abdominal magnetic resonance imaging (MRI) revealed substantial hepatomegaly and liver lesions, prompting an ultrasound-guided liver biopsy to exclude malignancy. Pending results, the patient’s condition rapidly worsened, with intensified vomiting after each oral intake.

Given these concerns, the patient was transferred to our cancer center. A multidisciplinary clinic opted for [¹⁸F]fluorodeoxyglucose ([¹⁸F]FDG) positron emission tomography/computed tomography (PET/CT), aiming to identify the primary tumor and stage the disease, pending biopsy results. The results showed a hypermetabolic thyroid lesion (Fig1a, b, d; arrowheads), mediastinal lymph node involvement (Fig1a, c; curved arrows), hepatic superscan (Fig. 1a, d; arrows), and bone marrow lesions (Fig. 1a, e; asterisks). The comprehensive assessment indicated a complex diagnostic scenario, suggesting either multiple primary neoplasms affecting the liver and thyroid or an extensive metastatic thyroid malignancy. Unfortunately, the patient’s condition deteriorated, leading to her death before liver biopsy results confirmed metastatic medullary thyroid carcinoma (MTC). Shortly thereafter, a comprehensive histopathological examination encompassing immunohistochemistry indicated metastatic MTC (Fig. 1f). The examined sections demonstrated positive expression for chromogranin, thyroid transcription factor-1 (TTF-1), and calcitonin immunostains (Fig. 1f).

Fig. 1.

a Maximum intensity projection image revealed evidence of hypermetabolic malignant large left thyroid lobe lesion (arrowhead), associated with few hypermetabolic metastatic mediastinal lymphadenopathy (curved arrow), several hypermetabolic bone marrow lesions (asterisks), and hypermetabolic massive hepatomegaly (i.e., hepatic superscan, arrow). b Axial PET/CT images of the neck revealed evidence of a large left thyroid lobe lesion with a maximum standardized uptake value (SUVmax) of 6.3 (arrowheads). c Axial PET/CT images of the thorax revealed evidence of a few hypermetabolic mediastinal lymph nodes (SUVmax up to 5.1; curved arrows). d Coronal PET/CT image demonstrating evidence of hepatic super scan (SUVmax 19.8; arrow) visualized concurrently with the hypermetabolic malignant left thyroid lobe tumor (arrowhead). e Axial PET/CT images demonstrating evidence of several hypermetabolic bone marrow lesions involving the left humeral shaft, S1 vertebra, and right proximal femur (SUVmax up to 8.1; asterisks). f Histopathologic examination of the ultrasound-guided liver biopsy sample revealed evidence of metastatic medullary thyroid carcinoma evidenced by positive expression for chromogranin, thyroid transcription factor-1 (TTF-1), and calcitonin immunostains

Metastatic MTC primarily spreads via the lymphatic system, often infiltrating cervical lymph nodes in early stages [1]. Distant metastases are infrequent at initial diagnosis, often indicating disease recurrence or progression [1]. The metastatic pattern in MTC resembles that of papillary thyroid carcinoma [2]. A recent study challenges the assumption that lymph node involvement accompanies distant metastases, with 14% of papillary thyroid cancer patients exhibiting N0M1 disease [3]. Our patient showed skip metastases, where lymph nodes bypass nearby ones, deviating from the typical sequence and affecting the next nodal level [4]. The patient also showed a unique pattern of hypermetabolic hepatomegaly, indicating hepatic superscan that has been previously observed in many solid and hematologic malignancies [5].

In conclusion, our case exemplifies the first imaging depiction of a patient with MTC displaying a metastatic hepatic superscan and a skip pattern of metastases, with N0M1 disease. Consequently, nuclear medicine physicians should be aware of this possibility when evaluating patients with hepatic superscan. Furthermore, the absence of local lymph node involvement does not preclude the presence of skip metastases in MTC.

Author Contribution

Ahmed Saad Abdlkadir and Akram Al-Ibraheem participated in the study conception and design. Ahmed Saad Abdlkadir and Dhuha Al-Adhami participated in manuscript initial drafting. Raghad Alhouwari, Ula Al-Rasheed, Omar Jaber, and Akram Al-Ibraheem participated in data collection. Baraa Alsyouf, Raghad Alhouwari, Ula Al-Rasheed, Omar Jaber, Issa Mohamad, and Akram Al-Ibraheem participated in data analysis and interpretation of results. Ahmed Saad Abdlkadir, Ula Al-Rasheed, and Akram Al-Ibraheem participated in manuscript finalization. All authors read and approved the final manuscript.

Data Availability

The current study data are available from the corresponding author upon reasonable request.

Declarations

Conflict of Interest

Ahmed Saad Abdlkadir, Dhuha Al-Adhami, Baraa Alsyouf, Raghad Alhouwari, Ula Al- Rasheed, Issa Mohamad, and Akram Al-Ibraheem declare no conflict of interest.

Ethics Approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Consent to Participate

Informed consent was obtained from the patient.

Consent for Publication

Not applicable.

Declaration of Generative AI in Scientific Writing

The authors did not use any AI software during the preparation of this manuscript.

Preprint Sharig

Not applied.