Distinguishing Intrathyroid Parathyroid Adenoma from Colloid Nodules and Papillary Thyroid Carcinomas Using Multiphasic Multidetector Computed Tomography.

OBJECTIVE: The aim of the study is to determine whether multiphase multidetector computed tomography (4D-MDCT) can differentiate between intrathyroid parathyroid adenomas (ITPAs), colloid nodules, and papillary thyroid carcinoma (PTC). METHODS: We studied 22 ITPAs, 22 colloid nodules, and 11 PTCs in 55 patients. Hounsfield unit (HU) values of the nodules were measured on 4D-MDCT in the precontrast, arterial, venous, and delayed phases. Raw HU values, phase with peak enhancement, and washout percentages between the phases were evaluated. RESULTS: Regardless of size, all ITPAs (22/22) showed peak enhancement in the arterial phase, which was significantly greater than both colloid nodules (15/22) and PTC (6/11, P = 0.002); thus, nodules with peak enhancement in the venous or delayed phase were not ITPAs (specificity = 1). For nodules with peak enhancement in the arterial phase, the percentage washout in the arterial-to-venous phases separated ITPAs from PTC and colloid nodules (P < 0.001) with greater than or equal to 23.95% loss of HU value implying IPTA (area under curve, 0.79). This left a subset of colloid nodules or PTC that either peaked in the venous or delayed phase or had an arterial-to-venous phase washout of less than 23.95%. From this subset, PTC measuring 1 cm or greater could be separated from colloid based on HU values in the arterial phase with a cutoff HU value less than 81.4 for PTC (area under curve, 0.72) and an HU value greater than 164.5 suggested colloid. CONCLUSIONS: Intrathyroid parathyroid adenomas can be distinguished from colloid nodules and PTC by peak enhancement in the arterial phase and rapid washout. A subset of colloid and PTC measuring 1 cm or greater can be separated using arterial phase HU values.

Multifocal recurrence of pleomorphic adenoma of the lacrimal gland.

Purpose: To report two cases of multifocal recurrent pleomorphic adenoma of the lacrimal gland, and to highlight the clinical and magnetic resonance imaging findings. Observations: The authors present two patients with recurrent pleomorphic adenoma of the lacrimal gland. During their previous primary surgical resection at outside institutions, one patient reportedly had a macroscopically complete excision, while the second patient had violation of the pseudocapsule. Both patients had multiple recurrent nodular lesions detected on magnetic resonance imaging with extension beyond the surgical field of the primary resection. Both underwent subsequent lateral orbitotomy with resection of all identifiable nodules and histopathology was consistent with pleomorphic adenoma. In one patient, two nodules were found two months after the surgery, which grew slowly over the last four years. The second patient had no clinical or radiologic sign of recurrence at last follow up, three years after resection of multinodular recurrence. Conclusions and importance: The two cases demonstrate the challenges in the management of multifocal recurrence of lacrimal gland pleomorphic adenoma. The multicentric nature of recurrent lesions in these two cases increase the risk of future recurrence, malignant transformation, and morbidity caused by surgery and radiation. Magnetic resonance imaging is the imaging study of choice, but it may still be inadequate in identifying all the nodules.

Clinical and cytopathological features of suspected thyroglossal duct cysts and neoplasms arising from them: A large series from a referral cancer center.

