Metastases to the parotid nodes: CT and MR imaging findings

Elective parotidectomy and neck dissection are not beneficial in cutaneous squamous cell carcinoma of the head

OBJECTIVE

Cutaneous Squamous Cell Carcinoma (cSCC), a tumor with a significantly increasing incidence, is mostly diagnosed in the head region, where tumors have a worse prognosis and a higher risk of metastases. The presence of metastases reduces specific five-year survival from 99% to 50%. As the risk of occult metastases does not exceed 10%, elective dissection of the tributary parotid and neck lymph nodes is not recommended.

METHODS

We retrospectively analyzed a group of 12 patients with cSCC of the head after elective dissections of regional (parotid and cervical) nodes by means of superficial parotidectomy and selective neck dissection.

RESULTS

We diagnosed occult metastases neither in the cervical nor parotid nodes in any patient. None were diagnosed as a regional recurrence during the follow-up period.

CONCLUCION

Our negative opinion on elective parotidectomy and neck dissection in cSCC of the head is in agreement with the majority of published studies. These elective procedures are not indicated even for tumors showing the presence of known (clinical and histological) risk factors for lymphogenic spread, as their positive predictive value is too low. Elective parotidectomy is individually considered as safe deep surgical margin. If elective parotidectomy is planned it should include only the superficial lobe. Completion parotidectomy and elective neck dissection are done in rare cases of histologically confirmed parotid metastasis in the parotid specimen. Preoperatively diagnosed parotid metastases without neck involvement are sent for total parotidectomy and elective selective neck dissection. Cases of clinically evident neck metastasis with no parotid involvement, are referred for comprehensive neck dissection and elective superficial parotidectomy. The treatment of concurrent parotid and cervical metastases includes total conservative parotidectomy and comprehensive neck dissection.

LEVEL OF EVIDENCE

How common is the problem? Step 4 (Case-series) Is this diagnostic or monitoring test accurate? (Diagnosis) Step 4 (poor or non-independent reference standard) What will happen if we do not add a therapy? (Prognosis) Step 4 (Case-series) Does this intervention help? (Treatment Benefits) Step 4 (Case-series) What are the COMMON harms? (Treatment Harms) Step 4 (Case-series) What are the RARE harms? (Treatment Harms) Step 4 (Case-series) Is this (early detection) test worthwhile? (Screening) Step 4 (Case-series).

Nonbrain metastases seen on magnetic resonance imaging during metastatic brain tumor screening

Although metastases found during head magnetic resonance imaging (MRI) are not limited to metastatic brain tumors, the MRI is a very common method for “brain metastasis screening,” a modality that is being increasingly performed. In this review, we describe MRI findings of nonbrain metastases and discuss ways to avoid missing these lesions. Metastatic cranial bone tumors are among the most common nonbrain metastatic lesions found on head MRI, followed by leptomeningeal carcinomatosis. The other less-frequent metastatic lesions include those in the ventricle/choroid plexus, the pituitary gland and stalk, and the pineal gland. Metastases in the head and neck area, as well as cranial and intracranial lesions, should be carefully evaluated. Furthermore, direct geographical invasion, perineural spread, and double cancers should also be considered. While it is important to recognize these metastatic lesions on MRI, because they may necessitate a change in treatment strategy that could lead to an improvement in prognosis due to early introduction of therapy, nonbrain lesions should also be given greater attention, given the increasing survival of patients with cancer and advances in MRI technology, such as contrast-enhanced-3D T1-weighted imaging.

Metastatic parotid gland malignancy: A preliminary study in an eastern Chinese population

OBJECTIVE

This study aimed to determine the incidence and clinicopathological patterns of metastatic carcinoma of the parotid gland.

METHOD

Ninety patients with parotid gland metastases admitted to our hospital between January 2003 and December 2018 were included in this study. Clinical and pathological data were obtained from the medical records and follow-ups. Kaplan-Meier analysis was used to assess overall survival of patients.

