Computed tomography and magnetic resonance imaging of adenoid cystic carcinoma in the maxillary sinus: a retrospective study with radiologic-histopathologic correlations

Primary and Recurrent Intraosseous Adenoid Cystic Carcinoma-Analysis of Two Cases and Literature Review

Adenoid cystic carcinoma (ACC) is a rare malignant tumor that mostly occurs in minor glands, especially in the palate. Intraosseous adenoid cystic carcinoma (IACC) is rarer. There is no clear conclusion on the clinical, radiologic and pathological characteristics of IACC because of few reported IACC cases, leading to insufficient understanding of IACC. We reviewed 52 previous reports of primary IACC (PIACC) and analyzed the clinical features of those patients involved, attempting to provide a better understanding of PIACC. Moreover, we present a case of primary PIACC and a case of recurrent IACC (RIACC). The two patients showed similarities in clinical and pathological results, along with slight differences in radiological and immunohistochemical results. The patient of case 1 seemed to display a worse prognosis, which can only be proved after long term follow-up.

Adenoid cystic carcinoma of head and neck: Summary and review of imaging findings

Purpose

Current reports of adenoid cystic carcinoma of the head and neck (ACC) are all case reports, and there is no basilar summary of its imaging findings. This study aims to summarise ACC's computed tomography (CT) and magnetic resonance imaging (MRI) findings to improve radiologists' knowledge of this disease.

Methods

We collected clinical and imaging data of patients with ACC during the last decade, and two radiologists retrospectively analysed the imaging characteristics.

Results

Of the 16 patients included, six were able to self-perceive bulkiness, and 11 had regional pain. Tumour morphology was regular in six cases, with clear borders in 11 cases, invasion of the surrounding bony mass in 12 cases, and invasion of peripheral nerves in 15 cases. CT mostly shows an irregular soft-tissue density mass with mild-to-moderate enhancement after contrast medium administration. On MRI, the ACC showed isointense or hypointense signals on T1-weighted images (T1WI) and hyperintense or slightly hyperintense signals on T2-weighted images (T2WI). All signals were markedly enhanced after gadolinium enhancement.

Conclusions

ACC often has an irregular morphology, sometimes with a cystic component, enhancement on enhancement scans, easy destruction of adjacent bone, and invasion of peripheral nerves. The diagnosis should be considered when these features are encountered in clinical practice.

Computed Tomography and Magnetic Resonance Imaging Findings Contribute to Differentiating Solid- and Nonsolid-Type Adenoid Cystic Carcinoma in Maxillary Sinus

PURPOSE

This study aimed to evaluate the imaging features of maxillary sinus adenoid cystic carcinoma (ACC) on computed tomography (CT) and magnetic resonance imaging (MRI) and to investigate the imaging differences between solid and nonsolid maxillary sinus ACC.

METHODS

We retrospectively reviewed 40 cases of histopathologically confirmed ACC of the maxillary sinus. All the patients underwent CT and MRI. Based on the histopathological characteristics, the patients were classified into 2 groups: ( a ) solid maxillary sinus ACC (n = 16) and ( b ) nonsolid maxillary sinus ACC (n = 24). Imaging features such as tumor size, morphology, internal structure, margin, type of bone destruction, signal intensity, enhancement changes, and perineural tumor spread on CT and MRI, were evaluated. The apparent diffusion coefficient (ADC) was measured. Comparisons of imaging features and ADC values were performed between the solid and nonsolid maxillary sinus ACC using χ 2 and nonparametric tests.

RESULTS

The internal structure, margin, type of bone destruction, and degree of enhancement significantly differed between solid and nonsolid maxillary sinus ACC (all P < 0.05). The ADC of the solid maxillary sinus ACC was considerably lower than that of the nonsolid maxillary sinus ( P < 0.05).

CONCLUSIONS

Computed tomography and MRI may aid in the differentiation of solid and nonsolid types of maxillary sinus ACC.