BACKGROUND: Thyroglossal duct cysts (TGDCs) are the most common congenital midline cystic lesions in the neck, and they are often evaluated by fine-needle aspiration. Recognizing the cytomorphologic features of TGDCs and their mimics is important for clinical management. METHODS: This study examined the clinical, radiological, and cytopathological features of 86 ultrasonography-guided fine-needle aspiration (US-FNA) specimens from clinically suspected TGDCs or malignancies arising from TGDCs and correlated the findings with surgical follow-up and/or imaging studies. RESULTS: According to ultrasound examinations of 66 lesions, 17 (25.8%) were cystic, 8 (12.1%) were cystic with septations, 21 (31.8%) were cystic with solid nodules, and 20 (30.3%) were solid or cystic with internal debris. Cytopathologically, 81 lesions (94%) were categorized as benign, 2 (2%) were categorized as atypical, and 3 (3%) were categorized as malignant. In benign lesions, proteinaceous material (63%), histiocytes (63%), colloid (37%), squamous cells (35%), columnar cells (32%), follicular cells (15%), inflammatory cells (9%), and multinucleated giant cells (9%) were noted. Diagnoses in the benign category included TGDC in 64 patients (75%), TGDC or mimics (colloid nodule/epidermoid cyst) in 14 patients (17%), a colloid nodule in 1 patient, and thyroiditis in 1 patient. Surgical resection, performed in 23 patients, confirmed TGDCs in 12, benign mimics in 7, and carcinoma in 4. CONCLUSIONS: Cytopathological features, in conjunction with imaging, allowed a definite diagnosis of TGDC in most patients (75%). The presence of mature squamous cells, thyroid follicular cells, with or without colloid and/or lymphocytes alone allowed a differential diagnosis of TGDC and its mimics in 17%. US-FNA findings could not distinguish primary carcinomas arising from TGDCs from metastatic tumors.

Frequency and Clinical Course of Residual Orbital Masses After Treatment of Orbital Rhabdomyosarcoma.

PURPOSE: To evaluate the frequency and clinical course of residual orbital masses on imaging studies after multimodality treatment for orbital rhabdomyosarcoma. DESIGN: Retrospective case series. METHODS: We reviewed records of patients with primary orbital rhabdomyosarcoma who underwent chemotherapy and radiotherapy after surgical biopsy or debulking at 4 US centers during 1998-2019. Demographics, histologic subtype, tumor response 12 weeks after chemotherapy initiation and after completion of all treatment, and imaging findings were analyzed. RESULTS: Thirty-two patients met inclusion criteria. Twenty-two were male, and 30 were younger than 18 years. Histologic subtype was embryonal in 22 patients, alveolar in 8, and mixed embryonal/alveolar in 2. Median follow-up time was 46 months (range, 4.9-199 months). Two patients died. Twenty-seven patients had reliable end-of-treatment imaging findings, of whom 9 had a residual mass. Three residual masses disappeared spontaneously (by 4, 32, and 53 months), 2 remained at last contact, at 2 and 7 years of follow-up, and 3 were excised; 1 progressed and underwent an exenteration. Complete response at 12 weeks was associated with complete response at the end of treatment (P < .001). Patients with T1 or T2 tumor at presentation were more likely to have complete response at last contact than were those with T3 or T4 tumor (P < .05). Biopsy type (incisional or excisional) was not associated with response to treatment at any time point. CONCLUSION: A residual orbital mass on imaging may be present after multimodality treatment in approximately one-third of patients. Resolution without biopsy or excision varied from months to years.

Primary Ewing's sarcoma with orbit involvement: Survival and visual outcomes after eye-sparing multidisciplinary management in eight patients.

BACKGROUND: To describe the clinical presentation, treatment, and overall prognosis in eight patients with primary Ewing's sarcoma (ES) involving the orbit. METHODS: A retrospective interventional study of all biopsy-proven cases of primary ES involving the orbit was done. RESULTS: There were seven males and one female with a median age of 14 years. Imaging showed osseous involvement in all eight cases with extraorbital extension in four. Complete tumor resection was done in four, partial resection in three, and biopsy followed by sinus surgery in one. EWSR1 gene rearrangement analysis was done to confirm diagnosis. All patients received multidrug systemic chemotherapy and seven patients received adjuvant radiotherapy. Eye salvage was achieved in all patients. At a mean follow-up duration of 52.63 months, seven patients were doing well with no evidence of disease. CONCLUSIONS: ES involving the orbit is sensitive to chemotherapy and radiation. Aggressive multimodality treatment can help salvage the globe and improve overall survival.

Primary disease sites and patterns of spread in cases of neurolymphomatosis in the orbit associated with lymphoma.