RESULTS

Among the 90 patients, parotid gland metastases originated from the head and neck in 86 (95.6%), from non-head and neck in 4 (4.4%), from the oral cavity in 30(33.3%), and from the eyelid in 21 (23.3%). Among the 85 cases with parotid gland lymph node metastasis, 45 (52.9%) were diagnosed with extra-lymph node metastasis. The capsule of the parotid lymph nodes was thinner than that of the cervical lymph nodes (P < 0.05). Hematogenous metastases to the parotid gland (only five cases) were rare, mainly from the non-head and neck malignancies. Patients with oral squamous cell carcinoma and meibomian adenocarcinoma with parotid metastatic disease had poorer overall survival (P < 0.05).

CONCLUSION

Eastern China population analysis showed that parotid gland metastases usually arise from oral squamous cell carcinoma and eyelid, but rarely from cutaneous squamous cell carcinoma. Most cases metastasize to the parotid lymph nodes via the lymphatic system and are prone to extranodal extension with little or no facial nerve involvement. These findings have important implications for the treatment of metastatic parotid malignancies.

Metastases to the Parotid Gland: Study from a Tertiary Care Centre

BACKGROUND

Metastases account for 6-25% of parotid tumors, often presenting dilemmas in their diagnosis.

METHODS

Parotid metastases diagnosed on histology/cytology were retrieved. MUC2, MUC5AC, androgen receptor immunohistochemistry was performed in select cases.

RESULTS

Fifty-one samples were identified from 42 patients, including 14 aspirates, 7 biopsies and 30 parotidectomies. Previous history was available in 17 cases, 13 parotidectomies accompanied excision of the primary, and relevant clinical data was unavailable for 12 patients. Majority (81%) had head and neck primaries; eye and ocular adnexa were the commonest subsite (52.4%), and sebaceous carcinoma the commonest histology (33%). When history was unavailable, most metastases were initially diagnosed as poorly differentiated carcinoma/malignant tumor, or mucoepidermoid carcinoma on cytology.

CONCLUSIONS

Intraparotid metastases encompass a wide spectrum, often mimicking primary salivary gland neoplasms, particularly on limited samples. Metastases should be considered when histological/cytological features are unusual; detailed clinical information and ancillary techniques aid in arriving at an accurate diagnosis.

Management of the parotid for high-risk cutaneous squamous cell carcinoma: A review from the salivary section of the American Head and Neck Society

BACKGROUND

Metastases to the parotid nodal basin in patients with high-risk cutaneous squamous cell carcinoma (HRcSCC) impact disease specific survival (DSS) and overall survival (OS).

METHODS

A writing group convened by the Salivary Section of the American Head and Neck Society (AHNS) developed contemporary, evidence-based recommendations regarding management of the parotid nodal basin in HRcSCC based on available literature, expert consultation, and collective experience. The statements and recommendations were then submitted and approved by the AHNS Salivary Committee.

RESULTS

These recommendations were developed given the wide variation of practitioners who treat HRcSCC in order to streamline management of the parotid nodal basin including indications for imaging, surgery, radiation, and systemic treatment options as well.

CONCLUSIONS

This clinical update represents contemporary optimal management of the parotid nodal basin in HRcSCC and is endorsed by the Salivary Section of the AHNS.

MR Imaging of Salivary Gland Tumors

Neoplasms of the salivary glands are characterized by their marked histologic diversity giving them nonspecific imaging findings. MR imaging is the best imaging modality to evaluate salivary gland tumors. Multiparametric MR imaging combines conventional imaging features, diffusion-weighted imaging, and perfusion imaging to help distinguish benign and low-grade neoplasms from malignant tumors; however, a biopsy is often needed to establish a definitive histopathologic diagnosis. An awareness of potential imaging pitfalls is important to prevent mistakes in salivary neoplasm imaging.