FAP-Specific Signalling Is an Independent Diagnostic Approach in ACC and Not a Surrogate Marker of MRI Sequences

Background: Fibroblast Activation Protein (FAP) is a new target for positron emission tomography and computed tomography (PET/CT) imaging of epithelial tumours embedded in a fibrous stroma. Adenoid cystic carcinomas (ACCs) have shown elevated tracer uptake in 68Gallium (68Ga)-labelled FAPIs in previous studies. The current gold standard for ACC imaging is contrast-enhanced (ce) MRI, where intertumoural heterogeneity leads to variable appearance on T1-weighted (T1w) and T2-weighted (T2w) images. In this retrospective analysis, we correlated 68Ga-FAPI PET signalling at three time points with ceT1w and T2w MRI signals to further characterise the significance of 68Ga-FAPI uptake in ACCs. Methods: Clinical PET/CT scans of 12 ACC patients were performed at 10, 60 and 180 min post i.v. administration of 68Ga-labelled-FAPI tracer molecules. 68Ga-PET- and corresponding MRI-scans were co-registered, and 3D volumetric segmentations were performed on ceT1w and T2w lesions of co-registered MRI slides. Signal intensity values of 68Ga-FAPI PET signalling and ceT1w/T2w MRI scans were analysed for their pixelwise correlation in each patient. Pooled estimates of the correlation coefficients were calculated using the Fisher z-transformation. Results: 68Ga-FAPI PET signals showed a very weak positive correlation with ceT1w values (pooled correlation 0.114, 0.147 and 0.162 at 10, 60 and 180 min) and a weak negative correlation with T2w values (pooled correlation −0.148, −0.121 and −0.225 at 10, 60 and 180 min). Individual r-values at 60 min ranged from −0.130 to 0.434 in ceT1w and from −0.466 to 0.637 in T2w MRI scans. Conclusion: There are only slight correlations between the intensity of 68Ga-FAPI PET signals and tumour appearance in ceT1w or T2w MRI scans, which underlines that 68Ga-FAPI PET signalling is not a surrogate marker of MRI sequences but an independent signal.

Current opinions on diagnosis and treatment of adenoid cystic carcinoma

Adenoid cystic carcinoma (ACC) is a rare malignant tumor derived mainly from the salivary glands, representing approximately 1% of all headandneck carcinomasand 10% of all salivary gland neoplasms. ACC displays a paradoxical behavioral combination of an indolent growth pattern but an aggressive progression, with local recurrence and distant metastasis. The propensity of ACC of the head and neck (ACCHN) for perineural invasion and its anatomical location, especially if it extends to the nasal cavity and paranasal sinuses, facilitates tumor involvement in the surrounding structures, such as the orbit, pterygopalatine fossa, Meckel'scave, and cavernous sinus, which can lead to skull base involvement and intracranial extension. Despite advances in molecular mechanisms and diagnostic imaging, ACC treatment remainschallenging due to the lack ofconsensuson treatment patterns. In this review, we aimed toprovideanupdatedinsight intothe understanding of ACCHN by focusing on clinical behavior, imaging diagnosis, pathological features, and therapeutic strategies. We reviewed the molecular mechanisms, especially in ACCHN with perineural invasion, and elaborated on treatment options, including chemotherapy, targeted therapies, and immunotherapy, to establish a comprehensive understanding of ACC to arrive at a policy for proper diagnosis, preoperative evaluation, and therapeutic strategies.

Adenoid cystic carcinoma of sinonasal origin masquerading as an intraconal lesion

Adenoid cystic carcinoma is an uncommon tumour of the salivary glands, although affliction of mucin-producing glands present in the oral cavity, oropharynx and paranasal sinuses is not uncommon. Other possible sites are lacrimal, oesophagus, trachea-bronchial tree, lungs, uterus, cervix, prostate. These tumours have a tendency to be aggressive and most show invasion into the adjacent region. Adenoid cystic carcinoma contributes to about 0.3% of all sinonasal tumours.