BACKGROUND: Neurolymphomatosis involving the cranial nerves (CNs) is rare. We sought a better understanding of the primary disease sites and patterns of spread in neurolymphomatosis of the orbit and retro-orbital cranial nerves. METHODS: Patients with lymphoma and MRI evidence of neurolymphomatosis of CN II, III, IV, V1, or V2 were retrospectively reviewed. Demographics and primary disease site and sites of neurolymphomatosis on MRI were recorded. Wilcoxon rank sum test was used to compare number of sites of neurolymphomatosis with lymphoma type and survival. RESULTS: The study included 18 patients. The most frequent types of lymphoma were diffuse large B-cell (DLBCL) (n = 9) and marginal zone (n = 3). In 9 patients, lymphoma presented as a mass (n = 7) or infiltrative disease (n = 2) directly involving the orbit; in 6, a maxillofacial mass spread directly to CNs; and in 3, lymphoma at remote sites spread to orbital CNs. Overall, 81 sites of neurolymphomatosis were noted. The most common sites were the maxillary nerve (V2) including at the infraorbital fissure or foramen rotundum (17 patients; 19 nerves), pterygopalatine fossa (16 patients; 19 nerves), and cavernous sinus (9 patients; 12 nerves). Number of sites of neurolymphomatosis was significantly lower for DLBCL than for other lymphoma types (p = 0.007). Number of sites of neurolymphomatosis did not affect survival (p = 0.26). The mean interval between the pathologic diagnosis and MRI documentation of the full extent of neurolymphomatosis was 39 days after pathologic diagnosis. CONCLUSIONS: Based on our study results, neurolymphomatosis in the orbit appears to be frequently associated with an orbital and/or maxillofacial mass and commonly involves CN V2, the pterygopalatine fossa, and the cavernous sinus. DLBCL may be associated with fewer sites of neurolymphomatosis than other lymphomas. In patients with lymphoma, a systematic search for neurolymphomatosis is imperative for early detection.

A modular phantom and software to characterize 3D geometric distortion in MRI.

Magnetic resonance imaging (MRI) offers outstanding soft tissue contrast that may reduce uncertainties in target and organ-at-risk delineation and enable online adaptive image-guided treatment. Spatial distortions resulting from non-linearities in the gradient fields and non-uniformity in the main magnetic field must be accounted for across the imaging field-of-view to prevent systematic errors during treatment delivery. This work presents a modular phantom and software application to characterize geometric distortion (GD) within the large field-of-view MRI images required for radiation therapy simulation. The modular phantom is assembled from a series of rectangular foam blocks containing high-contrast fiducial markers in a known configuration. The modular phantom design facilitates transportation of the phantom between different MR scanners and MR-guided linear accelerators and allows the phantom to be adapted to fit different sized bores or coils. The phantom was evaluated using a 1.5 T MR-guided linear accelerator (MR-Linac) and 1.5 T and 3.0 T diagnostic scanners. Performance was assessed by varying acquisition parameters to induce image distortions in a known manner. Imaging was performed using T1 and T2 weighted pulse sequences with 2D and 3D distortion correction algorithms and the receiver bandwidth (BW) varied as 250-815 Hz pixel-1. Phantom set-up reproducibility was evaluated across independent set-ups. The software was validated by comparison with a non-modular phantom. Average geometric distortion was 0.94 ± 0.58 mm for the MR-Linac, 0.90 ± 0.53 mm for the 1.5 T scanner, and 1.15 ± 0.62 mm for the 3.0 T scanner, for a 400 mm diameter volume-of-interest. GD increased, as expected, with decreasing BW, and with the 2D versus 3D correction algorithm. Differences in GD attributed to phantom set-up were 0.13 mm or less. Differences in GD for the two software applications were less than 0.07 mm. A novel modular phantom was developed to evaluate distortions in MR images for radiation therapy applications.

Malignant Mixed Tumor (Carcinoma Ex Pleomorphic Adenoma) of the Lacrimal Gland.