Intra-parotid lymph node metastasis in patients with non-cutaneous head and neck cancers: clinical and imaging features for differentiation from simultaneous parotid primary tumor

BACKGROUND

Although uncommon, intra-parotid lymph node (IPLN) metastasis should be considered in the differential diagnosis of parotid masses in patients with head and neck cancers.

PURPOSE

To compare the clinical and imaging features of IPLN metastases from head and neck cancers and simultaneous parotid primary tumors.

MATERIAL AND METHODS

A retrospective review of 2199 patients with non-parotid head and neck cancers revealed 63 patients who also underwent parotidectomy during curative resection of head and neck cancer. After exclusion of direct extension to the parotid gland from adjacent primary tumors (n = 12) and IPLN metastases from skin cancer (n = 5), the final study group was composed of 46 patients, including 26 (1.2%) with 33 IPLN metastases and 20 (0.9%) with 24 simultaneous parotid primary tumors. We compared clinical features of patients (sex, age, site of primary tumor, histologic type, history of prior treatment for malignancy, TNM stages, side of parotid lesion, multiplicity, and metastasis in ipsilateral cervical LNs) and the CT (location in parotid gland, maximum dimension, margins, and central necrosis or cystic change) and 18F-FDG PET/CT (maximum standardized uptake value) findings.

RESULTS

Ipsilateral level II LN metastasis was more frequent in the IPLN metastasis group than in the simultaneous parotid primary tumor group (73.1% vs. 35.0%, P < 0.05). Imaging features such as location in parotid gland, maximum dimension, margins, central necrosis or cystic change, and maximum standardized uptake value showed no significant differences between the two groups.

CONCLUSION

CT and PET/CT findings of IPLN metastasis are indistinguishable from simultaneous parotid primary tumor in patients with head and neck cancers.

Multiparametric magnetic resonance imaging of parotid tumors: A systematic review

PURPOSE

The purpose of this systematic review was to provide an overview of the contribution of multiparametric magnetic resonance imaging (MRI) in the diagnosis of parotid tumors (PT) and recommendations based on current evidences.

MATERIAL AND METHODS

We performed a retrospective systematic search of PubMed, EMBASE, and Cochrane Library databases from inception to January 2020, using the keywords "magnetic resonance imaging" and "salivary gland neoplasms".

RESULTS

The initial search returned 2345 references and 90 were deemed relevant for this study. A total of 54 studies (60%) reported the use of diffusion-weighted imaging (DWI) and 28 studies (31%) the use of dynamic contrast-enhanced (DCE) imaging. Specific morphologic signs of frequent benign PT and suggestive signs of malignancy on conventional sequences were reported in 37 studies (41%). DWI showed significant differences in apparent diffusion coefficient (ADC) values between benign and malignant PT, and especially between pleomorphic adenomas and malignant PT, with cut-off ADC values between 1.267×10^-3mm²/s and 1.60×10^-3mm²/s. Perfusion curves obtained with DCE imaging allowed differentiating among pleomorphic adenomas, Warthin's tumors, malignant PT and cystic lesions. The combination of morphological MRI sequences, DCE imaging and DWI helped increase the diagnostic accuracy of MRI.

CONCLUSION

Multiparametric MRI, including morphological MRI sequences, DWI and DCE imaging, is the imaging modality of choice for the characterization of focal PT and provides features that are highly suggestive of a specific diagnosis.

Normative measurements of parotid lymph nodes on CT imaging

PURPOSE

The goal of this study is to characterize the normal size of parotid lymph nodes among healthy adult patients on CT.

METHODS

This was a single-center retrospective observational study of 543 patients who underwent maxillofacial CT scans between January 2019 and July 2019. The long and short axis diameters of the largest lymph nodes in the bilateral superficial parotid glands were measured.