PURPOSE: To review the clinical presentation, treatment, and prognosis of patients with malignant mixed tumor (carcinoma ex pleomorphic adenoma) of the lacrimal gland. METHODS: Clinical records and radiographic images were reviewed for patients with malignant mixed tumor of the lacrimal gland treated at the center during 2008-2019. RESULTS: The study included 9 patients (6 men, 3 women) aged 17-66 years (median age, 56 years). Six had primary malignant mixed tumor with no history of orbital lesions, and 3 had previously been diagnosed with pleomorphic adenoma. Tumor, Node, Metastasis classification per the eighth edition of the American Joint Committee on Cancer (AJCC) Cancer Staging Manual were T1aN0M0 in 2 patients, T2aN0M0 in 3 patients, T4bN0M0 in 2 patients, and T4cN0M0 in 2 patients. Two patients underwent orbital exenteration, 6 patients underwent eye-sparing surgery, and 1 patient had an unresectable tumor because of cavernous sinus extension. All patients received radiotherapy (intensity-modulated radiotherapy in 3 and proton therapy in 6). All patients received chemotherapy, 8 concurrently with radiotherapy and 1 after radiotherapy. The median follow-up time was 70 months. At last contact, 6 patients were alive without evidence of disease; 2 had died of disease, 1 of distant metastasis, and the other of cavernous sinus invasion. CONCLUSIONS: The findings suggest that de novo malignant mixed tumor of the lacrimal gland is more common than disease that results from transformation after incomplete resection of lacrimal gland pleomorphic adenoma. Most cases can be treated with eye-sparing surgery and radiation unless skull base extension is present.

Vascular flow on doppler sonography may not be a valid characteristic to distinguish colloid nodules from papillary thyroid carcinoma even when accounting for nodular size.

BACKGROUND: The purpose of this study was to test the hypothesis that there is no significant difference in vascular flow patterns between cytopathologically-proven colloid nodules and papillary thyroid carcinoma (PTC) even when adjusting for nodule size. METHODS: Doppler vascular flow patterns in 200 colloid nodules and 166 nodules with PTC were retrospective reviewed independently by 2 neuroradiologists blinded to the cytopathological results. Absence of vascular flow, perinodular and/or intranodular flow, and diffuse vascular flow were recorded. The vascular flow patterns were compared without (Fisher exact test) and with (Kruskal-Wallis test) an adjustment for nodular size. Using the most common flow pattern as the reference group, multiple logistic regression was used to compare the flow patterns. Sample skewness was calculated to determine degree of symmetry of the size distribution for each vascular flow category. RESULTS: No significant difference was found in the tested vascular flow patterns between colloid nodules and PTC both without and with an adjustment for nodular size (P>0.05). Intranodular flow only was the largest group (n=111/366) and used as the reference for multiple logistic regression. No significant difference was noted between the vascular flow patterns (P>0.05). Sample skewness showed that nodules were generally smaller in size with outliers of larger size on the opposite end of the spectrum. CONCLUSIONS: Independent of nodule size the absence or presence of vascular flow is not significantly different between colloid nodules and PTC. Therefore, vascular flow may not be useful in distinguishing between colloid nodules and PTC.

Radiographic retropharyngeal lymph node involvement in HPV-associated oropharyngeal carcinoma: Patterns of involvement and impact on patient outcomes.

BACKGROUND: The objective of the current study was to characterize the incidence, pattern, and impact on oncologic outcomes of retropharyngeal lymph node (RPLN) involvement in HPV-associated oropharyngeal cancer (OPC). METHODS: Data regarding patients with HPV-associated OPC who were treated at The University of Texas MD Anderson Cancer Center with intensity-modulated radiotherapy from 2004 through 2013 were analyzed retrospectively. RPLN status was determined by reviewing pretreatment imaging and/or reports. Outcomes analysis was restricted to patients with lymph node-positive (+) disease. Kaplan-Meier survival estimates were generated and survival curves were compared using the log-rank test. Bayesian information criterion assessed model performance changes with the addition of RPLN status to current American Joint Committee on Cancer staging. Competing risk analysis compared modes of disease recurrence. RESULTS: The incidence of radiographic RPLN involvement was 9% (73 of 796 patients) and was found to vary by primary tumor site. The 5-year rates of freedom from distant metastases (FDM) and overall survival were lower in patients with RPLN(+) status compared with those with RPLN-negative (-) status (84% vs 93% [P = .0327] and 74% vs 87% [P = .0078], respectively). RPLN(+) status was not found to be associated with outcomes on multivariate analysis. Bayesian information criterion analysis demonstrated that current American Joint Committee on Cancer staging was not improved with the inclusion of RPLN. Locoregional and distant disease recurrence probabilities for those patients with RPLN(+) status were 8% and 13%, respectively, compared with 10% and 6%, respectively, for those with RPLN(-) status. RPLN(+) status portended worse 5-year FDM in the low-risk subgroup (smoking history of <10 pack-years) and among patients who received concurrent chemotherapy but not induction chemotherapy. CONCLUSIONS: RPLN(+) status was associated with worse overall survival and FDM on univariate but not multivariate analysis. In subgroup analyses, RPLN(+) status was associated with poorer FDM in both patients with a smoking history of <10 pack-years and those who received concurrent chemotherapy, suggesting that RPLN(+) status could be considered an exclusion criteria in treatment deintensification efforts seeking to omit chemotherapy.

Extraocular Muscle Enlargement and Thyroid Eye Disease-like Orbital Inflammation Associated with Immune Checkpoint Inhibitor Therapy in Cancer Patients.

PURPOSE: To describe thyroid eye disease (TED)-like orbital inflammatory syndrome in 3 cancer patients treated with immune checkpoint inhibitors. METHODS: All consecutive patients treated by the senior author who were receiving immune checkpoint inhibitors and developed TED-like orbital inflammation were included. RESULTS: Three cancer patients treated with immune checkpoint inhibitors developed orbital inflammation. The first patient was treated with a combination of a cytotoxic T-lymphocyte antigen-4 inhibitor and a programmed cell death protein 1 inhibitor and developed TED-like orbital inflammation with normal thyroid function and antibody levels. The second patient had a previous diagnosis of Graves disease without TED, and developed TED soon after initiating treatment with a programmed cell death protein 1 inhibitor. The third patient developed acute hyperthyroidism with symptomatic TED following treatment with an investigational cytotoxic T-lymphocyte antigen-4 inhibitor agent. All 3 patients were managed with either systemic steroids or observation, with resolution of their symptoms and without the need to halt immune checkpoint inhibitor treatment for their cancer. DISCUSSION AND CONCLUSIONS: TED-like orbital inflammation may occur as a side effect of immune checkpoint inhibitor therapy with anti-cytotoxic T-lymphocyte antigen-4 or anti-PD-1 inhibitors. To the best of their knowledge, this is the first reported case of TED as a result of programmed cell death protein 1 inhibitor monotherapy. All 3 patients were treated with systemic steroids and responded quickly while continuing treatment with immune checkpoint inhibitors for their cancer. With increasing use of this class of drugs, clinicians should be familiar with the clinical manifestations and treatments for this adverse reaction.

A prospective in silico analysis of interdisciplinary and interobserver spatial variability in post-operative target delineation of high-risk oral cavity cancers: Does physician specialty matter?

BACKGROUND: The aim of this study was to determine the interdisciplinary agreement in identifying the post-operative tumor bed. METHODS: Three radiation oncologists (ROs), four surgeons, and three radiologists segmented post-operative tumor and nodal beds for three patients with oral cavity cancer. Specialty cohort composite contours were created by STAPLE algorithm implementation results for interspecialty comparison. Dice similarity coefficient and Hausdorff distance were utilized to compare spatial differentials between specialties. RESULTS: There were significant differences between disciplines in target delineation. There was unacceptable variation in Dice similarity coefficient for each observer and discipline when compared to the STAPLE contours. Within surgery and radiology disciplines, there was good consistency in volumes. ROs and radiologists have similar Dice similarity coefficient scores compared to surgeons. CONCLUSION: There were significant interdisciplinary differences in perceptions of tissue-at-risk. Better communication and explicit description of at-risk areas between disciplines is required to ensure high-risk areas are adequately targeted.

Clinical Presentation and Anatomical Location of Orbital Plasmacytomas.