RESULTS

Among the 543 patients, 407 subjects with a mean age of 47.0 ± 18.4 years had a total of 719 detectable intraparotid lymph nodes. The mean patient age was 47.0 ± 18.4 years. Of all 719 measured intraparotid lymph nodes, the measured long and short axis diameter means were 4.4 ± 1.4 mm and 3.3 ± 1.1 mm, respectively. In our study, 96% (689/719) of all lymph nodes had a long axis diameter of 7 mm or less and 93% (671/719) of all lymph nodes had a short axis diameter of 5 mm or less. Younger patients had significantly larger lymph nodes than older patients in both long axis (4.5 vs 4.3 mm; P = 0.03) and short axis (3.4 vs 3.1 mm, P = 0.01) measurements.

CONCLUSION

Our findings suggest 5 mm as an upper limit of normal for the short axis diameter of superficial intraparotid lymph nodes.

Thyroid carcinoma metastasizing to the submandibular gland: Sonographic findings

Metastases to the submandibular gland are extremely rare; a literature search retuned only three previously reported cases from a thyroid gland primary site. Herein, we report two cases of metastatic thyroid carcinoma to the submandibular gland in a 64-year-old woman with PTC and a 70-year-old-woman with medullary thyroid carcinoma (MTC). The metastases were identified on CT and PET/CT in one case and on CT in the other case, but both were diagnosed with ultrasound-guided fine-needle aspiration. Our cases highlight that while rare, both PTC and MTC can metastasize to the submandibular gland.

The key radiologic and cytomorphologic features of oncocytic and oncocytoid lesions of the salivary gland

Oncocytic and oncocytoid lesions represent a distinct subset of salivary gland lesions. True oncocytic lesions of the salivary gland are entirely composed of oncocytes. These are characterized by the presence of abundant eosinophilic granules due to the presence of abundant cytoplasmic mitochondria. Oncocytic lesions of the salivary gland include oncocytosis, oncocytoma, and oncocytic carcinoma. In addition to the true oncocytic lesion, there exists another group of salivary gland lesions, which demonstrate cells with abundant and occasionally granular cytoplasm. These are often termed as "oncocytoid" lesions. The recently proposed Milan System for reporting salivary gland cytology clearly states that fine-needle aspiration specimens representing oncocytic/oncocytoid lesions of salivary gland cannot effectively distinguish between a nonneoplastic lesion, benign and malignant neoplasms. Therefore, most lesions lacking classic cytomorphologic features will be classified under the umbrella diagnostic term of "Salivary Gland Neoplasm of Uncertain Malignant Potential" (SUMP). In this review, we discuss and illustrate key clinicopathologic and radiologic features that can help the practicing cytopathologist narrow down the differential and provide the best management based diagnosis.

Review of the Major and Minor Salivary Glands, Part 2: Neoplasms and Tumor-like Lesions

The salivary glands are small structures in the head and neck, but can give rise to a wide variety of benign and malignant pathology. When this occurs, patients may present with palpable swelling, although it is quite common that they are asymptomatic and a salivary gland mass was discovered as an incidental finding on imaging performed for another reason. It is, therefore, critical that radiologists pay careful attention to the salivary glands and have working knowledge of the key differentiating features of the most common neoplastic and nonneoplastic etiologies of salivary gland masses. The purpose of this review is to provide a succinct image-rich article illustrating the various causes of salivary gland masses via an extensive review of the primary literature. In Part 2, we discuss neoplasms and tumor-like lesions of the salivary glands with a key emphasis on specific imaging features of the most common pathologic entities.

Coincidence of Malignant Melanoma and an Incidently Discovered Parotid Mass Presenting a Diagnostic Challenge

Parotid masses coincided with skin tumors in head and neck region may represent a serious diagnostic challenge. Conventional imaging modalities such as computed tomography, magnetic resonance imaging may help to determine nature of the masses. Positron emission tomography - computed tomography imaging is reported to be useful for the detection of malignancy in the parotid gland. But in some situations all of them become insufficient. We present a case of cheek malignant melanoma with an incidentally discovered parotid mass during the investigation. We describe the problems experienced in the course of differential diagnosis and decision making in terms of surgical management. As a result, the most reliable diagnosis of suspicious parotid lesions accompanying head and neck melanomas comes from frozen section analyses. The other diagnostic tools are not reliable enough to allow a safe surgical plan in terms of regional treatment; however, the significance of positron emission tomography - computed tomography in distant metastasis investigation should always be kept in mind.