PURPOSE: To evaluate the clinical and anatomical location of orbital plasmacytomas and assess local control following therapy. METHODS: The American Society of Ophthalmic Plastic and Reconstructive Surgery Oncology Database was queried to identify patients diagnosed with orbital plasmacytoma. These patients' records were reviewed for demographic characteristics, clinical and radiologic findings, treatments, and outcomes. RESULTS: Thirty patients from 4 institutions (24 from MD Anderson Cancer Center, 3 from SUNY Downstate Medical Center, 2 from University of California, Los Angeles, and 1 from Oregon Health and Science University) were identified. Eighteen patients (60%) were diagnosed with multiple myeloma (MM) before and 11 (37%) were diagnosed with MM immediately after orbital plasmacytoma. Based on imaging, 4 distinct anatomical patterns were identified: 1) bony plasmacytoma affecting the superotemporal orbit, epidural space, and temporal fossa (15 patients; 50%); 2) discrete orbital plasmacytoma (7 patients; 23%); 3) infiltrative plasmacytoma either originating from a sinus (4 patients; 13%); or 4) originating from the orbital floor and infiltrating facial soft tissue (4 patients; 13%). Of the 29 patients with available treatment data, 2 had radiation only, 3 had chemotherapy only, 6 had chemoradiation, and 18 had stem cell transplant following chemoradiation (n = 17) or only chemotherapy (n = 1). Following treatment, 10 patients achieved complete and 11 achieved partial responses. CONCLUSION: Orbital plasmacytomas were found exclusively in patients with MM diagnosed before or immediately after orbital plasmacytoma. Plasmacytomas can have 4 distinct anatomical patterns of origin. Following treatment, all patients had good to excellent local control of their orbital lesions.

Most common sites on MRI of intracranial neoplastic leptomeningeal disease.

Neoplastic leptomeningeal disease (LMD) represents infiltration of the leptomeninges by tumor cells. Knowledge of the frequencies of locations of LMD on MRI may assist in early detection, help elucidate the process of leptomeningeal spread of cancer and understand how LMD affects the central nervous system. Our goal was to identify intracranial sites of neoplastic LMD predilection on MRI in patients with cytologically-proven LMD. The presence of FLAIR signal hyperintensity and T1-weighted post-contrast enhancement in the sulci of the supratentorial compartment and cerebellum and enhancement of the cranial nerves (CNs), basal cisterns, pituitary stalk, and ependymal surface of the lateral ventricles, as well as the presence of parenchymal metastasis were recorded. Within each imaging sequence, sites were ordered by prevalence and compared using McNemar's test. The study included 270 patients. Positive MRI findings were present in 185/270 (68.5%) patients. FLAIR signal hyperintensity was significantly more common (p≤0.003) in the cerebellum (n=96) and occipital lobe (n=92) relative to the other lobes. Leptomeningeal enhancement was also significantly more common (p≤0.009) in the cerebellum (n=82) and occipital lobe (n=67) relative to the other lobes. Enhancement was most commonly found involving CN VII/VIII and the ependymal surface of the lateral ventricles compared to other sites. Parenchymal metastases were present in 110 (40.1%) of the patients. In conclusion, neoplastic LMD predominantly involves the cerebellum and occipital lobes, CN VII/VIII, and the ependymal lining of the lateral ventricles. Parenchymal metastases are frequently present in patients with neoplastic LMD.

Rates of Positive Findings on Positron Emission Tomography and Bone Marrow Biopsy in Patients With Ocular Adnexal Lymphoma.

PURPOSE: The aim of this study was to determine rates of positive findings on positron emission tomography (PET) and bone marrow biopsy performed during staging workup for ocular adnexal lymphoma (OAL). METHODS: A retrospective review of OAL patients was conducted. Demographics, primary versus secondary OAL, histologic subtype, and findings on PET and bone marrow biopsy performed as part of the initial staging workup for OAL were recorded. RESULTS: The study included 119 patients with OAL. There were 85 primary and 34 secondary OALs. The main histologic subtypes of lymphoma were mucosa-associated lymphoid tissue (n = 61), follicular (n = 26), diffuse large B-cell (n = 17), and mantle cell (n = 10). Positive PET findings were seen in 42 of 68 patients (62%) with primary OAL and 19 of 24 (79%) with secondary OAL. Positive PET findings were seen in 24 of 47 patients (51%) with mucosa-associated lymphoid tissue, 13 of 17 (76%) with follicular, 14 of 15 (93%) with diffuse large B-cell, and 9 of 10 (90%) with mantle cell lymphoma. Positive findings on bone marrow biopsy were seen in 7 of 59 patients (12%) with mucosa-associated lymphoid tissue, 4 of 23 (17%) with follicular, 1 of 17 (6%) with diffuse large B-cell, and 2 of 9 (22%) with mantle cell lymphoma. CONCLUSIONS: Our findings suggest that a significant proportion of patients with primary and secondary OAL have positive findings on PET and bone marrow biopsy at initial diagnosis, suggesting a reasonable yield for these tests as part of the initial staging workup in patients with a new diagnosis of OAL.

18F-PET/CT imaging of metastasis to the thyroid gland: Imaging findings and effect on patient management.

PURPOSE: While metastasis to the thyroid from a primary cancer remote to the thyroid is uncommon, current imaging techniques have improved detection of these intrathyroid metastases. The purpose of this study was to evaluate the 18F-PET/CT appearance of intrathyroid metastases and assess the impact of detection on patient management. METHODS: The 18F-PET/CT appearance of intrathyroid metastasis, including standardized uptake value (SUV), disease extent, and the effect on patient management following diagnosis were retrospectively reviewed. Inclusion criteria included 18F-PET/CT imaging and diagnosis of the intrathyroid metastasis matching the remote primary tumor. RESULTS: Intrathyroid metastasis were detected in 24 patients. The intrathyroid metastases presented on 18F-PET/CT as focal nodular uptake (n = 21), multiple nodular uptake (n = 2), or diffuse uptake/infiltration of the thyroid gland (n = 1). The SUV ranged between 3.9 and 42 (median 12.5 ± 7.5); in 2 patients, the FDG-avidity was minimal. On 18F-PET/CT, distant metastases were present outside the neck (n = 18), or limited to the neck (n = 6). In 2 of these 6 patients, the thyroid was the only site of metastatic disease. Due to the metastatic disease, the therapy was changed in 23 of 24 patients; 1 patient was lost to follow-up. CONCLUSION: In any patient with a previous or current history of an extrathyroid malignancy, an 18FDG-avid thyroid mass or diffuse infiltration of the thyroid on 18F-PET/CT should be considered a potential intrathyoid metastasis until proven otherwise. Knowledge of an intrathyroid metastasis may impact patient management, especially if the thyroid or neck are the only sites of metastatic disease.

Sonographic Evaluation of Intrathyroid Metastases.

OBJECTIVES: Intrathyroid metastases from extrathyroid primary tumors are rare. Clinical findings may be subtle, but detection of intrathyroid metastases has improved with sonography. The objective of this study was to evaluate the sonographic appearance of intrathyroid metastases. METHODS: Patients with thyroid masses with cytopathologic features matching those of an extrathyroid primary tumor were retrospectively identified. The appearances of intrathyroid metastases on sonography were reviewed for the following features: size, margin regularity, echogenicity, echotexture, vascularity on power or color Doppler ultrasonography, and the presence or absence of any associated cervical adenopathy. RESULTS: The study included 52 patients. The most frequent primary tumor sites were lung, head and neck, and breast. Intrathyroid metastases presented as a discrete nodule in 34 patients and as diffuse infiltration of the gland in 18 patients. The discrete nodules ranged in size from 1.1 to 5.6 cm (mean ± SD, 2.5 ± 1.2 cm). Thirty-three lesions (63%) had irregular margins, and 19 (37%) had well-defined margins. Most of the lesions were heterogeneously hypoechoic (n = 50, 96%). Vascularity was present in 32 of 50 measured lesions (64%) that were evaluated with Doppler sonography. Cervical adenopathy was present in 37 patients (71%). CONCLUSIONS: Intrathyroid metastases have sonographic characteristics similar to those described for both benign and malignant thyroid diseases. In patients with a previous or current extrathyroid malignancy, thyroid nodules or diffuse infiltration of the thyroid gland on sonography should be viewed as a potential intrathyroid metastasis and evaluated via ultrasound-guided fine-needle aspiration regardless of the site of the primary tumor.