Tuberculosis of the parotid lymph nodes: clinical and imaging features

Objectives

To characterize clinical, computed tomography (CT) and magnetic resonance imaging (MRI) features of tuberculosis (TB) of the parotid nodes.

Materials and methods

CT (n=21) and MR (n=7) images, and clinical data from 25 patients with TB of the parotid nodes were retrospectively analyzed by two experienced radiologists who reached consensus.

Results

Younger patients (aged <50 years) accounted for 72%. Eighty percent of patients were asymptomatic, and had no history of TB exposure. According to clinical and imaging findings, 64% and 60% patients were misdiagnosed as having tumors, respectively. A total of 43 lesions were identified. Thirty-eight (88.4%) lesions involved the superficial lobe. Fourteen (56%) cases had multiple lesions. There were four types of changes in the parotid fascia: local thickening (40%, n=10); local rupture with thickened adjacent skin (28%, n=7); focal bulge (20%, n=5); and no changes (12%, n=3). Cervical lymphadenopathy was seen in 14 out of 25 cases (56%). The lesions were contrast-enhanced in four patterns on CT images: homogeneous enhancement (37.1%, n=13), irregular cyst-like enhancement (37.1%, n=13), thick-walled ring enhancement (14.2%, n=5), and garland-like enhancement (11.4%, n=4). On MRI, the signal intensity of lesions was isointense on T1-weighted image, hyperintense on T2-weighted image, markedly hyperintense on diffusion-weighted imaging, and low on the apparent diffusion coefficient map. The surrounding parotid parenchymal edema was identified clearly on coronal MR images.

Conclusion

TB of the parotid nodes tend to simulate tumors clinically and radiologically. Their preferential sites are the superficial lobe. In young patients with positive purified protein derivative skin test and lesions accompanied by cervical lymphadenopathy, changes in the parotid fascia and parotid parenchymal edema adjacent to the lesions on CT and MRI may be helpful in the diagnosis and to facilitate differential diagnosis.

Lymphoepithelial carcinoma of salivary glands: CT and MR imaging findings

OBJECTIVES

To depict the CT and MRI characteristics of salivary gland lymphoepithelial carcinoma (LEC) and provide more diagnostic information for this malignancy.

METHODS

103 salivary gland LEC subjects were retrospectively reviewed. The subjects include 35 males with a mean age of 40.8 years and 68 females with a mean age of 49.4 years. Of the 103 subjects, 86 had carcinomas in the parotid gland, 5 in the submandibular gland, 1 in the sublingual gland, 3 in the cheek and 8 in the palate. All subjects underwent routine CT and MRI (plain and contrast-enhanced scans) prior to surgical treatment and histopathological examination.

RESULTS

Based on the pathological outcomes, all the salivary gland LECs were classified into two types from CT and MRI scans: solitary LEC (56 cases, 54.4%) and multiple LEC (47 cases, 45.6%). The latter included solitary salivary gland LEC with extraglandular lymph-node metastases (12 cases), parotid gland LEC with ipsilateral intraglandular lymph-node metastases (11 cases), parotid gland LEC with ipsilateral intra- and extraglandular lymph-node metastases (23 cases) and bilateral parotid gland LEC (1 case). The salivary gland LEC was depicted on CT and MRI scans as a lobular mass in 64 of 104 (61.5%), homogeneous mass in 65 of 104 (62.5%) or enhanced neoplasm in 94 of 104 (90.4%).

CONCLUSIONS

Salivary gland LEC has a predilection for females in the fourth to fifth decade of life and the parotid gland. CT and MRI findings between solitary and multiple salivary LECs vary. A majority of multiple parotid gland LECs are characterized by metastasis of ipsilateral intraglandular lymph nodes, which may accompany with or without extraglandular lymph-node metastases.